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FUEL SYSTEMS

1. AND THROTTLE BODY 5C 157 Intake Manifold and Fuel Rail p i x 4 t SO pe i SQ 72799 Index 5C 158 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Intake Manifold Bolt Washer Bolt Retainer Fuel Rail Bolt Filter O Ring 10 Pressure Regulator VST Models Or Fuel Damper Cool Fuel Models 11 O Ring 12 Screw 13 Nut 14 Schrader Valve 15 Engine Coolant Temperature ECT Sensor 16 Plug 17 Bolt 18 Thermostat Housing 19 Plug 20 Water Temperature Sender 21 Gasket 22 Ihermostat 23 Sleeve 24 Gasket 25 Bolt 26 Washer 2 Bolt 28 Washer 29 Fuel Injector 30 O Ring 31 Grommet 32 Grommet 33 Fitting OONOORWND Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT Fuel Pressure Relief Procedure NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding Disconnect electrical connector at fuel pump 2 Crank engine for ten seconds if engine starts al low it run until it dies to relieve any fuel pressure in the system Multi Port Components Flame Arrestor NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL Remove four flame arrestor mounting cap nuts and remove flame arrestor from throttle body 72790 a Flame Arrestor b Cap Nuts 4 CLEANING AND INSPECTION
2. 5C 186 THIS PAGE IS INTENTIONALLY BLANK Index 90 823224 2 796 weindex info General Information A CAUTION To reduce the chance of personal injury and or property damage the following instructions must be carefully observed proper service and repair are important to the safety of the service technician and the safe reliable operation of all MerCruiser Electronic Fuel Injection Multi Port And Throttle Body equipped engines If part re placement is necessary the part must be re placed with one of the same part number or with an equivalent part Do not use a replacement part of lesser quality The service procedures recom mended and described in this service manual are effective methods of performing service and re pair Some of these procedures require the use of tools specially designed for the purpose Ac cordingly anyone who intends to use a replace ment part service procedure or tool which is not recommended by the system manufacturer must first determine that neither his safety nor the safe operation of the engine will be jeopar dized by the replacement part service procedure or tool selected It is important to note that this manual contains various Cautions and Notes that must be carefully observed in order to reduce the risk of personal injury during ser vice or repair or the possibility that improper ser vice or repair may damage the engine or render it unsafe It is also im
3. 72793 hrottle Body Throttle Position TP Sensor dle Air Control IAC Valve Sight Tube QOO 9 8 Apply Loctite 242 to threads of studs Using a stud driver torque studs to 165 Ib in 18 6 N m a Throttle Body b Throttle Body Mounting Studs SAND THROTTLE BODY 5C 161 NOTE If Boat is equipped with Quicksilver Zero Ef fort Controls the throttle cable mounting stud must be most forward position on throttle lever a Position For Zero Effort Controls 9 Connectthrottle linkage Secure cable barrel an chor stud with locknut and tighten securely Se cure cable end guide to lever stud Thread lock nut on stud until it contacts end guide mhs lt S LC 1 LJ ANN e BONN Mu 1 72791 a Cable Barrel Anchor Stud b Locknut Index 5C 162 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 10 Install flame arrestor to throttle body Apply Loc tite 242 to threads of studs Install four flame ar restor mounting cap nuts Torque cap nuts to 50 Ib in 6 N m oui 72790 a Flame Arrestor b Cap Nuts 4 Plenum NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Remove flame arrestor and throttle body as out lined previously 2 Disconnect IAT and MAP sensor electrical con nectors 7 3 fic _ N _ A RETE s W mul ER STIN ATP 72795 a Intake
4. 72800 Throttle Body Throttle Position TP Sensor Screws With Lockwashers O Ring Install throttle body throttle cable and flame ar restor as outlined in Throttle Body When negative battery cable has been recon nected start engine and check for TP sensor out put voltage It should be approximately 7 V atidle and 4 5 V at W O T 90 823224 2 796 Intake Air Temperature IAT Sensor CLEANING AND INSPECTION NOTICE 1 Clean the surfaces of the IAT with a dry cloth Refer to Service Precautions in Repair 2 Inspect the IAT for signs of wear or damage Procedures BEFORE proceeding INSTALLATION REMOVAL 1 mE IAT in plenum Tighten 2 1 2 turns maxi 1 Remove flame arrestor throttle linkage throttle body and plenum as outlined in Plenum 2 Remove IAT from plenum 72802 72802 a Plenum b Intake Air Temperature IAT Sensor Sos BISHER 2 Install plenum throttle body throttle cable and b Intake Air Temperature IAT Sensor flame arrestor as outlined in Plenum 3 Connect electrical connector to IAT Index mr 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT Sect AND THROTTLE BODY 5C 179 Idle Air Control IAC Valve NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Remove flame arrestor throttle cable and throttle body as outlined in Throttle Body 2 Disconnect electrical connector
5. VAPOR SEPARATOR TANK VST 73797 NOTE Later model VST MCM 454 Magnum EFI Serial Number 0F130438 and MCM 502 Magnum EFI Serial Number 0F128962 and higher will be equipped with the fuel line as shown Earlier VSTs will have fuel lines as shown in figure 2 Vapor Separator Tank VST Grommet Hose Fuel Line Return Plug O Ring Fuel Line VST Supply Grommet Bushing 10 Screw 11 O Ring 12 Fuel Line Supply Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT fee ES AND THROTTLE BODY 5C 141 Vapor Separator Tank VST NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Disconnect fuel pump electrical connector 2 Label and then disconnect all fuel lines from cov er of vapor separator tank lg oe W 9 f P ba o ZU VS SN NEN lt N 72804 a VST b Intake Manifold c Screw d Bushing e Grommet 3 Remove screw and VST from intake manifold Index 5C 142 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY INSTALLATION 1 Install VST to intake manifold Apply Loctite 8831 to threads of attaching screw Torque bolt to 105 lb in 12 N m Connect all lines to cover of vapor separator tank Torque fuel line fittings to 23 Ib ft 31 Connect fuel pump electrical connector With engine off cycle ignition switch to on waiting 2 seconds a
6. BEFORE proceeding REMOVAL 1 Disconnect electrical connector at throttle posi tion TP sensor 2 Remove sensor from throttle body 73758 a Throttle Body Throttle Position TP Sensor c Screws CLEANING AND INSPECTION 1 Clean the surfaces of the TP sensor with a dry cloth 2 Inspect the TP sensor for signs of wear or dam age oO AND THROTTLE BODY 5C 173 INSTALLATION IMPORTANT If the TP sensor is to be replaced with a new unit be sure to secure it in place with the new screws which are included in the service package 1 Install TP sensor to throttle body using screws with washers and Loctite 242 applied to threads Torque screws to 20 Ib in 2 N m 73758 Throttle Body Throttle Position TP Sensor Screws With Lockwashers Seal QOO 9 N Connect electrical connector to TP sensor Install throttle body throttle linkage and flame ar restor as outlined in Throttle Body 4 Start engine and check for TP sensor output volt age It should be approximately 7V at idle and 4 5V at W O T Index 5C 174 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Idle Air Control IAC Valve NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Remove flame arrestor throttle cable and throttle body as outlined in Throttle Body 2 Disconnect electrical connector at idle air control IAC
7. O 9 CLEANING AND INSPECTION IMPORTANT DO NOT immerse the fuel meter cover with pressure regulator in cleaner as damage to the regulator diaphragm and gasket could occur 1 Inspect pressure regulator seating area for pit ting nicks burrs or irregularities Use a magnify ing glass if necessary If any of the above is pres ent replace the cover assembly 90 823224 2 796 INSTALLATION 1 Install new pressure regulator seal fuel meter outlet passage gasket and cover gasket Install fuel meter cover assembly Install attaching screws precoated with appropri ate locking compound to threads Short screws are next to injectors Torque screws to 28 Ib in 3 N m Connect electrical connectors to fuel injectors With engine OFF and ignition ON check for leaks around gasket and fuel line couplings 73767 a Fuel Meter Cover b Pressure Regulator Assembly Gaskets Regulator Passages d Screws Fuel Injectors NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL NOTE Use care in removing fuel injectors to prevent damage to the electrical connector and nozzle IMPORTANT The fuel injector is an electrical component DO NOT soak in any liquid cleaner or solvent as damage may result Index 90 823224 2 796 ELECTRONIC FUEL INJECTION 1 Remove flame arrestor and fuel meter cover as outlined in this section 2 Usi
8. TOTACH GRY 121 WHT TO 931 BRN CIRCUIT DESCRIPTION The audio warning buzzer function of the ECM is used to alert the operator of a critical engine function parameter Used in conjunction with the discrete in put circuitry the ECM will supply ignition current to activate the buzzer if a change of state is indicated by any of the discrete inputs When a discrete switch changes state from normally open to closed the ECM interprets that an anomaly is present and will complete the ground to the affected buzzer circuit energizing the buzzer TEST DESCRIPTION Number s below refer to circled number s on the functional check chart 1 This step performs a functional check of the buzzer circuit 2 Thisstep identifies a short to ground in the control circuit 3 This step identifies an open in the control circuit Index 5C 82 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 112 DK GRN COOLANT OVERTEMP TO BUZZER LOW OIL PRESSURE LOW FLUID TO BUZZER 31 TAN TRANS TEMP MIE TO LOW OIL PRESSURE AND GEAR LUBE SWITCHES TRANS TEMP MIE 4 This step identifies if the fault is a short in the har ness or a faulty ECM 5 his step checks for an open in the circuitry from the harness connector to the ignition fuse 6 This step identifies if the open circuit is due to a faulty ECM or warning buzzer circuitry DIAGNOSTIC AIDS An intermittent problem may be caused by
9. VST fault stuck float leaking vapor regulator Electric fuel pump check valve or fuel pressure regulator and or fuel damper leaking CHECK IGNITION SYSTEM FOR Proper ignition timing Ignition wires for cracking hardness and proper connections at both distributor cap and spark plugs Wet plugs cracks wear improper gap burned electrodes or heavy deposits Repair or replace as necessary Distributor cap inside and out for moisture dust cracks burns and arcing to coil mounting screws Worn distributor shaft Bare and shorted wires Pick up coil resistance and connections Try to turn distributor shaft by hand Drive pin may be broken Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULI x ES AND THROTTLE BODY 5C 117 HARD START continued CHECK SENSORS AND CONTROLS FOR Possible open in Engine Coolant Temperature ECT sensor and Manifold Absolute Pressure MAP sensor Ground CKT 814 Also may have set a DTC 14 and or DTC 33 Throttle Position TP sensor ground CKT 813 could have a possible open and set DTC 21 sticking throttle shaft or binding linkage causes a high Throttle Position TP sensor voltage Using a scan tool and or voltmeter TP sensor voltage should read less than 7 volt with throttle closed Proper Idle Air Control IAC operation CHECK ENGINE FOR 1 Restricted exhaust 2 Proper cylinder compression 3 Proper camshaft timing valve train problem Ind
10. Possible Symptoms Index 5C 30 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 ECM Connector and EFI Symptoms Chart J 1 Circuits Normal Voltage hd e egor Trouble UMP ber 9 ren ymptoms LUE DTC s Not Serial ORN No Serial Data Not ie ee Not C Lanyard J1 21 Stop NONE No Start Switch Not E AE E Not c 0c 5 J1 24 IAT 472 5V NOTE 2 23 Poor Fuel Economy Exhaust Sensor Odor Not E C RR Not o PP Lack Of Performance Exhaust m 5 ere 5 Odor Stall Lack Of Power Surge Rough Idle Exhaust Odor No Siar NOTE The Intake Air Temperature IAT Sensor J1 24 is not used on the 7 4L 7 41 Throttle Body Injection system J1 21 is not used on 1997 and newer models See page 5C 29 for NOTES Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION THROTTLE BODY 5C 31 ECM Connector and EFI Symptoms Chart J 2 Circuits Normal Voltage CERE Num b ees Trouble orn ber dd p Codes ymptoms LUE DTC s TED C Ignition Control BLK 0 0 J2 6 Ref 463 RED NOTE 5 NOTE 5 None Poor Performance Low Ignition Control PUR J2 8 Ref 430 WHT 5V 1 6V None No Restart High Fuel Pump Relay Driver J2 9 465 GRN NOTE B None No Start 1 Coolant Over temp ge
11. 942 PNK SWITCH CIRCUIT CONNECTOR NOT PRESENT OPTIONAL ON SOME MULTI PORT MODELS BLK Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL AND THROTTLE BODY 5C 47 THIS PAGE IS INTENTIONALLY BLANK Index 5C 48 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Diagnostic Circuit Check The Diagnostic Circuit Check is an organized ap proach to identifying a problem created by an elec tronic engine control system malfunction It must be the starting point for any driveability complaint diag nosis because it directs the service technician to the next logical step in diagnosing the complaint NOTE A scan tool that displays faulty data should not be used and the problem should be reported to the manufacturer The use of a faulty scan tool can result in misdiagnosis and unnecessary parts re The scan tool data listed in the table may be used for comparison After completing the diagnostic circuit check and finding the on board diagnostics function ing properly and no trouble codes displayed The Typical Data Values are an average of display val ues recorded from normally operating vessels and are intended to represent what a normally functioning system would typically display Only the parameters listed below are used in this manual for diagnosing If a scan reads other parame ters the values are not recommended for use in diag nosing If all values are within the range i
12. An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared Check harness routing for a potential short to ground in CKT 410 See Intermittents in Troubleshooting IMPORTANT If replacing the ECT tighten hand tight plus 2 1 2 turns maximum 90 823224 2 796 Code 14 ECT Circuit Non Scan 2 of 2 1 IGNITION OFF DISCONNECT ECT SENSOR CONNECTOR IGNITION ON CONNECT DVM ACROSS COOLANT SENSOR HARNESS TERMINALS IS VOLTAGE ABOVE 4 VOLTS NO YES e CONNECT POSITIVE DVM LEAD FROM HARNESS 2 TERMINAL B CKT 410 5 VOLT REFERENCE e CONNECT NEGATIVE DVM LEAD TO A GOOD GROUND ON ENGINE INTERMITTENT CONNECTIONS OR FAULTY ECT SENSOR REFER TO DIAGNOSTIC AID CHART FOR SENSOR VALUES IS VOLTAGE ABOVE 4 VOLTS YES OPEN SENSOR GROUND CKT 814 OR e REMOVE DOVM e IGNITION ON e CONNECT A TEST LIGHT TO BA
13. Index 5C 134 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 POOR FUEL ECONOMY continued CHECK SENSORS AND CONTROLS FOR 1 If MAP TP or Coolant Sensor are erratic there will be poor economy CHECK ENGINE FOR 1 Proper cylinder compression 1 Exhaust system restriction 2 Excessive resistance on bottom of boat dirt barnacles etc 3 Proper size and pitch propeller for application Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT AND THROTTLE BODY 5C 135 Fuel Delivery Systems Cool Fuel System Exploded View Index 5C 136 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Screws 4 Nut 2 Bracket Cover Base Reference Line To Plenum Or Flame Arrestor Fitting Tubing Fuel Pressure Regulator Screw 2 10 Washer 2 11 Washer 12 Fuel Return Line Fitting 13 Rubber Bushing 8 14 Filter 15 Outlet Fuel Line To Fuel Rail Or Throttle Body 16 O Ring 17 Fuel Cooler 18 O Ring 19 Drain Plug 20 Elbow Fitting 21 O Rings 4 22 Electric Fuel Pump 23 O Ring 24 Fuel Pump Inlet Fitting 25 Retainer Bracket 26 Nut 2 2 Cover Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT ES AND THROTTLE BODY 5C 137 Vapor Separator Tank VST Exploded View Index 5C 138 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY cO O N C
14. REPAIR WIRE FROM MOD ULE TERMINAL TO B TERMINAL OF BLACK IGNI TION COIL CONNECTOR OR PRIMARY CKT TO IGNI TION SWITCH UNDER 1 VOLT REPAIR OPEN TACH LEAD OR CONNEC TION AND REPEAT TEST 4 UNDER 10 VOLTS C PNK TERMINAL ONLY CHECK FOR OPEN OR GROUND IN CKT FROM C TERMINAL TO IGNITION COIL IF CKT IS OK FAULT IS IGNI TION COIL OR CONNECTION 1 TO 10 VOLTS REPLACE MODULE AND CHECK FOR SPARK FROM COIL AS IN STEP 6 SPARK NO SPARK SYSTEM OK REPLACE IGNITION COIL AND THROTTLE BODY 5C 75 Ignition System Check 2 of 2 CONNECTOR IGN xi ein GRY CONNECTOR IGNITION CONNECTOR ACH TO DISTRIBUTOR O DISTRIBUTOR SYSTEM RELAY To GRY CONNECTOR CONNECTOR oru REC GRY CONNECTOR TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 5 5C 76 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Applying a voltage 1 5 to 8 volts to module ter minal P should turn the module ON and the Tach terminal voltage should drop to about 7 9 volts This test will determine whether the module or coil is faulty or if the pick up coil is not generat ing the proper signal to turn the module ON This test can be performed by using a DC battery with a rating of 1 5 to 8 volts The use of the test light is mainly to allow the P terminal to be probed more easily Some digital multime
15. c Restart engine and check for proper idle op eration 90 823224 2 796 Knock Sensor NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Disconnect electrical connector at knock sensor located just ahead of starter motor E KoU C LZ ac A SS Nae AMA a Knock Sensor 2 Remove knock sensor from engine block CLEANING AND INSPECTION 1 Clean knock sensor with a dry cloth paying spe cial attention to threads on base 2 Inspect surfaces of knock sensor for signs of wear or physical damage Index 90 823224 2 796 ELECTRONIC FUEL INJECTION INSTALLATION IMPORTANT If installing a new knock sensor be sure to replace it with an identical part Knock sensors are very sensitive and designed for each specific application IMPORTANT In the following step it is very im portant that the knock sensor be torqued to the precise specification Incorrect torquing will re sult in unsatisfactory performance DO NOT use sealer on threads 1 Install Knock sensor in engine block Torque to 12 16 Ib ft 16 3 21 7 N m L m EN A ND X f QU Ell cm lt AY Wen e a 72846 a Knock Sensor 2 Connect electrical connector to knock sensor ES AND THROTTLE BODY 5C 181 Knock Sensor KS Module INSTALLATION 1 Mount KS module to electrical bracket NOTI
16. 12 22 PORT FUEL JUMPER 1249 FUEL PUMP RELAY DRIVER 12 28 IAC COIL A HIGH 12 13 IAC COIL A LOW 2 14 IAC COIL B HIGH 12 29 IAC COIL B LOW 41 5 MASTER SLAVE 11 18 SERIAL DATA 21 7 DIAGNOSTIC TEST TERMINAL MALFUNCTION INDICATOR LAMP 90 823224 2 796 Multi Port Injection Wiring Diagram Chart 2 Of 4 ECM ECT a INTAKE AIR TEMPERATURE UE 5 472 31 24 IAT SENSOR SIGNAL IAT SENSOR 813 BLK 813 BLK THROTTLE POSTION SENSOR TP THROTTLE POSITION 417DKBLU 11 10 SENSOR SIGNAL 5 VOLTS 416 131 15 50115 813 BLK 813 BLK SENSOR GROUND 813 BLK PRESSUR MAP SENSOR A 814 BLK 814 BLK SENSOR GROUND ENGINE COOLANT TEMPERATURE ECT SENSOR ENGINE COOLANT TEMPERATURE ECT SENSOR SIGNAL 410 YEL MANIFOLD IC 416 GRY 11 31 5 VOLTS REFERENCE SURE B 432 LT GRN 21 9 MAP SIGNAL Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x E AND THROTTLE BODY 5C 41 Multi Port Injection Wiring Diagram Chart 3 Of 4 4X IC MODULE i 450 BLK WHT 450 BLK WHT 2 WAY COIL JUMPER HARNESS TO IGNITION RELAY 7 902 RED TO IGNITION RELAY TERM 86 2 WAY BLACK CONNECTOR TO BUZZER TAN BLU 121 TAN TO IGN PUR TO AUDIO WARNING BLU TAN SWITCHES TO TACH GRY 121 WHT 112 DK GRN 31 TAN Index 423 WHT 430 PUR WHT 424 TAN BLK 453 BLK
17. 5C 21 Fuel Metering System Components Multi Port Vapor Separator Tank VST The fuel metering system is made up of the following components e Fuel supply components fuel tank mechanical pump lines etc Vapor Separator Tank VST Fuel pump electrical circuit Fuel rail assembly including Fuel injectors Pressure regulator assembly Fuel Metering System Mechanical Fuel Pump Vapor Separator Tank VST Electronic Control Module Network Of Engine Sensors Water Separating Fuel Filter Fuel Pressure Regulator Fuel Rail Assembly Fuel Tank JIa o noOoobtnv Index 5C 22 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY FUEL SUPPLY COMPONENTS Fuel is drawn from the boats fuel supply tank through a water separating fuel filter by a mechanical fuel pump mounted on and driven by a seawater pump and is delivered to the Vapor Separator Tank VST VAPOR SEPARATOR TANK VST An electric fuel pump located in the VST pumps fuel to the fuel rail assembly The pump is designed to provide fuel at a pressure greater than that required by the injectors The pressure regulator part of the fuel rail assembly regulates fuel pressure to the fuel injectors Unused fuel is returned to the VST NOTE MCM 454 Magnum Multi Port with serial number 0F130438 and MCM 502 Magnum Multi Port with serial number 0F128962 and higher will be equipped with fuel lines as shown in figure A Fuel
18. 90 823224 2 796 ELECTRONIC FUEL INJECTION It is extremely important that the correct KS sensor and module be used for the engine application Using an incorrect KS module will result in unrecognized spark knock and engine damage The KS module ter minal B is powered by 12 volts from the ignition switch thru system relay If the 12 volt power source is not present the KS module cannot send an 8 10 volt signal to the ECM and a false constant spark re tard will result A code 43 will be set Terminal E ofthe KS module is the signal line from the knock sensor If this circuit opens or shorts to ground the KS module will never remove the 8 10 volt signal from terminal C to the ECM and no spark retard will occur The ground circuit for the KS module is con nected to terminal D If the ground circuit opens the KS module will not be able to remove the 8 10 volt signal to the ECM and spark knock cannot be con trolled On certain models serial number OF417516 and below the ECM will do a self test when the following conditions are reached e Engine temperature above 150 F 66 C e Engine RPM above 4000 RPM e 5 024 Hg in 80 kPa manifold pressure THROTTLE POSITION TP SENSOR The Throttle Position TP Sensor is a potentiometer connected to the throttle shaft on the throttle body The TP has one end connected to 5 volts from the ECM and the other to ECM ground A third wire is connected to the ECM to measure the vol
19. AN INTERMITTENT FAILURE A DIAGNOSTIC CODE CHART IS NOT USED Consult the Diagnos tic Aids on the same page as the diagnostic code chart Troubleshooting also covers the topic of In termittents A physical inspection of the applicable sub system most often will resolve the problem Reading Codes The provision for communicating with the ECM is the Data Link Connector DLC connector It is part of the EFI engine wiring harness and is a 10 pin connector which is electrically connected to the ECM It is used in the assembly plant to receive information in check ing that the engine is operating properly before it leaves the plant The code s stored in the ECM s memory can be read either through a scan tool a diagnostic scanner that plugs into the DLC connec tor or by counting the number of flashes of the Mal function Indicator Lamp when the diagnostic code tool is installed and SERVICE mode is selected DLC Connector Once the diagnostic code tool has been connected the ignition switch must be moved to the ON position with the engine not running At this point the Mal function Indicator Lamp should flash Code 12 three times consecutively This would be the following flash sequence flash pause flash flash long pause flash pause flash flash long pause flash pause flash flash Code 12 indicates that the ECM s diag nostic system is operating If Code 12 is not indi cated a problem is present within the dia
20. DOES IT REPLACE BUZZER AND RECHECK IF BUZZER STILL DOES NOT SOUND REPAIR OPEN IN AFFECTED CIRCUIT YES CHECK FOR SHORT TO GROUND IN AFFECTED CIR CUIT IF CIRCUIT IS NOT SHORTED RE PLACE FUSE IGNITION OFF RECONNECT HARNESS CONNECTOR DISCONNECT ECM J2 CONNECTOR WITH FUSED JUMPER STILL CONNECTED TO GROUND PROBE ECM HARNESS ON AFFECTED CIRCUITS BUZZER SHOULD SOUND DOES IT YES FAULTY ECM REPAIR REPLACE ECM OPEN WIRE AND RETEST OR FAULTY CONNECTOR IN AFFECTED CIRCUIT Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL Discrete Input Circuit Check Power Reduction Mode Non Scan 1 of 2 TO SYSTEM RELAY TERM 87 TAN TO BUZZER BLU 121 TAN TO IGN PUR TO AUDIO BLU WARNING TAN SWITCHES TO GRY 931 BRN CIRCUIT DESCRIPTION oeveral discrete switch inputs are utilized by the fuel injection system to identify abnormal conditions that may affect engine operation A pull up switch is cur rently used in conjunction with the ECM to detect criti cal conditions to engine operation If a switch changes states from its normal at rest position that is normally open to closed the ECM senses a change in voltage and responds by entering power reduction mode And activating the audio warning system NOTE Power reduction mode is not used 1997 and later models This engine protection feature allows the driver
21. HAS PRESSURE BUT LESS ABOVE 32 PSI 231 kPa THAN 28 PSI 193 kPa 3 e DISCONNECT FUEL RETURN LINE e ATTACH FLEX HOSE TO RETURN LINE INSERT THE OTHER END IN AN APPROVED GASOLINE CONTAINER NOTE FUEL PRES CHECK FOR RESTRICTED SURE WITHIN 2 SECONDS AFTER IGNITION IS TURNED ON FUEL LINES OK REPAIR FUEL LINE AND RECHECK CHECK FOR RESTRICTED FUEL LOCATE AND CORRECT T RETURN LINE FROM FUEL RESTRICTION IN WATER SEP ABOVE 32 PSI 231 kPa 28 32 PSI 193 231 kPa e IGNITION OFF PRESSURE REGULATOR TO ARATING FUEL FILTER POINT WHERE FUEL LINE WAS e BLOCK FUEL RETURN LINE FOLLOWING DISCONNECTED INSTRUCTIONS CYCLE IGNITION ON PRESSURE SHOULD RISE ABOVE 32 PSI 231 kPa PENE REPLACE FOEL PRESSURE REGULATOR ABOVE 32 PSI HAS PRESSURE BUT LESS 231 kPa THAN 28 PSI 193 kPa FAULTY FAULTY PRESSURE REGULATOR FUEL PUMP Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL E AND THROTTLE BODY 5C 69 Throttle Body Injection Fuel System Diagnosis Continued Chart A 7 5 of 6 TO SYSTEM 902 RED 49 _ 339 PNK BLK d FUEL PUMP RELAY FUSE 450 BLK WHT TL 120 GRY FUEL PUMP TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step checks if there is power to the fuel pump relay Bypassing the relay circuit should cause the fuel pump to run This step should identify if the fault is in the relay or in the f
22. OFF DISCONNECT IAT SENSOR IGNITION ON SCAN TOOL SHOULD DISPLAY TEMPERATURE LESS THAN 22 F 30 C DOES IT NO YES CKT 472 SHORTED TO FAULTY IAT Fold CONNECTION GROUND SENSOR IAT SENSOR FAULTY ECM OPEN SENSOR OPEN CKT 472 GROUND CIRCUIT FAULTY CONNECTION FAULTY CONNECTION OR OR FAULTY ECM FAULTY ECM Index 90 823224 2 796 ELECTRONIC FUEL INJECTION zx AND THROTTLE BODY 5C 105 Code 33 Manifold Absolute Pressure MAP Sensor Circuit Scan 1 of 2 MAP SENSOR TII MANIFOLD ABSOLUTE PRESSURE VACUUM TO ECTSENSOR CIRCUIT DESCRIPTION The Manifold Absolute Pressure MAP sensor re sponds to changes in manifold pressure vacuum The ECM receives this information as a signal volt age that will vary from about 1 1 5 volts at closed throttle idle to 4 0 4 8 volts at Wide Open Throttle W O T low vacuum The scan tool displays manifold pressure in kPa of pressure and voltage Low pressure high vacuum reads a low voltage while a high pressure low vacu um reads a high voltage If the MAP sensor fails the ECM will substitute a fixed MAP value and use engine RPM to control fuel deliv ery TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 Engine misfire or a low unstable idle may set Code 33 Disconnect MAP sensor and system will go into backup mode If the misfire or idle condition remains
23. em L L NOTE J2 7 is not used on the 7 4L 7 4LX Throttle Body Injection system Power Reduction Mode or Improp er Audio Warning Index 5C 32 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 ECM Connector and EFI Symptoms Chart J 2 Circuits Circuit Normal Voltage Diag CKT Wire nostic Possible Color Trouble LUE Codes Symptoms LUE DTC s Ce C Cad ___ Fuel I BLK 0 0 Rough Running Poor Idle Lack J2 20 Injector 450 WHT mores ores None Of Performance Ground Injector DK Rough Idle Lack Of Power Ignition 0 Stall Will Restart In Bypass ignal Ignition TAN 0 D 2 24 Control Bypass C C c os N Discrete Switch BLU Not Not GRN Not Not Not NOTE J2 22 is not used on the 7 4L 7 4LX Throttle Body Injection system See page 5C 29 for NOTES Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION ey AND THROTTLE BODY 5C 33 Multi Port Injector Balance Test Refer to the following figure for test set up The injector balance tester is a tool used to turn the injector ON for a precise amount of time thus spray ing a measured amount of fuel into the manifold This causes a drop in fuel rail pressure that we can record and compare between each injector All injectors should have the same amount of pressure drop Any injector with a pressure drop that is 1 5 PSI or more greater or les
24. may occur when installing the gauge DIAGNOSTIC AIDS e Unless engine enters Clear Flood at the first in dication of a flooding condition it can result in a no start e Check for fouled plugs e Water or foreign material in fuel line VST water separating fuel filter can cause a no start in cold weather e Adefective MAP sensor may cause ano start or a Stall after start To determine if the sensor is causing the problem disconnect it The ECM will then use a default value for the sensor and If the condition is corrected and the connections are OK replace the sensor e Using injector harness test light J 34730 2A check for blinking light at injector harness on both banks of the engine If not OK check injector fuses If above are all OK refer to Troubleshooting 90 823224 2 796 Engine Cranks but Will Not Run Continued Chart A 3 2 of 4 Q ENSURE THE ENGINE IS NOT IN SERVICE OR BASE TIMING NOTE 1 IF A SCAN TOOL IS NOT AVAILABLE WHILE MODE CHECK THAT LANYARD STOP SWITCH IS NOT ACTIVATED CHECKING TP AND ECT READINGS USE THE CHECK THE FOLLOWING NOTE 1 CODE 21 AND 14 NON SCAN DIAGNOSTIC e ACTUAL ENGINE TEMPERATURE AND ECT TEMPERATURE CHARTS TO ENSURE PROPER OPERATION ON THE SCAN TOOL SHOULD BE CLOSE TO THE SAME IF NOT REFER TO CODE 14 OF THOSE COMPONENTS e TP SENSOR IF OVER 2 5 VOLTS AT CLOSED THROTTLE USE THE CODE 21 CHART NOTE 2 A TACHOMETER MAY BE USED IF A SCAN TOOL IS RPM INDICAT
25. the transistor turns OFF When the transistor turns ON current flows through the primary winding of the ignition coil When it turns OFF the primary current stops and a spark is developed at the spark plug A small amount of ad vance is built into the IC module via a timing circuit in case the engine remains in the ignition module tim ing mode With the relay de energized a set of contacts shown closed would ground the IC line signal ECM Control Mode When the engine RPM reaches a predetermined val ue for this example 300 RPM the ECM considers the engine running and applies five volts on the by pass line to the IC module This energizes the relay and causes the contacts from the pickup coil as well as the grounding contacts for the IC line to open see figure ECM Control Mode This connects the IC line to the base of the transistor and bypasses the ignition module timing control The IC system is now controlled by the IC signal from the ECM and the time at which the spark occurs can be determined by a variable time circuit in the ECM Base Ignition Timing In order to check or change base timing on a HEI sys tem the ECM has to be entered into the service mode by using ascan tool or code tool The IC module will go to base timing The ECM will stabilize timing to al low timing adjustment The ECM incorporates a spark control override which allows timing to be low ered if spark knock detonation is encountered du
26. 114 Diagnostic Trouble Codes 5C 114 Important Preliminary Checks 5C 114 Troubleshooting Charts 5C 115 Fuel Delivery Systems 5C 136 Cool Fuel System Exploded View 5C 136 Vapor Separator Tank VST Exploded View 5C 138 VST Fuel Pump Exploded View 5C 140 Vapor Separator Tank VST 5C 142 Float and Needle Assembly 5C 143 Diaphragm Assembly 5C 144 Throttle Body Injection Repair Procedures 5C 146 Special Tools 5C 146 Lubricants Sealants Adhesives 5C 146 Torque Specifications 5C 146 Throttle Body Injection System Description 5C 147 Service Precautions 5C 147 Throttle Body Exploded Views 5C 148 Induction System 5C 148 Throttle Body 5C 149 Fuel Pressure Relief Procedure 5C 150 Fuel Meter Cover Assembly 5C 150 Index 90 823224 2 796 weindex info Page Fuel Injectors 5C 151 Throttle Body 5C 152 Throttle Body Adapter Plate 5C 153 Multi Port System Description 5C 154 Service Precautions 5C 154 Multi Port Exploded Views 5C 155 Flame Arrestor and Throttle Body 5C 155 uin 5C 156 Intake Manifold and Fuel Rail 5C 158 Fuel Pressure Reli
27. 2 796 INSTALLATION Knock Sensor KS Module 1 Mount new ECM to electrical bracket NOTICE 2 Connect J1 and J2 electrical connectors to the Refer to Service Precautions in Repair ECM Procedures BEFORE proceeding REMOVAL 1 Remove Knock Sensor from electrical bracket 72801 a Electrical Bracket b ECM c J1 Electrical Connector Front Connector d J2 Electrical Connector Rear Connector a Electrical Bracket b Knock Sensor KS Sensor 2 Disconnect electrical connector at Knock Sensor KS module CLEANING AND INSPECTION 1 Clean the external surfaces of the KS module with a dry cloth 2 Inspect surfaces of KS module for evidence of damage Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 171 INSTALLATION 1 Disconnect electrical connector at Engine Cool 1 Connect electrical connector to the Knock Sen ant Temperature ECT sensor sor KS module 2 Mount KS module to electrical bracket a Thermostat Housing b Engine Coolant Temperature ECT Sensor 2 Remove ECT from thermostat housing CLEANING AND INSPECTION 1 Clean with a dry cloth removing any excess seal ant from the base threads 2 Look for evidence of any physical damage to base or connector surfaces of the ECT INSTALLATION 1 Install ECT in thermostat housing TIGHTEN HAND TIGHT PLUS 2 1 2 TURNS MAXIMUM 72801 a Electrical Bracket
28. 33 MAP Circuit Scan 2 of 2 IF ENGINE IDLE IS ROUGH UNSTABLE OR INCORRECT CORRECT CONDITION BEFORE USING CHART SEE THE TROUBLESHOOTING SECTION ENGINE IDLING DOES SCAN TOOL DISPLAY A MAP SENSOR VOLTAGE OF LESS THAN 1 VOLT OR GREATER THAN 4 VOLTS YES VOLTAGE LESS THAN 1 VOLT IGNITION OFF DISCONNECT MAP SENSOR ELECTRICAL CONNECTOR JUMPER MAP SENSOR HARNESS TERMINALS C AND B TOGETHER START ENGINE DOES SCAN TOOL DISPLAY MAP SENSOR VOLTAGE GREATER THAN 4 VOLTS CODE 33 IS INTERMITTENT IF NOT ADDITIONAL CODES WERE STORED REFER TO DIAGNOSTIC AIDS ON FACING PAGE VOLTAGE GREATER THAN 4 VOLTS IGNITION OFF DISCONNECT MAP SENSOR ELECTRICAL CONNECTOR START ENGINE SCAN TOOL SHOULD DISPLAY A VOLTAGE OF LESS THAN 1 VOLT DOES IT IGNITION OFF e CONNECT DVOM BETWEEN IGNITION ON YES MAP SENSOR HARNESS TERMINAL C AND A IS VOLTAGE OVER 4 VOLTS NO YES CKT 416 OPEN FAULTY ECM CONNECTION OR FAULTY ECM OR AT ECM OR CHECK FOR MAP SENSOR SIGNAL CKT 432 SHORTED TO GROUND IF OK REPLACE MAP SENSOR YES NO IGNITION OFF IGNITION OFF e CONNECT DVM e MAP SENSOR BETWEEN MAP SIGNAL CKT 432 SENSOR HARNESS SHORTED TO TERMINAL A VOLTAGE AND OR IGNITION ON FAULTY ECM e VOLTAGE SHOULD CONNECTIONS OR BE GREATER THAN FAULTY ECM 4 VOLTS IS IT MAP SENSOR SIG
29. AND REPLACE DISTRIBUTOR MODULE 1 OF 2 PAGE 78 VOLTAGE DROPS 6 e CHECK FOR SPARK FROM COIL WIRE WITH TIMING LIGHT AS TEST LIGHT IS REMOVED FROM MODULE TERMINAL NO SPARK e REPLACE IGNITION COIL AND REPEAT STEP 5 NO SPARK IGNITION COIL REMOVED IS OK REINSTALL COIL AND CHECK COIL WIRE FROM DIST CAP IF OK RE PLACE DISTRIBUTOR MODULE naex 90 823224 2 796 NO DROP IN VOLTAGE CHECK MODULE GROUND IF OK REPLACE MODULE e IS ROTATING POLE PIECE STILL MAGNE TIZED SPARK m No REPLACE POLE PIECE AND SHAFT ASSEMBLY CHECK PICK UP COIL OR CONNECTIONS COIL RESISTANCE SHOULD BE 500 1500 OHMS AND NOT GROUNDED ELECTRONIC FUEL INJECTION MUL x AND THROTTLE BODY 5C 77 Idle Air Control IAC Functional Test 1 of 2 441 BLU WHT 442 BLU BLK 443 GRN WHT 444 GRN BLK IDLE AIR CONTROL IAC VALVE CIRCUIT DESCRIPTION The ECM controls idle speed to a calculated de sired RPM based on sensor inputs and actual en gine RPM determined by the time between succes sive ignition reference pulses from the ignition module The ECM uses four circuits to move an Idle Air Control IAC valve which allows varying amounts of air flow into the intake manifold control ling idle speed IMPORTANT Improper IAC readings or improper idle speed can result from other faults ie flood ing VST fouled spark plugs bad sensors These items should be in proper worki
30. AND THROTTLE BODY SENSOR GROUND 813 BLK 417 DK BLU TP SIGNAL 416 GRY 5V REFERENCE DIAGNOSTIC AIDS The scan tool reads throttle position in voltage and percentage of throttle blade opening With ignition ON or at idle TP signal voltage should read between 3 and 8 volt with the throttle closed and increase at a steady rate as throttle is moved toward Wide Open Throttle W O T If Code 23 is also set check CKT 813 for faulty wiring or connections Check terminals at sensor for good contact An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 21 TP Sensor Circuit Scan 2 of 2 Q e THROTTLE CLOSED IGNITION ON DOES SCAN TOOL INDICATE THROTTLE POSITION SENSOR VOLTAGE GREATER THAN 4 VOLTS OR LESS THAN 36 VOLT YES CODE 21 IS INTERMITTENT REFER TO DIAGNOSTIC AIDS ON FACING PAGE VOLTAGE
31. AND THROTTLE BODY 5C 99 Diagnostics Using Scan Tool Scan Code 14 Engine Coolant Temperature ECT Sensor Circuit Scan 1 of 2 i ENGINE COOLANT TEMPERATURE ECT SENSOR 2a TO MAP SENSOR CIRCUIT DESCRIPTION The Engine Coolant Temperature ECT Sensor uses a thermistor to control the signal voltage to the ECM The ECM applies a voltage on CKT 410 to the sensor When the engine coolant is cold the sensor thermistor resistance is high therefore the ECM will see high signal voltage As the engine coolant warms the sensor resistance becomes less and the voltage drops At normal engine operating tempera ture 160 180 F 71 82 C the voltage will measure about 1 5 to 2 0 volts TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 Code 14 will set if e Signal voltage indicates a coolant tempera ture above 266 F 130 C e Signal voltage indicates a coolant tempera ture below 22 F 30 C 2 This test will determine if CKT 410 is shorted to ground which will cause the condition for Code 14 Index 5C 100 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY ENGINE COOLANT TEMPERATURE ECT 410 YEL 5V 814 BLK SENSOR GROUND DIAGNOSTIC AIDS Check harness routing for a potential short to ground in CKT 410 Scan tool displays engine temperature in degrees Fahrenheit and Celsius After engine is started the temperature should
32. Air Temperature IAT Sensor b Manifold Absolute Pressure MAP Sensor 90 823224 2 796 3 Disconnect reference line at pressure regulator E I T gm S d _ ay i Ts eA 72796 a Reference Line b Pressure Regulator 4 Remove twelve plenum mounting fasteners and lift straight up from intake manifold Turn plenum slightly and rest on intake manifold as shown Disconnect drain line at plenum and remove ple num a INS mes Pass II im SS SN N CLR a mir b 72797 a Plenum b Intake Manifold c Drain Line IMPORTANT Place a clean shop towel over each of the eight intake manifold openings to prevent foreign material from entering the engine CLEANING AND INSPECTION IMPORTANT Use care when removing gasket material from intake manifold and plenum Fail ure to do so could result in damage to the intake 2 Clean plenum in solvent and dry with com pressed alr 3 Inspect mating surfaces for damage that could affect gasket sealing 4 Inspect plenum for cracks in casting INSTALLATION 1 Install one gasket onto each of the four intake manifold trumpets 2 Restplenum on intake manifold as shown Con nect drain line at plenum Lower plenum evenly onto intake manifold and install twelve plenum mounting fasteners Torque fasteners to 150 Ib in 17 N m a _ 0 bee M ree S Contin 2 72797 a Ple
33. Clean flame arrestor in solvent and dry with com pressed air INSTALLATION 1 Install flame arrestor to throttle body 2 Apply Loctite 242 to threads of studs Install four flame arrestor mounting cap nuts Torque cap nuts to 50 Ib in 6 N m AND THROTTLE BODY 5C 159 Throttle Body 3 Remove four throttle body mounting studs using a stud driver NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding i a M REMOVAL 1 Remove four flame arrestor mounting cap nuts Ra and remove flame arrestor from throttle body KP a Throttle Body b Throttle Body Mounting Studs os 4 Turn throttle body as shown and disconnect drain oui 72790 tube and IAC electrical connectors a Flame Arrestor b Cap Nuts 4 2 Disconnect throttle linkage cms ad f N a m5 LTE lt El f 3 AL e SCA p ow A D SUL SIS 72793 Throttle Body Throttle Position TP Sensor Idle Air Control IAC Valve M a O OO 9 Drain Tube NAR IMPORTANT To prevent damage to throttle 028 valve it is essential that throttle body be placed on a holding fixture before performing service a Throttle Linkage Connections IMPORTANT Insert a clean shop towel into the opening of the plenum to prevent foreign materi al from entering the engine Index 5C 160 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE B
34. DIST REFERENCE LOW CIRCUIT DESCRIPTION This chart assumes that battery condition and engine cranking speed are OK and there is adequate fuel in the tank TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart All injectors should be within 1 0 ohm of each oth er and should not be less than 12 ohms at 70 F 21 If an injector is suspected for a no start condition unhook the suspected injector and try to start the engine Use fuel pressure gauge 91 16850 or J 34730 1 Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that An ECT sensor that indicates coolant tempera ture less than actual temperature can flood the engine with fuel An ECT sensor that indicates coolant temperature greater than actual can starve the engine of fuel If the TP sensor is at 50 to 75 of its range the engine may be in the clear flood mode which will cause starting problems The engine will not start without reference pulses and therefore the scan tool should read engine reference during cranking No spark may be caused by one of several com ponents related to the high energy ignition IC system The ignition system will address all prob lems related to the causes of a no spark condi tion The test light should blink indicating the ECM is controlling the injectors OK Index 5C 56 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY
35. DOES CODE 42 SET IGNITION OFF DISCONNECT ECM CONNECTORS IGNITION ON USE DVM WITH SELECTOR IN OHMS RANGE PROBE ECM HARNESS CONNECTOR CKT 423 WITH DVM TO GROUND IT SHOULD READ MORE THAN 3000 OHMS DOES IT YES e PROBE ECM HARNESS CONNECTOR CKT 424 WITH A TEST LIGHT TO BATTERY VOLTAGE LIGHT OFF 3 e WITH OHMMETER STILL CONNECTED TO ECM HARNESS CKT 423 AND GROUND AGAIN PROBE ECM HARNESS CKT 424 WITH THE TEST LIGHT CONNECTED TO BATTERY VOLTAGE AS TEST LIGHT CONTACTS CKT 424 RESISTANCE SHOULD SWITCH FROM OVER 3000 TO UNDER 1000 OHMS DOES IT e DISCONNECT DIST 4 WAY CONNECTOR NOTE OHMMETER THAT IS STILL CONNECTED TO CKT 423 AND GROUND RESISTANCE SHOULD HAVE GONE HIGH OPEN CIRCUIT DOES IT YES NO CKT 424 OPEN FAULTY CKT 423 CONNECTIONS OR FAULTY SHORTED TO IGNITION MODULE GROUND Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared CODE 42 INTERMITTENT REFER TO DIAGNOSTIC AIDS ABOVE OPEN CKT 423 FAULTY CONNECTION OR FAULTY IGNITION MODULE LIGHT ON e DIS
36. Data or Will Not Flash Code 12 Chart A 2 2 of 2 e MARINE DIAGNOSTIC CODE TOOL INSTALLED IGNITION ON ENGINE OFF IS THE MALFUNCTION INDICATOR LIGHT ON e ENTER SERVICE MODE ON DIAGNOSTIC CODE TOOL DOES MALFUNCTION INDICATOR LAMP FLASH CODE 12 IGNITION OFF e IF PROBLEM WAS NO DLC DATA USING SCAN TOOL DISCONNECT ECM J 2 CONNECTOR CHECK SERIAL DATA CKT 461 FOR OPENS OR SHORTS IGNITION ON AND NOTE MALFUNCTION INDICATOR TO GROUND IF OK IT IS A FAULTY ECM LAMP LIGHT ON IGNITION OFF REPAIR SHORT TO JUMPER TERMINALS A TO B AT DLC CONNECTOR GROUND IN CKT 419 CONNECT TEST LIGHT BETWEEN ECM CONNECTOR TERMINAL J1 7 AND B BATTERY POSITIVE LIGHT ON LIGHT OFF 4 e REPLACE ECM e CHECK FOR OPEN IN DLC DIAGNOSTIC e RECHECK FOR CODE 12 TERMINALS A AND B CKT 450 AND CKT 451 REPAIR AS NECESSARY Index Bm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x I2 AND THROTTLE BODY 5C 55 Engine Cranks but Will Not Run Chart A 3 1 of 4 INJ ECM KS MODULE FUSE 10A PNK BLK c GBRE P 439 PNK BLK INJECTORS SARALA 481 RED lt a gt 467 DK BLU gla INJECTORS 450 syrmi LTGRN BLKWHT TIME 450 481 RED ITM EY BLK WHT 7 ENGINE B GROUND 423 WHT 430 PPLANHT 424 TAN BLK 453 BLI RED 21 11 IGNITION FEED INJECTOR DRIVER IGNITION CONTROL 22 8 DIST REFERENCE HIGH
37. FOLLOWING ECM CONNECTOR AND SYMPTOM CHARTS The B Symbol indicates a system voltage battery NOTE 1 Battery voltage for first two seconds then 0 volts NOTE 2 Varies with temperature NOTE 3 Varies with manifold vacuum NOTE 4 Varies with throttle movement NOTE 5 Less than 5 volt 500 mV NOTE 6 Dualor multiple engines must share a com mon ground for proper serial data communica tions ey AND THROTTLE BODY 5C 29 ECM Connector and EFI Symptoms Chart J 1 Circuits Circuit Normal Voltage Diag ire Num Color Trouble ber LUE Codes 4 LUE DTC s Knock Poor Fuel Economy Sensor 485 BLK 9 5V 9 5V 43 Poor Performance Signal Detonation Poor Performance J1 2 IER 410 YEL N A 14 Exhaust Odor Rough Idle 9 RPM Reduction Not Not mium fo 1 5 Master 916 VEL B4 B4 None Lack Of Data From Other Engine Slave Dual Engine Only Ji g Discrete BRN None Power Reduction Mode Switch Diag WHT J1 7 nostic 451 BLK B B None Incorrect Idle Poor Performance Test Not refuse fo _ Map LT 1 46V Poor Performance Surge Poor J1 10 TP 417 DK 62V 62V 24 Poor Performance And Accelera Signal BLU NOTE 4 NOTE 4 tion Incorrect Idle Ignition PNK Not fff L J1 13 L 21 23 High Idle Rough Idle Poor Perfor m 5 T 5 mance Exhaust Odor Ground ECM BLK Jri6 Batey 440 e 5 Noe See Page 5C 29 For NOTES
38. IAC valve can be reset by doing the following Turn off engine wait ten se conds and restart engine IAC Valve Air Flow Diagram 454 502 Throttle Body a Air Hole b Air Tube Models With VST 72986 NOTE Not all 454 502 Magnums have the air hole located in the secondary throttle plate 90 823224 2 796 ECM Connector and Symptom Charts The following chart will aid in diagnosis of symptoms These voltages were derived from a known good engine The voltages shown were done with the electrical system intact and operational These are voltage requirements to operate the different circuits CAUTION Do not attempt to obtain these voltages by probing wires and connectors Serious damage could result in loss of engine operation or wiring damage Voltages can vary with battery conditions J 1 J 1 Front Pin 32 Pin Input Connector J 2 Rear 32 Pin Output Connector a Shaded Area Denotes Pin Connector Location Used On Terminal NOTE The Intake Air Temperature IAT Sensor J1 24 Port Fuel Jumper J2 7 and J2 22 is not used on the 7 4L 7 4LX Throttle Body Injection system IMPORTANT The following conditions must be meet before testing 1 Engine at operating temperature 2 Ignition on or engine running 3 Scan tool not connected Index 90 823224 2 796 m3 tim w lt gt rn ro Pd ce d ELECTRONIC FUEL INJECTION THESE NOTES APPLY TO
39. LESS THAN 36 VOLT VOLTAGE GREATER THAN 4 VOLTS e IGNITION OFF 2 e IGNITION OFF e DISCONNECT THROTTLE POSITION SENSOR e DISCONNECT THROTTLE POSITION ELECTRICAL CONNECTOR JUMPER THROTTLE POSITION SENSOR HARNESS TERMINALS AND TOGETHER e IGNITION ON e SCAN TOOL SHOULD INDICATE THROTTLE POSITION SENSOR VOLTAGE GREATER THAN 4 VOLTS DOES IT SENSOR CONNECTOR IGNITION ON DOES SCAN TOOL INDICATE VOLTAGE OVER 4 VOLTS NO YES e IGNITION OFF REPLACE THROTTLE CONNECT DVOM CKT 417 SHORTED e CONNECT DVM BETWEEN POSITION SENSOR BETWEEN THROTTLE POSITION HARNESS THROTTLE POSITION SENSOR CONNECTOR HARNESS TERMINAL A AND GROUND GNITION ON IS VOLTAGE OVER 4 VOLTS FAULTY ECM CONNECTION OR FAULTY ECM TERMINALS C AND A VOLTAGE SHOULD BE GREATER THAN 4 VOLTS IS IT YES CKT 416 OPEN OR THROTTLE POSITION YES NO SENSOR SIGNAL CKT 417 OPEN OR REPLACE THROTTLE OPEN SENSOR GROUND SHORTED TO POSITION SENSOR CKT 813 OR FAULTY ECM CONNECTION OR FAULTY ECM FAULTY ECM CONNECTION OR FAULTY ECM FAULTY CONNECTION AT ECM OR FAULTY ECM Index Bm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT x AND THROTTLE BODY 5C 103 Code 23 Intake Air Temperature IAT Sensor Circuit Scan 1 of 2 INTAKE AIR TEMPERATURE SENSOR CIRCUIT DESCRIPTION The Intake Air Temperature IAT sensor uses a
40. MAP SIGNAL SENSOR GROUND ENGINE COOLANT TEMPERATURE ECT SENSOR SIGNAL Throttle Body Injection Wiring Diagram Chart 3 Of 4 450 BLK WHT IC MODULE R 450 BLK WHT PN O C GBRE Gel UL ABCD 423 WHT 430 PUR WHT 424 TAN BLK 2 WAY COIL JUMPER HARNESS 453 BLIURED 121 BRN 3 PNK IGN COIL PRIMARY TO IGNITION RELAY 902 RED TO IGNITION RELAY TERM 86 2 WAY BLACK CONNECTOR TO BUZZER TAN BLU 121 TAN TO IGN PUR TO AUDIO WARNING BLU TAN SWITCHES TOTACH GRY 121 WHT 112 DK GRN 31 TAN 931 BRN Index 5C 46 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY ECM 11 14 ECM GROUND 1 30 ECM GROUND Emi IGNITION CONTROL DIST REFERENCE HIGH BYPASS DIST REFERENCE LOW COOLANT OVERTEMP TO BUZZER LOW OIL PRESSURE LOW J2 27 FLUID TO BUZZER TO LOW OIL PRESSURE AND J1 6 GEAR LUBE SWITCHES OR TRANS TEMPERATURE 90 823224 2 796 Throttle Body Injection Wiring Diagram Chart 4 Of 4 TO IGN COIL TERM B TO FUEL PUMP RELAY FUSE 15A TO INJECTORS ECM SYSTEM IGNITION RELAY TOB 439 PNK BLK 11 11 IGNITION FEED 2RED ECM BAT FUSE 10A 440 ORN 71 32 BATTERY FEED 440 ORN 21 16 BATTERY FEED TO DLC CONNECTOR 4 440 439 PNK BLK KNOCK KNOCK SENSOR KS 485 BLK 31 1 SENSOR KS MODULE 486 BRN 1 496 DK BLU SENSOR TE L Z LANYARD STOP
41. RED 121 BRN 3 PNK IGN COIL PRIMARY 931 BRN 5C 42 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY ECM 11 14 ECM GROUND 1 30 ECM GROUND rz 2 27 1 6 IGNITION CONTROL DIST REFERENCE HIGH BYPASS DIST REFERENCE LOW COOLANT OVERTEMP TO BUZZER LOW OIL PRESSURE LOW FLUID TO BUZZER TO LOW OIL PRESSURE AND GEAR LUBE SWITCHES OR TRANS TEMPERATURE 90 823224 2 796 Multi Port Injection Wiring Diagram Chart 4 Of 4 TO IGN COIL TERM B TO FUEL PUMP RELAY FUSE 15A TO INJECTORS ECM 150 BLK 1 TOB 30 902 RED INJ ECM FUSE 2RED ECM BAT FUSE 10A DLC 15A SYSTEM IGNITION RELAY 439 PNK BLK 11 11 IGNITION FEED 440 ORN 11 32 121 16 BATTERY FEED 440 ORN TO DLC CONNECTOR 4 amp 440 439 PNK BLK Aie KNOCK sO SENSOR KS MODULE 486 BRN 496 DK BLU SENSOR T LET FEE LT V LANYARD STOP 942 PNK SWITCH CIRCUIT CONNECTOR NOT PRESENT ON SOME MULTI PORT MODELS n BLK OPTIONAL Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x E AND THROTTLE BODY 5C 43 Throttle Body Injection Wiring Diagram Chart 1 of 4 INJECTOR asi CCAS YT YY VB 481 467 DK BLU 22 21 INJECTOR DRIVER ENGINE 450 BLI WHT 12 15 INJECTOR GROUND 439 PNK ciouna 4 FUSE zt 450 BLKANHT INJECTOR GROUND 10A INJECTOR 22 20
42. The MAP sensor is also used to mea sure barometric pressure under certain conditions which allows the ECM to automatically adjust for dif ferent altitudes The ECM sends a 5 volt reference signal to the MAP sensor As the manifold pressure changes the elec trical resistance of the MAP sensor also changes By monitoring the sensor output voltage the ECM knows the manifold pressure A higher pressure low vacuum high voltage requires more fuel while a lower pressure higher vacuum low voltage re quires less fuel The ECM uses the MAP sensor to control fuel delivery and ignition timing A failure in the MAP sensor circuit should set a Code 33 90 823224 2 796 KNOCK SENSOR The knock sensor is mounted on the lower right side of the engine block 73051 When abnormal engine vibrations spark knock are present the sensor produces a voltage signal which is sent to the KS Module and then to the ECM The ECM uses this signal to aid in calculating ignition tim ing KNOCK SENSOR KS MODULE The KS module contains solid state circuitry which monitors the knock sensor s AC voltage signal and then supplies an 8 10 volt signal if no spark knock is present to the ECM If spark knock is present the KS module will remove the 8 10 volt signal to the ECM Knock Sensor System Electronic Control Module ECM 12 Volts Battery Positive 8 12 Volts Knock Sensor Knock Sensor Module O O O 9 Index
43. a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness 90 823224 2 796 Audio Warning Buzzer Circuit Check 2 of 2 Q IGNITION ON BUZZER SHOULD SOUND AND THEN SILENCE WITHIN 2 SECONDS DOES IT D BUZZER REMAINS ON CONSTANTLY WITH IGNITION ON DISCONNECT HARNESS CONNECTOR TO BUZZER BUZZER SHOULD SILENCE DOES IT YES e RECONNECT HARNESS CONNECTOR IGNITION OFF DISCONNECT ECM J2 CONNECTOR IGNITION ON BUZZER SHOULD BE SILENT IS IT REPAIR SHORT TO GROUND BETWEEN HARNESS CONNECTOR AND J2 CONNECTOR REPAIR SHORT TO GROUND IN AFFECTED CIRCUIT BETWEEN BUZZER AND CONNECTOR YES FAULTY ECM REPLACE ECM AND RETEST BUZZER CIR CUIT YES NO PROBLEM FOUND RE FER TO DIAGNOSTIC AIDS ON FACING PAGE G e BUZZER NEVER SOUNDS CHECK CIRCUIT BREAKER IN STARTING CHARGING SYS TEM DISCONNECT HARNESS CONNECTOR USING FUSED JUMPER CONNECTED TO GROUND PROBE CONNECTOR BUZZER SIDE OF AFFECTED CIRCUIT BUZZER SHOULD SOUND
44. an open ignition coil primary winding a small amount of voltage will leak through the module from the Battery Positive B to the Tach terminal 90 823224 2 796 Ignition System Check 1 of 2 e DISCONNECT TACH BEFORE PROCEEDING WITH THE TEST e CHECK SPARK AT PLUG WIRE USING AN INDUCTIVE PICKUP TIMING LIGHT WHILE CRANKING A FLASHING LIGHT INDICATES SPARK IF NO SPARK ON FIRST WIRE CHECK SECOND WIRE A FEW SPARKS AND THEN NOTHING IS CONSIDERED NO SPARK NO SPARK e DISCONNECT 4 TERMINAL CONNECTOR ON DISTRIBUTOR AND CHECK FOR SPARK NO SPARK CHECK FOR SPARK AT COIL WIRE WITH TIMING LIGHT WHILE CRANKING LEAVE TIMING LIGHT CONNECTED TO COIL WIRE FOR STEPS 3 6 NO SPARK DISCONNECT DISTRIBUTOR 2 WIRE TERMINAL e C PNK BRN CONNECTOR IGNITION SWITCH ON ENGINE STOPPED CHECK FUEL SPARK PLUGS ETC SEE TROUBLESHOOTING REPLACE MAGNETIC SHAFT ASSEMBLY INSPECT CAP FOR WATER CRACKS ETC IF OK REPLACE ROTOR e CHECK VOLTAGE AT BRN AND C PNK TERMI NALS OF DISTRIBUTOR HARNESS CONNECTION BOTH TERMINALS 10 4 VOLTS OR MORE e RECONNECT DISTRIBUTOR 2 TERMINAL CONNECTOR WITH IGNITION ON CHECK VOLT AGE FROM TACH TERMINAL TO GROUND OVER 10 VOLTS CONNECT TEST LIGHT FROM TACH TERMINAL TO GROUND e CRANK ENGINE AND OBSERVE LIGHT CHART CONTINUED ON PAGE 77 90 823224 2 796 BOTH TERMINALS UNDER 10 VOLTS
45. are called a word A word therefore con tains some combination of eight binary code bits eight ones eight zeros five ones and three zeros and so on Binary code is used inside a computer and between a computer and any electronic device that under stands the code By stringing together thousands of bits computers can communicate and store an infi nite variety of information To a computer that under stands binary 11001011 might mean that it should re set engine RPM at a lower level Although the computer uses 8 bit digital codes internally and when talking to another computer each bit can have a meaning Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULE SWITCH TYPES Switched inputs also known as discretes to the computer can cause one bit to change resulting in in formation being communicated to the computer Switched inputs can come in two types they are pull up and pull down types Both types will be discussed With a pull up type switch the ECM will sense a volt age when the switch is CLOSED With the pull down switch the ECM recognizes the voltage when the switch is OPEN Discretes can also be used to inform a computer of FREQUENCY information PULSE COUNTERS Forthe computer to determine frequency information from a switched input the computer must measure the time between voltage pulses As a number of pulses are recorded in a set amount of time the com puter can calculate the
46. at idle air control IAC valve gt N 72800 Throttle Body Idle Air Control IAC Valve O Ring Screws O OO 3 Remove IAC from throttle body CLEANING AND INSPECTION 1 Remove and discard sealing O ring from IAC valve Clean sealing surfaces pintle valve seat and air passage with a carburetor cleaner to re move carbon deposits being careful not to push or pull on the IAC valve pintle Force exerted on the pintle might damage the worm drive DO NOT use a cleaner that contains the extremely strong solvent methyl ethyl ketone NOTE Shiny spots on the pintle or seat are normal and do not indicate misalignment or a bent pintle shaft 2 Inspect the entire assembly for any obvious physical damage Index 5C 180 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY INSTALLATION IMPORTANT If installing a new IAC valve be sure to replace it with an identical part IAC valve pintle shape and diameter are designed for the specific application 1 Install new O ring on IAC valve 72800 Throttle Body Idle Air Control IAC Valve O Ring Screws O O 2 Install IAC valve in throttle body using screws Torque to 20 Ib in 2 N m 3 Installthrottle body throttle linkage and flame ar restor as outlined in Throttle Body 4 Reset IAC valve pintle position a Turn ignition key ON for ten seconds b Turn ignition key OFF for ten seconds
47. from fuel rail Remove inlet and outlet fuel lines from fuel rail 4 lt 5 o 72915 a Fuel Rail b Fuel Inlet Line C Fuel Outlet Line d O Rings e Fuel Line Retainer f Screw g Fuel Rail Mounting Screws 90 823224 2 796 4 Remove fuel rail mounting screws o When facing front of engine remove fuel rail as follows NOTE The left bank fuel injectors are to remain fully seated in the fuel rail throughout removal while the right bank fuel injectors are to remain fully seated in the intake manifold throughout removal a Working from front of engine to rear slide the first front right bank fuel injector from the fuel rail Next slide the first front left bank fuel in jector from the intake manifold Continue slid ing fuel injectors from their respective bores working back and forth toward rear of engine until fuel rail is free 72798 a Fuel Rail b Intake Manifold c Front Right Bank Fuel Injector d Front Left Bank Fuel Injector CLEANING AND INSPECTION Inspect fuel injector seating area in fuel rail for pitting nicks burrs or irregularities use a magnifying glass if necessary If any of the above is present replace the fuel rail Index 90 823224 2 796 ELECTRONIC FUEL INJECTION INSTALLATION NOTE Before installing fuel injectors lubricate new fuel injector O rings using a water soap solution 1 When standing at front of engine install fuel rail as fo
48. has not moved on the wire If boot to wire movement has occurred the boot will give a fast visual impression of being seated To make sure that boots have been properly installed push sideways on them If they have been correctly installed the boots will fit tightly with only a slight looseness If the terminal has not been firmly seated on the spark plug only the re sistance of the rubber boot will be felt when pushed sideways REMOVAL 1 Disconnect spark plug wires from spark plugs 2 Remove spark plugs CLEANING AND INSPECTION 1 Clean spark plugs and spark plug wires with a dry cloth 2 Check each spark plug for wear and gap width per MerCruiser specifications Replace any which fail to meet the standards Check spark plug wires for damage to insulation boots and connectors Replace if necessary 90 823224 2 796 INSTALLATION 1 Install spark plugs Torque to 11 Ib ft 15 N m 2 Connect spark plug wires to their respective spark plug IMPORTANT Wire routing must be kept intact during service and followed exactly when wires have been disconnected or when wire replace ment is necessary Failure to route wires properly can lead to radio frequency interference cross firing of the plugs and or shorting of leads to ground NOTE When replacing spark plug wires it is good practice to replace one wire at a time to reduce the risk of error REMOVAL AND INSTALLATION 1 Disconnect one spark plug
49. high impedance digital multimeter In series with the test light being tested and pow er the test light ammeter circuit with the vehicle battery a Test Light b Battery IMPORTANT If the ammeter indicates LESS than 3 10 amp current flow 3 A or 300 mA the test light is SAFE to use If the ammeter indicates MORE than 3 10 amp cur rent flow 3 A or 300 mA the test light is NOT SAFE to use NOTE Using a test light with 100 mA or less rating may show a faint glow when test actually states no light 13 When using a DVOM to perform voltage mea surements turn the ignition OFF when connect ing the DVOM to the circuitry to be tested T AND THROTTLE BODY 5C 9 Electronic Control Module ECM and Sensors General Description The MerCruiser Electronic Fuel Injection system is equipped with a computer that provides the operator with state of the art control of fuel and spark delivery Computers use voltage to send and receive informa tion Computers and Voltage Signals Voltage is electrical pressure Voltage does not flow in circuits Instead voltage causes current Current does the real work in electrical circuits It is current the flow of electrically charged particles that ener gizes solenoids closes relays and lights lamps Besides causing currents in circuits voltage can be used as a signal Voltage signals can send informa tion by changing levels changing waveform shape or changin
50. mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 43 Knock Sensor KS Circuit Non Scan 2 of 2 e DISCONNECT 5 WAY KS MODULE CONNECTOR e USING DVM MEASURE RESISTANCE BETWEEN TERMINAL E AND GROUND e RESISTANCE SHOULD BE BETWEEN 3 3KO AND 4 5 OHMS IS IT e RECONNECT 5 WAY KS MODULE CONNECTOR CHECK FOR OPEN OR SHORT DISCONNECT KNOCK SENSOR HARNESS CONNECTOR CONNECT A TEST LIGHT TO BATTERY POSITIVE BATTERY POSITIVE B START ENGINE HOLD ENGINE SPEED STEADY AT 2500 RPM REPEATEDLY TOUCH TEST LIGHT TO KNOCK SENSOR HARNESS CONNECTOR TERMINAL CKT 496 DOES A NOTICEABLE RPM DROP OCCUR OR USING TIMING LIGHT DID TIMING DROP IN CKT 496 IF OK REPLACE KNOCK SENSOR YES IGNITION OFF INSPECT KNOCK SENSOR TERMINAL DISCONNECT ECM CONNECTOR J 2 ENCORE T IF OK REPLACE KNOCK IGNITION ON CONNECT DVOM FROM ECM HARNESS CONNECTOR TERMINAL C CKT 485 TO GROUND ARE 8 10 VOLTS PRESENT YES e ALLOW DVM VOLTAGE TO STABILIZE e TOUCH A TEST LIGHT CONNECTED TO TO THE KNOCK SENSOR HARNESS CONNECTOR TERMINAL CKT
51. pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULI 2S AND THROTTLE BODY 5C 119 SURGES continued ADDITIONAL CHECKS FOR Proper alternator output voltage Leaks or kinks in vacuum lines Power reduction mode activated if equipped Clean and tight ECM grounds and in their proper locations Index 5C 120 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 HESITATION SAG OR STUMBLE Definition Momentary lack of response as the throttle is opened Can occur at all engine speeds May cause engine to stall if severe enough PRELIMINARY CHECKS Perform the visual physical checks as described at the start of Troubleshooting Charts section CHECK FUEL SYSTEM FOR 1 Water contaminated fuel and dirty or restricted fuel filter 2 Fuel pressure within specification 3 Proper functioning of fuel injectors 4 Worn throttle linkage CHECK IGNITION SYSTEM FOR 1 Ignition Control IC system for proper timing and advancing 2 Faulty spark plug wires fouled or improperly gapped spark plugs 3 Power reduction mode activated if equipped 4 Knock Sensor KS system operational Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION ES AND THROTTLE BODY 5C 121 HESITATION SAG OR STUMBLE continued CHECK SENSORS AND CONTROLS FOR Binding or sticking Throttle Position TP sensor or salt corrosion Throttle Position TP sensor voltage should increa
52. reading incorrectly and indicating to the ECM that coolant temperature was at 20 F but actual coolant temperature was 175 F This would cause the ECM to deliver more fuel than was actually need ed and result in an overly rich rough running condi tion This condition would not have caused a code to set as the ECM interprets this as within its range To identify a sensor which is out of range unplug it while running the engine After approximately two minutes the diagnostic code for that sensor will set a code and replace the sensed value with a default value If at that point a noticeable performance in crease is observed the non scan code chart for that particular sensor should be followed to correct the problem NOTE Be sure to clear each code after disconnect ing and reconnecting each sensor Failure to do so may result in a misdiagnosis of the problem T AND THROTTLE BODY 5C 7 Special Tools Minimum 10 megohm input impedance required on High Impedance Multi all voltage ranges As ammeter accurately mea meter DVM sures low value current flow As ohmmeter reads 0 200 ohms 2 20 200 2 20 J 34029 A Note 1 Vacuum Pump with Gauge 20 In Hg Minimum J 34142 B Note 2 Unpowered Test Light to check circuit wiring short to ground or volt 91 99379 Timing Light Used to check ignition timing Must have inductive signal pickup 91 16850A 1 Fuel Pressure Gauge Used to check fuel system press
53. screws Torque to 20 Ib in 2 N m 3 Connect electrical connector to IAC valve 73757 a Knock Sensor 2 Remove knock sensor from engine block a Throttle Body b Idle Air Control IAC Valve Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 175 CLEANING AND INSPECTION 1 Clean knock sensor with a dry cloth paying spe cial attention to threads on base 2 Inspect surfaces of knock sensor for signs of wear or physical damage INSTALLATION IMPORTANT If installing a new knock sensor be sure to replace it with an identical part Knock sensors are very sensitive and designed for each specific application IMPORTANT In the following step it is very im portant that the knock sensor be torqued to the precise specification Incorrect torquing will re sult in unsatisfactory performance DO NOT use sealer on threads IMPORTANT Ensure that the knock sensor is installed in the upper location on the Y fitting 1 Install knock sensor in engine block Torque to 12 16 Ib ft 16 3 21 7 N m a Knock Sensor 2 Connect electrical connector to knock sensor Index 5C 176 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Multi Port Injection Components CLEANING AND INSPECTION Manifold Absolute Pressure MAP 1 Clean off any foreign matter with a dry cloth Sensor 2 Inspect for any obvious signs of physical damage to the sens
54. should increase as throttle is moved toward Wide Open Throttle WOT Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT x Es AND THROTTLE BODY 5C 123 DETONATION SPARK KNOCK continued CHECK ENGINE FOR Low oil level Excessive oil in the combustion chamber Valve seals for leaking Perform a compression test Combustion chambers for excessive carbon build up Remove carbon with top engine cleaner Proper camshaft timing Incorrect basic engine parts such as cam heads pistons etc Index 5C 124 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 LACK OF POWER SLUGGISH OR SPONGY Definition Engine delivers less than expected power Little or no increase in speed when throttle control is moved toward Wide Open Throttle WOT PRELIMINARY CHECKS Perform the careful visual physical checks as described at the start of Troubleshooting Charts section Remove flame arrestor and check for dirt or for being plugged Replace as necessary CHECK FUEL SYSTEM FOR 1 Dirty or plugged water separating fuel filter Contaminated fuel Possible open in injector driver CKTs 467 or 468 Improper fuel pressure Flooded VST if equipped CHECK IGNITION SYSTEM FOR 1 Proper initial engine timing 2 Secondary ignition voltage 3 Proper operation of Ignition Control IC Knock Sensor KS open or short to ground in CKT 423 or 485 will set a DTC 42 or 43 Index 9
55. the ECM to cease engine operation until the position of the switch is restored to its normally open position and the ignition key switch has been cycled TEST DESCRIPTION 1 If a Lanyard Stop was recognized by the ECM cycling the ignition will clear the Lanyard Stop condition in the ECM 2 This step checks to see if the Lanyard Stop switch is in the correct position If the switch is closed a Lanyard Stop condition will exist 3 This step checks for Lanyard Stop switch or Lan yard Stop circuitry that is shorted to ground Index 5C 80 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 942 PNK Jj 71 07 LANYARD STOP SWITCH CIRCUIT 1996 AND EARLIER MODELS 4 This step identifies which half of the circuitry is shorted to ground i e ECM side or switch side 5 This step identifies if the circuitry or ECM is the cause of the short to ground DIAGNOSTIC AIDS An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness 90 823224 2 796 Lanyard Stop Emergency Stop Circuit Chec
56. thermistor to control the signal voltage to the Elec tronic Control Module ECM The ECM applies a voltage about 5 volts on CKT 472 to the sensor When the air is cold the sensor thermistor resis tance is high therefore the ECM will see a high sig nal voltage If the air is warm the sensor resistance is low therefore the ECM will see a low voltage TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 A Code 23 will set due to an open sensor wire or connection This test will determine if the wir ing and ECM are OK If the scan tool indicates a temperature of over 266 F 130 C the jumper harness to the sensor should be checked before replacing the sensor 2 This will determine if the IAT sensor signal CKT 472 or the IAT sensor ground CKT 813 is open 3 This step will determine if the fault is in the IAT sensor or the circuit Index 5C 104 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY IAT SENSOR SIGNAL 472 TAN 5V REFERENCE 813 BLK SENSOR GROUND DIAGNOSTIC AIDS The scan tool reads temperature of the air entering the engine and should read close to ambient air tem perature when engine is cold and rises as engine compartment temperature increases The IAT sensor in this engine is located on the star board underside of the plenum Carefully check harness and connections for pos sible open If the engine has been allowed to sit overnigh
57. two throttle plates throttle plate linkage idle air control IAC valve and throttle position TP sensor Service Precautions Always disconnect battery cables from battery BEFORE working on fuel system to prevent fire or explosion Index 5C 154 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Be careful when cleaning flame arrestor and crankcase ventilation hose gasoline is extreme ly flammable and highly explosive under certain conditions Be sure that ignition key is OFF DO NOT smoke or allow sources of spark or open flame in area when cleaning flame arrestor and crankcase ventilation hose Be careful when changing fuel system compo nents gasoline is extremely flammable and high ly explosive under certain conditions Be sure that ignition key is OFF DO NOT smoke or allow sources of spark or open flame in the area while changing fuel filter s Wipe up any spilled fuel immediately Be sure that the engine compartment is well ven tilated and that no gasoline vapors are present to avoid the possibility of fire Make sure no fuel leaks exist before closing en gine hatch CAUTION Fuel pressure MUST BE relieved before servicing high pressure component in the fuel system CAUTION DO NOT operate engine without cooling water being supplied to water pickup holes in gear housing or water pump impeller will be damaged and subsequent overheating damage to engine may result The following inf
58. voltage will be low and Code 42 will be set If the IC line is grounded the ignition module will switch to IC but because the line is grounded there will be no IC signal A Code 42 will be set Index 5C 94 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY DISTRIBUTOR 4 TERMINAL CONNECTOR 423 WHT 430 PPL WHT IGNITION CONTROL IC 12 8 DIST REFERENCE HIGH 424 TAN BLK 453 BLK RED 12 6 DIST REFERENCE 66 LOW TO IN LINE HARNESS TACH TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 Code 42 means the ECM has seen an open or short to ground in the IC or bypass circuits This test confirms Code 42 and that the fault causing the code is present 2 Check for a normal IC ground path through the ignition module An IC CKT 423 shorted to ground will also read more than 3000 ohms how ever this will be checked later 3 As the test light voltage touches CKT 424 the module should switch causing the DVM reading to go from over 3000 ohms to under 1000 ohms Theimportantthing is that the module switched 4 The module did not switch and this step checks for e IC CKT 423 shorted to ground e Bypass 424 open e Faulty ignition module connection or module 5 Confirms that Coded 42 is a faulty ECM and not an intermittent in CKT 423 or CKT 424 90 823224 2 796 Code 42 IC Circuit Non Scan 2 of 2 DIAGNOSTIC AIDS An intermitte
59. wire at spark plug and distributor 2 Connect new spark plug wire at spark plug and distributor 3 Continue steps 1 and 2 until all spark wires have been replaced Engine Rotation and Firing Order Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULI AND THROTTLE BODY 5C 187 THIS PAGE IS INTENTIONALLY BLANK TO ALLOW FOR CORRECTIONS OR ADDITIONS AT A LATER DATE Index 5C 188 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 THIS PAGE IS INTENTIONALLY BLANK TO ALLOW FOR CORRECTIONS OR ADDITIONS AT A LATER DATE Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 189 THIS PAGE IS INTENTIONALLY BLANK TO ALLOW FOR CORRECTIONS OR ADDITIONS AT A LATER DATE Index 5C 190 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796
60. 0 823224 2 796 ELECTRONIC FUEL INJECTION MULT m AND THROTTLE BODY 5C 125 LACK OF POWER SLUGGISH OR SPONGY continued CHECK SENSORS AND CONTROLS FOR 1 Possible open in Engine Coolant Temperature ECT and Manifold Absolute Pressure MAP sensors Ground CKT 814 Also could have and set a DTC 14 and or 33 Throttle Position TP sensor circuit if DTC 21 set for open or grounds Using a scan tool and or voltmeter record Throttle Position TP sensor voltage It should read less than 7 volt with throttle closed or at idle position A sticky throttle shaft or binding linkage causes a high voltage Power reduction mode activated Diagnostic test CKT 451 for being grounded maximum RPMs be will lower CHECK ENGINE FOR 1 Restricted exhaust system 2 Proper cylinder compression Proper valve timing and worn camshaft ADDITIONAL CHECKS Proper alternator output voltage Clean tight and properly located ECM grounds Excessive resistance on bottom of boat dirt barnacles etc Proper size and pitch propeller for application Index 5C 126 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 CUTS OUT AND MISSES Definition Steady pulsation or jerking that follows engine speed usually more pronounced as engine load increases PRELIMINARY CHECKS Perform the important preliminary checks as described at the start of the Troubleshooting Charts section CHECK IGNITION SYS
61. 16 Fuel Pump Fuse 15 Amp 17 Injector Fuse 15 Amp ECM DLC Battery 18 ECM Fuse 10 Amp ECM Ignition Injector Knock Sensor Module 19 Harness Connector to Starting Charging Har ness 20 Harness Connector to Lanyard Stop Switch Optional 21 Harness Connector for Dual Engine Data Link Cable 1996 1 2 And Earlier Models 22 Positive Power Wire to Engine Circuit Breaker OONOORWND Index 90 823224 2 796 ELECTRONIC FUEL INJECTION ey AND THROTTLE BODY 5C 39 Multi Port Injection Wiring Diagram Chart 1 Of 4 INJECTORS 2 3 5 8 RES 67 DK BLU ENGINE 450 BLK WHT FUSE L a50BLKAVHT 10A INJECTORS 1 4 6 7 asi 314 468 DK GR TO IGNITION E 901 WHT RELAY A 901 WHT 902 D 465 DK GRNAWHT Lou 339 PNK BLK FUEL PUMP RELAY FUSE 15A FUEL PUMP RELAY E _ Or PUMP 120 GRY BLK 150 441 BLU WHT IDLE AIR 442 BLU BLK CONTROL IAC VALVE 443 GRN WHT 444 GRN BLK DUAL ENGINE DATA LINK zio gs MULTIPLE ENGINE APPLICATION SOME MODELS CA SOME MODELS WILL HAVE THE 916 YEL 461 ORN BLK 916 YEL DUAL ENGINE SE DATA LINK DLC _ MOVED TO THE MEC a p i 450 BLK WHT TO ED 451 WHT BLK 15 v 440 t 419 BRN WHT Index 5C 40 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY ECM 32 21 INJECTOR DRIVER 12 15 INJECTOR GROUND 42 20 INJECTOR GROUND 25 INJECTOR DRIVER J2 7 PORT FUEL JUMPER
62. 3 Fuel Pump Relay 14 Ignition System Relay 15 Fuse 15 Amp Fuel Pump 16 Fuse 15 Amp ECM DLC Battery 17 Fuse 10 Amp ECM Injector Ignition Knock Module 18 Harness Connector To Starting Charging Har ness 19 Positive Power Wire To Engine Circuit Breaker Index 90 823224 2 796 ELECTRONIC FUEL INJECTION THROTTLE BODY 5C 37 MCM 7 4LX Multi Port Injection 454 502 Magnum Multi Port Injection MIE 454 Tournament Ski Multi Port Injection 502 Magnum Multi Port Injection ANd DNW 2 13 m 2 l 71692 NOTE All BLACK wires with a ground symbol are interconnected within the fuel injection system harness NOTE 1 As amid year 1996 1 2 model change the Multi Port Injection models have the lanyard stop connector removed from the wiring harness The dual engine capability is relocated by routing the YEL wire to the Data Link Connector DLC Index 5C 38 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Vapor Separator Tank VST Throttle Body Distributor Coil Knock Sensor KS Module Data Link Connector DLC Manifold Absolute Pressure MAP Sensor Intake Air Temperature IAT Sensor Knock Sensor 10 Idle Air Control IAC 11 Throttle Position TP Sensor 12 Engine Coolant Temperature ECT Sensor 13 Electronic Control Module ECM 14 Fuel Pump Relay 15 Ignition Relay
63. 496 DOES THE VOLTAGE VALUE CHANGE CONNECT A TEST LIGHT TO GROUND DISCONNECT KS MODULE HARNESS CONNECTOR TOUCH THE TEST LIGHT TO KS MODULE HARNESS CONNECTOR TERMINAL B CKT 439 IS THE TEST LIGHT YES YES NO DISCONNECT KS MODULE HARNESS FAULTY ECM CKT 485 OPEN REPAIR OPEN OR OR SHORTED TO GROUND GROUNDED OR CKT 439 FAULTY KS MODULE CONNECTOR CONNECT A TEST LIGHT TO BATTERY POSITIVE B TOUCH THE TEST LIGHT TO KS HARNESS CONNECTOR TERMINAL D CKT 486 IS THE TEST LIGHT ON YES NO CKT 496 OPEN REPAIR OPEN OR GROUND CKT SHORTED TO GROUND 486 OR FAULTY KS MODULE Index 5 m 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x Es AND THROTTLE BODY 5C 97 Code 51 Calibration Memory Failure Non Scan Diagnostics 1 of 2 CIRCUIT DESCRIPTION This test allows the ECM to check for a calibration failure by comparing the calibration value to a known value stored in the EEPROM This test is also used as a security measure to pre vent improper use of calibrations or changes to these calibrations that may alter the designed function of the EFI system TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step checks to see if the fault is present dur ing diagnosis If present the ECM is not function ing correctly and must be replaced IMPORTANT At the time of printing vessels with Fuel Injection were not b
64. AL CKT 496 DOES A NOTICEABLE RPM DROP OCCUR OR USING TIMING LIGHT DID TIMING DROP IF OK REPLACE KNOCK SENSOR YES IGNITION OFF INSPECT KNOCK SENSOR TERMINAL DISCONNECT ECM CONNECTOR J 2 IF OK REPLACE KNOCK IGNITION ON CONNECT DVOM FROM ECM HARNESS CONNECTOR TERMINAL CKT 485 TO GROUND ARE 8 10 VOLTS PRESENT YES e ALLOW DVM VOLTAGE TO STABILIZE e RAPIDLY TOUCH A TEST LIGHT CONNECTED TO BATTERY POSITIVE B TO THE KNOCK SENSOR HARNESS CONNECTOR TERMINAL CKT 496 DOES THE VOLTAGE VALUE CHANGE CONNECT A TEST LIGHT TO GROUND DISCONNECT KS MODULE HARNESS CONNECTOR TOUCH THE TEST LIGHT TO KS MODULE HARNESS CONNECTOR TERMINAL B CKT 439 IS THE TEST LIGHT ON YES YES NO DISCONNECT KS MODULE HARNESS FAULTY ECM CKT 485 OPEN REPAIR OPEN OR OR SHORTED TO GROUND GROUNDED OR CKT 439 FAULTY KS MODULE CONNECTOR CONNECT A TEST LIGHT TO BATTERY POSITIVE B TOUCH THE TEST LIGHT TO KS HARNESS CONNECTOR TERMINAL D CKT 486 IS THE TEST LIGHT YES NO CKT 496 OPEN REPAIR OPEN OR GROUND CKT SHORTED TO GROUND 486 OR FAULTY KS MODULE Index x 90 823224 2 796 ELECTRONIC FUEL INJECTION x Es AND THROTTLE BODY 5C 111 Code 51 Calibration Memory Failure Scan 1 Of 2 CIRCUIT DESCRIPTION This test allows the ECM to check for a calibration failure by comparing the calibration value to a known value stor
65. ALS SHOULD BE LESS THAN 25 000 OHMS SEE TABLE FOR APPROXIMATE TEMPERATURE TO RESISTANCE VALUES REPLACE SENSOR Q CHECK FOR SIGNAL CIRCUIT BEING SHORTED TO VOLTAGE IF NOT SHORTED TO VOLTAGE CODE 23 IS INTERMITTENT BELOW 4 VOLTS e CHECK VOLTAGE BETWEEN HARNESS CONNECTOR SIGNAL CIRCUIT AND GROUND 4 VOLTS OR OVER BELOW 4 VOLTS FAULTY SENSOR GROUND CIRCUIT OR FAULTY CONNECTION S OR OR FAULTY ECM OR FAULTY ECM IAT SENSOR TEMPERATURE TO RESISTANCE VALUES Index 90 823224 2 796 APPROXIMATE 100 700 ELECTRONIC FUEL INJECTION MUL OPEN SIGNAL CIRCUIT FAULTY CONNECTION Code 33 Manifold Absolute Pressure MAP Sensor Circuit Non Scan 1 Of 2 MAP SENSOR MANIFOLD ABSOLUTE PRESSURE VACUUM TO ECT SENSOR CIRCUIT DESCRIPTION The Manifold Absolute Pressure MAP sensor re sponds to changes in manifold pressure vacuum The ECM receives this information as a signal volt age that will vary from about 1 1 5 volts at closed throttle idle to 4 4 8 volts at Wide Open Throttle W O T low vacuum If the MAP sensor fails the ECM will substitute a fixed MAP value and use the engine RPM to control fuel delivery TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step will determine if there is an adequate vacuum supply to the MAP sensor If the gauge reading is erratic refer to Stallin
66. AYED DOES A CUSTOMER COMPLAINT OR REFER TO APPLICABLE 2 DRIVEABILITY PROBLEM CURRENTLY EXIST SCAN CODE CHART START WITH LOWEST YES TNO CODE FIRST REFER TO TROUBLE FAULT IS NOT SHOOTING SECTION PRESENT AT THIS TIME Index Bm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x E AND THROTTLE BODY 5C 51 No Malfunction Indicator Lamp Marine Diagnostic Code Tool Installed Chart A 1 1 of 2 DUAL ENGINE DATA LINK DUAL ENGINE APPLICATION T ONLY T DLC CONNECTOR ECM DLC 15AMP FUSE ECM INJECTOR KNOCK DIAGNOSTIC SENSOR MODULE CODE TOOL 10 AMP FUSE MALFUNCTION INDICATOR LAMP CIRCUIT DESCRIPTION There should always be a steady Malfunction Indi cator Lamp when the ignition is ON and engine stopped Ignition voltage is supplied directly to the light bulb The Electronic Control Module ECM will control the light and turn it ON by providing a ground path through CKT 419 to the ECM TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step insures that battery voltage is available to terminal F of the DLC connector 2 This step checks for ground present in DLC con nector terminal E This indicates that the ECM is capable of completing the ground to the Mal function Indicator Lamp 3 This step isolates the cause of incomplete ground to either a wiring or ECM circuitry 4 Ifthe engine fails to crank thi
67. Absolute Pressure MAP sensors The IAT sensor is a 2 wire sensor that measures the temperature of the air entering the intake manifold The IAT sensor is a thermistor that changes its resis tance depending on the air temperature When the temperature is low the resistance is high and when the temperature is high the resistance is low The Manifold Absolute Pressure MAP sensor is a 3 wire sensor that monitors the changes in intake manifold pressure which results from changes in en gine loads These pressure changes are supplied to the ECM in the form of electrical signals As intake manifold pressure increases vacuum de creases the air density in the intake manifold also increases and additional fuel is required The MAP sensor sends this pressure information to the ECM and the ECM increases the amount of fuel injected by increasing the injector pulse width As manifold pressure decreases vacuum increases the amount of fuel is decreased These three inputs MAP IAT and RPM are the major determinants of the air fuel mixture delivered by the fuel injection system The remaining sensors and switches provide electri cal inputs to the ECM which are used for modification of the air fuel mixture as well as for other ECM con trol functions such as Idle Air Control IAC 90 823224 2 796 ECM Input and Sensor Descriptions The following lists the sensors switches and other inputs used by the ECM to control its va
68. BLE OR INCORRECT IDLE STALLING continued CHECK SENSORS AND CONTROLS FOR Proper Idle Air Control IAC operation Possible open the in following circuits for CKTs 410 417 416 813 and 814 Possible short to ground in CKT 417 Throttle Position TP sensor signal CKT 416 Throttle Position TP sensor 5 volt reference and CKT 451 diagnostic test circuit A sticking throttle shaft binding linkage or salt corrosion will cause a high Throttle Position TP sensor voltage open throttle indication the ECM will not control idle Using a scan tool or volt meter record Throttle Position TP sensor voltage It should read approximately 7 volt closed throttle and approximately 4 5 volts at Wide Open Throttle WOT CHECK ENGINE FOR 1 Proper cylinder compression 2 Proper camshaft or weak valve springs ADDITIONAL CHECKS oticking or binding throttle linkage and salt corrosion Proper alternator output voltage Battery cables and ground straps should be clean and secure Erratic voltage will cause ldle Air Control IAC to change its position resulting in poor idle quality Index 5C 130 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 BACKFIRE INTAKE Definition Fuel ignites in the manifold making a loud popping noise PRELIMINARY CHECKS Perform the important preliminary checks as described at the start of Troubleshooting Charts section CHECK FUEL SYSTEM FOR 1 An abnorma
69. CE Refer to Service Precautions in Repair 2 Connect electrical connector to the KS module Procedures BEFORE proceeding REMOVAL 1 Remove KS module from electrical bracket 72801 a Electrical Bracket Knock Sensor Module 72801 a Electrical Bracket b Knock Sensor Module 2 Disconnect electrical connector at Knock Sensor KS module CLEANING AND INSPECTION 1 Clean the external surfaces of the KS module with a dry cloth 2 Inspect surfaces of KS module for evidence of damage Index 5C 182 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 ELECTRICAL BOX TYPICAL Bracket Relay Relay Screw Knock Sensor KS Sensor Screw Slave Solenoid Nut Circuit Breaker 10 Screw 11 Screw 12 MerCathode 13 Data Link Connector DLC 14 Circuit Breaker Fuse 15 Circuit Breaker Fuse 16 Circuit Breaker Fuse 17 Screw 18 Nut 19 Engine Control Module ECM O1 O Index 90 823224 2 796 ELECTRONIC FUEL INJECTION 72801 AND THROTTLE BODY 5C 183 Fuel Pump Relay NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Detach fuel pump relay from bracket 72801 a Fuel Pump Relay b Bracket 2 Disconnect electrical connector and remove fuel pump relay IMPORTANT The fuel pump relay is an electrical component D
70. CONNECT IGNITION MODULE 4 WAY CONNECTOR LIGHT ON LIGHT OFF CKT 424 SHORTED FAULTY IGNITION TO GROUND MODULE YES G e RECONNECT ECM AND IDLE ENGINE FOR ONE MINUTE OR UNTIL MALFUNCTION IN DICATOR ON NO FAULTY ECM CODE 42 INTERMITTENT REFER TO DIAGNOSTIC AIDS ON FACING PAGE NOTE CLEAR DIAGNOSTIC TROUBLE CODE DTC STOP ENGINE FOR AT LEAST ONE MINUTE AFTER REPAIR IS PER FORMED RESTART ENGINE AND CHECK FOR CODES Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT Code 43 Knock Sensor KS Scan 1 Of 2 TO SYSTEM RELAY INJ ECM FUSE 15A 439 PNK BLK KNOCK SIGNAL MODULE KNOCK SENSOR 485 BLK KS SIGNAL 486 BRN mb 496 DK BLU CIRCUIT DESCRIPTION Sensing engine detonation or spark knock is accom plished with a module that sends a voltage signal to the ECM As the knock sensor detects engine knock the voltage from the KS module to the ECM drops and this signals the ECM to retard timing The ECM will retard the timing when knock is detected and RPM is above a certain value TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step determines if there is a problem in the circuit When an KS circuit fails the ECM will switch to a default value of about 3 2 degrees of timing retard 2 This step checks if there is a voltage source to the knock sensor from the KS module 3 This step will determine if the kn
71. D IN CKT 339 REPAIR SHORT TO AND REPLACE FUSE CHECK FOR OPEN WIRE IN CKT 120 OPEN PUMP GROUND CKT 150 IF OK REPLACE FUEL PUMP REPAIR OPEN GROUND CKT 450 a CHECK FOR OPEN IN CKT 465 IF OK REPLACE ECM ELECTRONIC FUEL INJECTION MUL zx AND THROTTLE BODY 5C 71 EFI System Ignition Relay Check 1 of 2 TO IN LINE BOAT HARNESS 50A CIRCUIT BREAKER CIRCUIT DESCRIPTION Battery voltage is constantly supplied to terminal 30 of the system relay When the ignition switch is moved to the run position battery voltage is supplied to terminal 86 of the system relay The pull in coil is then energized creating a magnetic field which closes the contacts of the system relay Voltage and current are then supplied to the ignition coil injectors ECM and fuel pump relay fuse through terminal 87 of the system relay TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step identifies if the relay is functioning prop erly If afaultin the relay circuit were present volt age would not be available at terminal B of the ignition coil Index 5C 72 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY SYSTEM RELAY ENGINE TO ECM TERM GROUND n TO IGN COIL 15A TERM B INJ ECM KS MODULE FUSE 10A 2 This step ensures that battery and ignition volt age are available at the relay An open or shorted condition in
72. E INSTALL FUEL PRESSURE GAUGE AND NOTE PRESSURE WHILE CRANKING ENGINE SHOULD BE 36 PSI 248 kPa NOMINAL Index 90 823224 2 796 REVIEW THE DIAGNOSTIC AIDS ON FACING PAGE FOR ADDITIONAL ITEMS TO CHECK IF ALL ARE OK EFI SYSTEM IS OK REFER TO HARD START IN THE TROUBLESHOOTING SECTION Engine Cranks but Will Not Run Continued Chart A 3 3 of 4 INJECTORS C GBRE 481 RED 2 mg lt a genes mmx lt A E MULTI PORT TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 Check for 12 volt supply to injectors Due to the injectors wired in parallel there should be a light ON on both terminals Check continuity of CKT 467 and CKT 468 All checks made to this point would indicate that the ECM is at fault However there is a possibility of CKT 467 or CKT 468 being shorted to a voltage source either in the engine harness or in the injec tor harness Index 5C 58 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 439 PNK BLK 21 11 IGNITION FEED INJECTOR DRIVER 467 DK BLU ENGINE GROUND 423 WHT 430 PPL WHT 424 TAN BLK 453 BLI RED THROTTLE BODY To test for this condition e Disconnect all injectors e Ignition ON e Probe 467 and 468 on the ECM side of injector harness with a test light con nected to ground Test one injector harness on each side of engine There should be
73. ED DURING CRANKING NOTE 2 IS NOT AVAILABLE PLACE THE LANYARD STOP SWITCH IN THE RUN POSITION BLINKING LIGHT USING AN INDUCTIVE PICKUP TIMING USING AN INDUCTIVE PICKUP TIMING LIGHT LIGHT CONNECTED TO ANY SPARK CONNECTED TO ANY SPARK PLUG WIRE PLUG WIRE CHECK FOR SPARK CHECK FOR SPARK WHILE CRANKING WHILE CRANKING CHECK TWO WIRES CHECK TWO WIRES IS SPARK PRESENT IS SPARK PRESENT YES NO YES IGNITION OFF e DISCONNECT DISTRIBUTOR 4 WAY CONNECTOR IGNITION ON e MOMENTARILY TOUCH HARNESS CONNECTOR TERMINAL CKT 430 WITH A TEST LIGHT TO 12 VOLTS SCAN TOOL OR TACHOMETER SHOULD INDICATE RPM WHEN TEST IS PERFORMED DOES IT BASIC HEI PROBLEM REFER TO 2 CHECK FOR BATTERY VOLTAGE TO IGNITION SYSTEM IF OK THERE IS A BASIC HEI DISCONNECT ALL INJECTORS CONNECT TEST LIGHT J 34730 2 OR EQUIVALENT TO INJECTOR HARNESS CONNECTOR TEST ONE INJECTOR HARNESS FROM EACH GROUPING OF INJECTORS CHECK FOR BLINKING LIGHT WHILE CRANKING IGNITION SYSTEM CHECK PROBLEM THEN REFER TO IGNI TION SYSTEM CHECK NO BLINKING LIGHT REFER TO LANYARD STOP CIRCUIT CHECK CHECK RESISTANCE ACROSS NO BLINKING LIGHT EACH INJECTOR AND COMPARE VALUES USE CHART s FAULTY CONNECTION IS RESISTANCE 12 OHMS t 4 A 3 40F4 OR IGNITION MODULE GROUND OR FAULTY ECM w REPLACE INJECTOR S IGNITION OFF THAT IS OUT OF RANG
74. ED TO GROUND VOLTS OR FAULTY ECM CKT 814 OPEN OR FAULTY ECM YES NO YES e DISCONNECT e TOUCH TEST LIGHT CKT 432 CONNECTED TO BATTERY POSITIVE FAULTY TO VOLTAGE FAULTY CONNECTION AT ECM OR FAULTY ECM TO HARNESS TERMINAL B IS TEST LIGHT ON SEE NOTE CKT 432 SHORTED FAULTY ECM TO GROUND NOTE USING A TEST LIGHT WITH 100 mA OR LESS RATING MAY SHOW A FAINT GLOW WHEN TEST ACTUALLY STATES NO LIGHT Index x 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x AND THROTTLE BODY 5C 93 Code 42 Ignition Control IC Circuit Non Scan 1 of 2 CONNECTOR IGN PICK UP COIL GRY CONNECTOR IGNITION CONTROL IC TACH IGNITION COIL MODULE CONNECTOR DISTRIBUTOR TO SYSTEM RELAY 4 CONNECTOR 121 GRY 121 WHT TO DISTRIBUTOR GRY CONNECTOR CIRCUIT DESCRIPTION When the system is running on the ignition module that is no voltage on the bypass line the ignition module grounds the IC signal The ECM expects to detect no voltage on the IC line during this condition If it detects a voltage it sets Code 42 and will not go into the IC mode When the RPM for IC is reached about 300 RPM and bypass voltage applied the IC should no longer be grounded in the ignition module so the IC voltage should be varying If the bypass line is open or grounded the ignition module will not switch to IC mode so the IC
75. ELAY To GRY CONNECTOR CONNECTOR oru REC TO TACH GRY CONNECTOR TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 5C 74 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Two spark plug wires are checked to ensure that an open is not present in a spark plug wire If spark occurs with Ignition Control IC connec tor disconnected magnetic field output is too low for Ignition Control IC operation A spark indicates the problem must be the distrib utor cap or rotor Normally there should be battery voltage at the and terminals Low voltage would indicate an open or a high resistance circuit from the dis tributor to the coil or ignition switch If C terminal voltage was low but terminal voltage is 10 volts or more circuit from C terminal to ignition coil or ignition coil primary winding is open Index PICK UP COIL C GBRE DISTRIBUTOR 4 TERMINAL CONNECTOR 423 WHT 430 PPLWWHT IGNITION CONTROL 12 8 DIST REFERENCE HIGH 424 TAN BLK 453 BLK RED 42 6 DIST REFERENCE LOW Checks for a shorted module or grounded circuit from the ignition coil to the module The distribu tor module should be turned OFF so normal volt age should be about 12 volts If the module is turned ON the voltage would be low but above 1 volt This could cause the igni tion coil to fail from excessive heat With
76. ETURN WITHIN 75 RPM OF RECORDED RPM WITHIN 30 SECONDS DOES IT YES NO IAC CIRCUIT FUNCTIONING PROPERLY 2 IGNITION OFF FOR 10 SECONDS UNPLUG IAC CONNECTOR IF CONNECTED RESTART ENGINE WITH A TEST LIGHT CONNECTED TO GROUND PROBE EACH ONE OF THE FOUR IAC TERMINALS AND THE TEST LIGHT SHOULD BLINK WHEN TOUCHED TO ALL TERMINALS DOES IT No YES STICKY OR CHECK IAC CIRCUIT FAULTY THAT DID NOT BLINK FOR OPEN OR SHORTED kasa FROM IAC HARNESS TO J 2 CONNECTOR CIRCUIT IF OK REPLACE ECM Index Lm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL IESS z amp AND THROTTLE BODY 5C 79 Lanyard Stop Circuit Check Emergency Stop Circuit Check 1 of 2 NORMALLY OPEN f LANYARD STOP SWITCH B BLK NOTE Some models are no longer equipped with this option in the wiring harness Connection of the lanyard stop switch if equipped is performed at the instrument panel CIRCUIT DESCRIPTION The Lanyard Stop circuit is a safety feature incorpo rated in boats to stop the engine in the event that the operator is removed from a safe control position dur ing normal operation The Lanyard Stop switch is a normally open switch that is physically connected to the operator by a tether In the event that the operator is removed from a control position the tether con nected to the switch will be pulled out closing the switch This information from the Lanyard Stop switch will then be used by
77. FUEL SYSTEMS m z x E MULTI PORT AND THROTTLE BODY FUEL INJECTION Index Table of Contents General Information Introduction Visual Physical Inspection Basic Knowledge and Tools Required Electrostatic Discharge Damage Diagnostic Information Wiring Harness Service Wiring Connector Service Abbreviations Changes In Terminology Diagnostic Trouble Codes ECM Self Diagnostics Diagnostic Code Tool With Malfunction Indicator Intermittent Malfunction Indicator Lamp Reading Codes Scan Tools EFI Diagnostic Circuit Check Scan Tool Use with Intermittents With No Codes Set Special Tools Service Precautions Electronic Control Module ECM and Sensors General Description Computers and Voltage Signals Analog Signals Digital Signals Engine Control Module ECM Speed Density System ECM Input and Sensor Descriptions Spark Management High Energy Ignition with Ignition Control C Modes Of Ope
78. Gasket 14 Throttle Position TP Sensor 5 Upper O Ring 15 Screws 2 6 Fuel Meter Outlet Gasket 16 Seal 7 Fuel Injector 2 17 O Ring 8 Fuel Filter 2 18 Idle Air Control IAC Valve 9 Lower O Ring 19 Screws 2 10 Screw 20 Fuel Inlet Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT m AND THROTTLE BODY 5C 149 Fuel Pressure Relief Procedure NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding Disconnect electrical connector from fuel pump 2 Crank engine for ten seconds if engine starts al low it to run until it dies to relieve any fuel pres sure in the system Fuel Meter Cover Assembly NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding CAUTION DO NOT remove the four screws securing the pressure regulator to the fuel meter cover The fuel pressure regulator includes a large spring under heavy compression which if accidentally released could cause personal injury REMOVAL 1 Remove the flame arrestor from the throttle body 2 Disconnectelectrical connectors to fuel injectors Squeeze plastic tabs and pull straight up 3 Remove the fuel meter cover screw assemblies Index 5C 150 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 4 Remove fuel meter cover assembly 73767 Fuel Meter Cover Fuel Damper Gaskets Regulator Passages Screws Fuel Meter Outlet Gasket
79. I PORT AND THROTTLE BODY 2 Remove pressure regulator attaching screws and nuts and remove pressure regulator 29 V a Fuel Rail b Pressure Regulator C Screw d Filter e O Rings f Nut 3 Carefully remove filter from fuel rail using an awl or equivalent tool CLEANING AND INSPECTION 1 Inspect pressure regulator seating area on fuel rail for pitting nicks burrs or irregularities Use a magnifying glass if necessary If any of the above is present replace the fuel rail 2 Clean filter of any debris using solvent Dry using compressed air INSTALLATION 1 Install filter into appropriate bore of fuel rail 2 Install new pressure regulator O rings using a water and soap solution 3 Carefully slide pressure regulator into fuel rail 4 Apply Loctite 8831 to threads of attaching screws Install screws and nuts and torque to 88 124 Ib 10 14 N m 5 Install fuel rail plenum throttle body and flame arrestor as outlined in this section 6 With engine OFF cycle ignition switch to ON wait 2 seconds and then OFF four times waiting 10 seconds after each key off to prime the fuel sys tem and check for leaks 90 823224 2 796 Fuel Injectors NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL NOTE Use care in removing fuel injectors to prevent damage to the electrical connector and nozzle IMPORTANT The fuel injector is a
80. IC operation are known as the bypass and IC circuits Modes Of Operation There are two modes of ignition system operation DISTRIBUTOR MODULE MODE The ignition system operates independent of the ECM The distributor module module in the distribu tor maintains a base ignition timing and is able to ad vance timing to a total of 27 degrees This mode is in control when a Code 42 is detected while engine is running and will have a noticeable affect on engine operation ECM CONTROL MODE The ECM control mode controls the ignition timing The ECM calculates the desired ignition timing based on information it gets from its input sensors Index 5C 18 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Distributor Module Mode The following describes IC operation during cranking and when the engine starts running To help under stand how IC circuits operate a relay with a double set of contact points is shown in the IC module refer to the figures Ignition Control Mode and ECM Con trol Mode Solid state circuitry is used in the module but showing the relay makes it easierto visualize how the IC module functions During cranking the relay is in the de energized posi tion see figure Distributor Module Mode This con nects the pickup coil to the base of the transistor via the signal converter When the pickup coil applies a positive voltage to the transistor the transistor turns ON When voltage is removed
81. ITION OFF 10 SECONDS CHART A 7 APPLY 12 VOLTS TO FUEL PRESSURE ABOVE NO 38 PSI 262 kPa PRESSURE q IGNITION ON 4O0F6 PUMP CONNECTOR GRAY BLOCK FUEL PRESSURE LINE USING WIRE OK NOT OK SPECIAL TOOL SHUT OFF VALVE LISTEN FOR FUEL PUMP RUNNING PRESSURE SHOULD HOLD NO TROUBLE FOUND REVIEW THE TROUBLE NOT HOLDING HOLDS SHOOTING SECTION IGNITION OFF FOR 10 SECONDS CHECK e USING AN EXTERNAL e IGNITION ON e LEAKING PUMP FITTINGS VACUUM SOURCE APPLY 10 INCHES OF VACUUM TO FUEL PRESSURE REGULATOR e FUEL PRESSURE SHOULD DROP 3 10 PSI 21 69 kPa e BLOCK FUEL RETURN LINE USING OR HOSE SPECIAL TOOL SHUT OFF VALVE e FAULTY VST PUMP RECHECK PRESSURE NOT OK HOLDS NOT HOLDING REPAIR VACUUM REPLACE FAULTY FUEL PRESSURE 4 LOCATE AND CORRECT SOURCE TO REGULATOR REGULATOR LEAKING INJECTOR S REGULATOR ASSEMBLY PUMP NOT RUNNING CHECK FOR CHECK FOR e RESTRICTED FUEL LINE e OPEN WIRE IN 120 e DISCONNECTED HOSE e OPEN PUMP GROUND CKT 150 REPLACE ELECTRIC FUEL PUMP Index Lm 90 823224 2 796 ELECTRONIC FUEL INJECTION I AND THROTTLE BODY 5C 61 Multi Port Injection Fuel System Diagnosis Continued Chart A 7 3 of 6 RETURN SUPPLY Injector Filter ONE PIECE FUEL RAIL ASSEMBLY Typical Fuel Pressure Fuel Pressure Service Tap Regulator Filter Fuel Pressure Regula
82. Ignition wires for cracking hardness and proper The importance of this step cannot be stressed too routing strongly it can lead to correcting a problem without 5 Wiring for proper connections pinches and cuts further checks and can save valuable time i me If wiring harness or connector repair is neces 1 Ensure that engine is in good mechanical condi sary tion Index 5C 114 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Troubleshooting Charts IMPORTANT PRELIMINARY CHECKS BEFORE USING THIS SECTION Before using this section you should have performed the EFI Diagnostic Circuit Check and de termined that 1 The ECM is operating correctly 2 There are no diagnostic trouble codes DTC stored SYMPTOM Verify the customer complaint and locate the correct symptom Check the items indicated under that symptom VISUAL PHYSICAL CHECK Several of the symptom procedures call for a careful visual physical check The importance of this step cannot be stressed too strongly It can lead to correcting a problem without further checks and can save valuable time These checks should include 1 ECM grounds and sensors for being clean tight and in their proper locations Vacuum hoses for splits kinks and proper connections Check thoroughly for any type of leak or restriction Air leaks at throttle body mounting area and intake manifold sealing surfaces Ignition wires for crac
83. K GRN WHT RELAY DRIVER 450 BLK WHT 1 120 GRY 150BLK FUEL PUMP TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step checks if there is power to the fuel pump relay 2 Bypassing the relay circuit should cause the fuel pump to run This step should identify if the fault is in the relay or in the fuel pump circuit 3 This step checks if there is an open in the ground circuit 4 Thisstep checks if the ECM is functioning proper ly Index 5C 64 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Multi Port Injection Fuel System Diagnosis Continued Chart A 7 6 of 6 FROM CHART A 7 IGNITION OFF REMOVE FUEL PUMP RELAY IGNITION ON WITH TEST LIGHT CONNECTED TO GROUND PROBE FUEL PUMP RELAY CONNECTOR CAVITY 30 TEST LIGHT SHOULD BE ON IS IT YES NO IGNITION OFF USING FUSED JUMPER CONNECT CHECK FUEL PUMP RELAY FUSE TERMINALS 30 AND 87 OF FUEL IS IT OK PUMP RELAY CONNECTOR TOGETHER IGNITION FUEL PUMP SHOULD RUN DOES IT YES NO REPAIR OPEN CKT 339 OR 902 YES NO REPAIR SHORT TO GROUND IN CKT 339 AND REPLACE FUSE IGNITION OFF DISCONNECT FUSED JUMPER CONNECT TEST LIGHT TO BATTERY POSITIVE AND PROBE CAVITY 86 OF THE CHECK FOR e OPEN WIRE IN 120 e OPEN PUMP GROUND 150 IF OK REPLACE FUEL PUMP FUEL PUMP
84. MINAL CONNECTOR 423 WHT IGNITION CONTROL IC 430 PPLWHT 32 8 DIST REFERENCE HIGH 424 TAN BLK 453 BLIURED 12 6 DIST REFERENCE LOW 121 WHT IN LINE HARNESS TACH TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 Code 42 means the ECM has seen an open or short to ground in the IC or bypass circuits This test confirms Code 42 and that the fault causing the code is present 2 Check for a normal IC ground path through the ignition module An IC CKT 423 shorted to ground will also read more than 3000 ohms how ever this will be checked later 3 As the test light voltage touches CKT 424 the module should switch causing the DVOM read ing to go from over 3000 ohms to under 1000 ohms The important thing is that the module switched 4 The module did not switch and this step checks for e IC CKT 423 shorted to ground e Bypass CKT 424 open e Faulty ignition module connection or module 5 Confirms that Coded 42 is a faulty ECM and not an intermittent in CKT 423 or CKT 424 90 823224 2 796 Code 42 IC Circuit Scan 2 of 2 DIAGNOSTIC AIDS Refer to Intermittents in Troubleshooting An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire e CLEAR CODES e IDLE ENGINE FOR 1 MINUTE OR UNTIL CODE 42 SETS
85. MPERATURE SCAN DISPLAY LESS THAN 22 F 30 e IGNITION OFF e DISCONNECT COOLANT TEMPERATURE SENSOR JUMPER TERMINALS A AND B TOGETHER e IGNITION ON e SCAN TOOL SHOULD DISPLAY COOLANT TEMPERATURE ABOVE 266 F 130 C DOES IT CKT 410 OPEN REPLACE ENGINE OR COOLANT SENSOR GROUND TEMPERATURE OPEN SENSOR OR FAULTY ECM ELECTRONIC FUEL INJECTION MULT zx AND THROTTLE BODY 5C 101 Code 21 Throttle Position TP Sensor Circuit Scan 1 of 2 FRONT VIEW OF CONNECTOR THROTTLE POSITION SENSOR CIRCUIT DESCRIPTION The Throttle Position TP Sensor provides a voltage signal that changes as throttle blades open or close Signal voltage should vary from about 7 volts at idle to about 4 5 volts at Wide Open Throttle W O T The TP signal is one of the most important inputs used by the Electronic Control Module ECM for fuel control and for most of the ECM controlled outputs TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 With throttle closed the TP sensor should read between 3 and 8 volt If it does not check throttle cable adjustment or for bent linkage 2 Withthe TP sensor disconnected the TP voltage should go low if the ECM and wiring are OK 3 Probing CKT 813 with a DVOM to CKT 416 checks the sensor ground A faulty sensor ground will cause a Code 21 Index 5C 102 ELECTRONIC FUEL INJECTION MULTI PORT
86. Multi Port Injection Fuel System Diagnosis Chart A 7 1 of 6 SUPPLY LINE RETURN LINE Injector Filter Fuel Injector CIRCUIT DESCRIPTION During engine cranking the Engine Control Module ECM will turn ON the electric fuel pump in the vapor separator tank It will remain ON as long as the en gine is cranking or running and the ECM is receiving reference pulses If there are no reference pulses the ECM will shut OFF the fuel pump The pump will deliver fuel to the fuel rail and injectors then to the pressure regulator where the system pressure is controlled to about 36 PSI 248 kPa nominal Excess fuel is then returned to the vapor separator tank TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 If pump does not run check fuel pump relay and fuse 2 Wrapa shop towel around the fuel pressure con nector to absorb any small amount of fuel leak age that may occur when installing the gauge Index 5C 60 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY ONE PIECE FUEL RAIL ASSEMBLY Typical Fuel Pressure Fuel Pressure Service Regulator Filter Fuel Pressure Regulator ra Heference Line to Plenum Ignition ON pump pressure should be 34 38 PSI 234 262 kPa This pressure is controlled by spring pressure within the regulator assembly When the engine is idling high vacuum is applied to the fuel regulator diaphragm This w
87. N N N co N O O 1 Cover Torque Sequence For VST 2 Seal 3 Spring 4 Diaphragm 5 O ring 6 Diaphragm Cover Screw 8 Valve Seat 9 Float Valve 10 Float Valve Pin 11 Clip 12 Float 13 Float Arm Pin 14 VST Body 73805 15 Fuel Screen 16 Plate a Tighten Screws Securely 17 Rubber Cushion 18 Electric Fuel Pump 19 Plate 20 O ring 21 Adapter 22 O ring 23 Oollar 24 O ring 25 Adapter 26 Lockwasher 2 Screw 28 O ring 29 Insulator 30 Lockwasher 31 Nut 32 Electrical Connector 33 Screw 34 Lockwasher 35 L Joint 36 O ring 37 O ring 38 Nut 39 Lockwasher 40 Insulator 41 O ring 42 Screw 43 Grommet 44 Lockwasher 45 Clip 46 Lockwasher 47 Screw 48 Plug 49 O ring a A VST equipped with elbow fitting on top of VST will have this configuration diaphragm and spring Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULI AND THROTTLE BODY 5C 139 VST Fuel Pump Exploded View Collar O Rings 2 Adapters 2 O Ring Plate Electric Fuel Pump Rubber Cushion Plate Fuel Filter Seal 11 Chamber Body 12 O Rings 2 O Index 5C 140 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 72803 Insulators 2 Lockwashers 2 Nuts 2 Electrical Connector Screw Spring Washer L Joint O Ring O Ring Cover Screws 6 Lockwashers 6 Clip 90 823224 2 796
88. N FACING PAGE Index 90 823224 2 796 YES No NO 4 DOES THE ENGINE CRANK LOCATE AND CORRECT SHORT TO GROUND IN CIRCUIT REPAIR OPEN OR SHORTED CKT 440 YES NO wa PERFORM TESTS ON i O EOM STARTING SYSTEM CIR C CONNECIORS CUIT SEE TROUBLE CON SHOOTING IN SECTION NO PROBE ECM CONNECTOR PINS J1 16 J1 32 AND J1 11 WITH TEST LIGHT TO GROUND IGNITION OFF IS THE LIGHT ON ON DISCONNECT ECM ALL CIRCUITS J2 CONNECTOR USING DVM MEASURE RESISTANCE YES BETWEEN ECM TERMINAL 5 31 FAULTY ECM GROUNDS PERFORM EFI SYSTEM OR ECM RELAY CHECK DOES ias piis ENGINE START CONNECTOR TERMINAL E RESISTANCE SHOULD BE CLOSE YES TO 0 OHMS IS IT REPEAT STEP 1 REPAIR OPEN IN CIRCUIT OF THIS CHART THAT DID NOT LIGHT THE TEST LIGHT YES FAULTY ECM CHECK FOR SHORT IN CONNECTIONS OR WIRE 419 BETWEEN J2 31 FAULTY ECM AND DLC TERMINAL E ELECTRONIC FUEL INJECTION MUL zx AND THROTTLE BODY 5C 53 No DLC Data or Will Not Flash Code 12 Malfunction Indicator Lamp On Steady Marine Diagnostic Code Tool Installed Chart A 2 1 of 2 DUAL ENGINE DATA LINK DUAL ENGINE APPLICATION E ONLY DLC CONNECTOR TO ECM 10A BATTERY FUSE TO SWITCHED IGNITION MARINE DIAGNOSTIC CODE TOOL MALFUNCTION INDICATOR LAMP CIRCUIT DESCRIPTION There should always be a steady Malfunction Indi cator Lamp when the ignition is ON and engine stopped Ignition
89. NAL CKT 432 OPEN OR SHORTED TO GROUND YES NO FAULTY CONNECTION FAULTY MAP SENSOR OPEN SENSOR GROUND CIRCUIT FAULTY ECM Index 90 823224 2 796 ELECTRONIC FUEL INJECTION zx AND THROTTLE BODY 56 107 Code 42 Ignition Control IC Circuit Scan 1 Of 2 aux CONNECTOR IGN GRY CONNECTOR IGNITION COIL CONNECTOR ACH IGNITION CONTROL GBRE DISTRIBUTOR TO SYSTEM RELAY I GRY CONNECTOR 3 PNK BLK CONNECTOR 121 GRY pcc ur dcr rm TO DISTRIBUTOR GRY CONNECTOR CIRCUIT DESCRIPTION When the system is running on the ignition module that is no voltage on the bypass line the ignition module grounds the IC signal The ECM expects to detect a low voltage on the IC line during this condi tion If it detects a voltage it sets Code 42 and will not go into the IC mode When the RPM for IC is reached about 300 RPM and bypass voltage applied the IC should no longer be grounded in the ignition module so the IC voltage should be varying If the bypass line is open or grounded the ignition module will not switch to IC mode so the IC voltage will be low and Code 42 will be set If the IC line is grounded the ignition module will switch to IC but because the line is grounded there will be no IC signal A Code 42 will be set Index 5C 108 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY PICK UP COIL DISTRIBUTOR 4 TER
90. NG RUN ON Definition Engine continues to run after key is turned OFF but runs very roughly If engine runs smoothly check ignition switch and adjustment PRELIMINARY CHECKS Perform the important preliminary checks as described at the start of Troubleshooting section CHECK FUEL SYSTEM FOR 1 Leaking injectors 2 Flooded VST CHECK IGNITION SYSTEM FOR 1 Properly functioning advancing and retarding of timing Ignition Control IC 2 Correct heat range spark plugs 3 Proper operation of system relay CHECK COOLING SYSTEM FOR 1 Faulty or incorrect thermostat 2 Cooling system restriction causing overheating 3 Loose belts Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT AND THROTTLE BODY 5C 133 POOR FUEL ECONOMY Definition Fuel economy is noticeably lower than expected PRELIMINARY CHECKS Perform the important preliminary checks as described at the start of Troubleshooting section 1 Operator s driving habits 2 Dirty or plugged flame arrestor 3 Fuelleaks CHECK FUEL SYSTEM FOR 1 Quality and type of fuel 2 Flooded VST 3 Fuel pressure within specification CHECK IGNITION SYSTEM FOR Correct base timing Properly functioning advancing and retarding of timing Ignition Control IC Fuel fouled cracked worn improperly gapped spark plugs burned electrodes or heavy depos its Repair or replace as necessary Knock sensor system operation
91. NSOR MULTI PORT INJECTION MODELS ONLY The Intake Air Temperature IAT sensor is a thermis tor a resistor which changes value based on temper ature mounted on the underside of the plenum Low temperature produces a high resistance while high temperature causes a low resistance 13047 a Intake Air Temperature IAT Sensor b Harness Connector c Locking Tab Index 5C 14 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY The ECM supplies a 5 volt signal to the sensor through a resistor in the ECM and measures the volt age The voltage will be high when the intake air is cold and low when the intake manifold air is hot A failure in the IAT sensor circuit should set a Code 23 MANIFOLD ABSOLUTE PRESSURE MAP SENSOR The Manifold Absolute Pressure MAP sensor is a pressure transducer that measures the changes in the intake manifold pressure The pressure changes as aresult of engine load and speed change and the MAP sensor converts this to a voltage output 73046 a Manifold Absolute Pressure MAP Sensor b Electrical Connector A closed throttle on engine coast down would pro duce a relatively low MAP output voltage while a wide open throttle would produce a high MAP output voltage This high output voltage is produced be cause the pressure inside the manifold is the same as outside the manifold so 100 of outside air pres sure is measured When manifold pressure is high vacuum is low
92. O NOT soak in any liquid cleaner or solvent damage may result INSTALLATION 1 Insert electrical connector into fuel pump relay 2 Attach fuel pump relay to bracket Index 5C 184 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Ignition Control IC System Components Precautions When performing the following procedures be sure to observe the following precautions to avoid damage to equipment or personal injury DO NOT touch or disconnect any ignition system parts while the engine is running DO NOT reverse battery cable connections Sys tem is negative ground DO NOT disconnect battery cables while engine is running When it is necessary to move any of the wiring whether to lift wires away from their harnesses or move harnesses to reach components take care that all wiring is replaced in its original position and all harnesses are routed correctly Electrical problems can result from wiring or harnesses be coming loose and moving from their original positions or from being re routed 90 823224 2 796 Ignition Coil NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Disconnect wire harness connectors at coll 72921 Wire Harness Connection High Tension Coil Lead Connection O f m Remove high tension coil lead p Remove coil bracket fasteners and remove coll bracket with coil Index 90 823224 2 796 ELEC
93. ODE No fuel is delivered by the injectors when the ignition is OFF to prevent dieseling Also fuel pulses are not delivered if the ECM receives no distributor reference pulses which means the engine is not running The fuel cutoff mode is also enabled at high engine RPM as an overspeed protection for the engine When cut off is in effect due to high RPM injection pulses will resume after engine RPM drops slightly Index 90 823224 2 796 ELECTRONIC FUEL INJECTION POWER REDUCTION MODE 1996 AND OLDER MODELS The ECM will go into power reduction mode when the following conditions are met 1 Low oil pressure 2 Engine overheat Low I O fluid level 4 High transmission temperature MIE The ECM recognizes change of state in a discrete switch input that identifies an abnormal condition that may affect proper drive train operation As an engine protection feature power reduction mode allows normal fuel injection up to 2800 RPM Above 2800 RPM fuel delivery is limited to half of the injectors until RPM lowers to 1200 RPM when normal fuel injection resumes This feature maintains maneuverability of the vessel while removing the possibility of high RPM operation until the problem is corrected DECELERATION MODE The IAC is similar to a carburetor dashpot It provides additional air when the throttle is rapidly moved to the idle position to prevent the engine from dying sy AND THROTTLE BODY
94. ODY 90 823224 2 796 5 Remove TP with O ring and IAC valve with O ring from throttle body a Throttle Position TP Sensor b Idle Air Control IAC valve CLEANING AND INSPECTION IMPORTANT DO NOT use cleaners containing methyl ethyl ketone It is not necessary for clean ing throttle bore and valve deposits IMPORTANT DO NOT allow the TP and IAC valve to come into contact with solvent or cleaner IMPORTANT Use care when removing gasket material from plenum and throttle body Failure to do so could result in damage to the plenum and throttle body 1 Carefully remove all gasket material from plenum and throttle body 2 Thoroughly clean all parts of throttle body Make certain that all passages are free of dirt and burrs 3 Inspect mating surfaces for damage that could affect gasket sealing Inspect throttle body for cracks in casting Inspect throttle plates linkage return springs etc for damage wear and foreign material 6 Check plenum for loose parts and foreign materi al Index 90 823224 2 796 ELECTRONIC FUEL INJECTION INSTALLATION NOTE To prevent difficult removal of fasteners and damage to fastener heads do not use a higher strength thread locking compound than recom mended 7 Connect TP and IAC electrical connectors then install throttle body with new gasket using four throttle body mounting studs TA S l 5 222 n M
95. RELAY CONNECTOR LIGHT SHOULD BE ON IS IT NO CONNECT TEST LIGHT TO GROUND AND PROBE CAVITY 85 OF THE FUEL PUMP RELAY CONNECTOR IGNITION ON TEST LIGHT SHOULD BE FOR 2 SECONDS AND THEN GO OFF DOES IT REPLACE FUEL PUMP RELAY AND RETEST IF STILL NO PRESSURE CHECK THE FOLLOWING CHECK FOR OPEN VAPOR LOCK CONDITION IN CKT 465 IF OK RESTRICTED FUEL LINE REPLACE ECM DISCONNECTED HOSES PROPER FUEL LEVEL IF OK REPLACE FUEL PUMP Index Bm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x I2 AND THROTTLE BODY 5C 65 Throttle Body Injection Fuel System Diagnosis Chart A 7 1 of 6 FUEL LINE TO ELECTRIC FUEL PUMP SHUT OFF TOOL IMPORTANT Check for contaminated fuel tank stuck anti siphon valve or fuel system vacuum leak anywhere before the electrical fuel pump and after the fuel pressure regulator CIRCUIT DESCRIPTION During engine cranking the Engine Control Module ECM will turn ON the electric fuel pump It will re main ON as long as the engine is cranking or running and the ECM is receiving reference pulses If there are no reference pulses the ECM will shut OFF the fuel pump The pump will deliver fuel to the injectors and pres sure regulator where the system pressure is con trolled to about 30 PSI 207 kPa nominal Excess fuel is then returned to the water separating fuel filter TEST DESCRIPTION Number s below refer to circled number s on t
96. Step 1 pr Xep xb we De c NOTE When clearing codes without the use of a scan tool the battery must be fully charged The abil ity to clear codes is directly dependent on the battery being fully charged and able to start the engine with adequate cranking RPM Index 90 823224 2 796 ELECTRONIC FUEL INJECTION ML Non Scan Diagnosis of Driveability Concerns With No Codes Set If a driveability concern still exists after following the diagnostic circuit check and reviewing Trouble shooting an out of range sensor may be sus pected Because of the unique design of the EFI sys tem fail safes have been incorporated into the ECM to replace a sensed value with a default value in the case of a sensor malfunction or sensor wiring con cern By allowing this to occur limited engine perfor mance is restored until the vessel is repaired A basic understanding of sensor operation is necessary in or der to diagnose an out of range sensor If the sensor is within its working or acceptable pa rameters as shown the ECM does not detect a prob lem If the sensor should happen to fall out of this window a code will be stored A known default val ue will replace the sensed value to restore engine performance If the sensor is out of range but still within the operat ing window of the ECM the problem will go unde tected by the ECM and may result in trouble later A good example of this would be if the coolant sensor was
97. T 4 WAY CONNECTOR NOTE OHM METER THAT IS STILL CONNECTED TO CKT 423 AND GROUND RESISTANCE SHOULD HAVE GONE HIGH OPEN CIRCUIT DOES IT YES NO CKT 424 OPEN FAULTY CKT 423 CONNECTIONS OR FAULTY SHORTED TO IGNITION MODULE GROUND Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL NO CODE 42 CODE 42 INTERMITTENT IF NO ADDITIONAL CODES WERE STORED REFER TO INTERMITTENTS IN TROUBLE SHOOTING SECTION OR DIAGNOSTIC AIDS ABOVE WHERE APPLICABLE OPEN CKT 423 FAULTY CONNECTION OR FAULTY IGNITION MODULE LIGHT ON e DISCONNECT IGNITION MODULE 4 WAY CONNECTOR LIGHT ON LIGHT OFF CKT 424 SHORTED FAULTY IGNITION TO GROUND MODULE YES e RECONNECT ECM AND IDLE ENGINE FOR ONE MINUTE OR UNTIL MALFUNCTION IN DICATOR LAMP COMES ON LIGHT ON LIGHT OFF CODE 42 CODE 42 INTERMITTENT FAULTY ECM NO TROUBLE FOUND CHECK HARNESS AND CONNECTORS FOR AN INTERMITTENT OPEN OR SHORT TO GROUND IN CKT 423 AND 424 Code 43 Knock Sensor KS Non Scan 1 of 2 INJ ECM tosystem VSE 15A RELAY 439 PNK BLK KNOCK SENSOR MODULE KNOCK SENSOR SIGNAL 485 BLK 486 BRN oe 496 DK BLU KNOCK SENSOR CIRCUIT DESCRIPTION The ability to sense engine knock or detonation is ac complished with a module that sends a voltage signal to the ECM As the knock sensor detects engine knock the voltage from the KS module to
98. T 2 SECONDS NOTE FUEL PRESSURE WITH PUMP RUNNING SHOULD BE 28 32 PSI 193 221 kPa AND HOLD STEADY WHEN PUMP STOPS LOK 2 G PRESSURE BUT PRESSURE BELOW NO TROUBLE FOUND NOT HOLDING 28 PSI 193 kPa REVIEW THE TROUBLE SHOOTING SECTION PRESSURE ABOVE NO 32 PSI 221 kPa PRESSURE REMOVE FLAME ARRESTOR AND VISUALLY Pn 2 CHECK FOR LEAKAGE p FROM INJECTORS IK AM IGNITION OFF e APPLY 12 VOLTS TO FUEL PUMP CONNECTOR GRAY WIRE LEAKAGE NO LEAKAGE e LISTEN FOR FUEL PUMP RUNNING 4 REPLACE LEAKING INSTALL FUEL SHUT OFF TOOL INJECTOR IGNITION OFF FOR 10 SECONDS IGNITION ON BLOCK FUEL RETURN LINE USING SPECIAL TOOL SHUT OFF VALVE PRESSURE SHOULD HOLD NOT HOLDING HOLDS FAULTY FUEL PRESSURE CHECK REGULATOR e LEAKING PUMP FITTINGS OR HOSE e REPLACE FUEL PUMP PUMP NOT RUNNING CHECK FOR CHECK FOR e RESTRICTED FUEL LINE e OPEN WIRE 120 e DISCONNECTED HOSE e OPEN PUMP GROUND CKT 150 REPLACE ELECTRIC FUEL PUMP 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x AND THROTTLE BODY 5C 67 Throttle Body Injection Fuel System Diagnosis Continued Chart A 7 3 of 6 RETURN LINE FROM FUEL PRESSURE REGULATOR WATER SEPARATING FUEL FILTER SHUT OFF TOOL IMPORTANT Check for contaminated fuel tank 2 Restricting the fuel return line Shut Off Valve al stuck anti siphon valve or fuel system vacuum lows the fuel pressure to build abo
99. TAGE OVER 4 VOLTS YES NO YES e IGNITION OFF e CONNECT DVM FAULTY CONNECTION FAULTY CONNECTION e CONNECT A TEST LIGHT BETWEEN HARNESS SEN TO B4 BATTERY POSITIVE TERMINAL AND CIC PATEOBEN OR CKT 813 0 ENGINE GROUND OR TOUCH TEST LIGHT TO IS VOLTAGE OVER 4 OR FAULTY ECM HARNESS TERMINAL C VOLTS SHORTED TO GROUND THROTTLE POSITION i OR SENSOR SIGNAL FAULTY ECM IS TEST LIGHT YES NO CKT 417 SHORTED OPEN CKT 417 TO VOLTAGE OR FAULTY CONNECTION AT ECM YE OR gt NO FAULTY ECM DISCONNECT ECM THROTTLE POSITION e TOUCH TEST LIGHT SENSOR FAULTY CONNECTED TO BAT TERY POSITIVE TO HARNESS TERMINAL C IS TEST LIGHT YES NO CKT 417 SHORTED FAULTY ECM TO GROUND Index Bm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x AND THROTTLE BODY 5C 89 Code 23 Intake Air Temperature IAT Sensor Circuit Non Scan 1 Of 2 INTAKE AIR TEMPERATURE SENSOR CIRCUIT DESCRIPTION The Intake Air Temperature IAT sensor uses a thermistor to control the signal voltage to the Elec tronic Control Module ECM The ECM applies a voltage about 5 volts on CKT 472 to the sensor When the air is cold the sensor thermistor resis tance is high therefore the ECM will see a high sig nal voltage If the air is warm the sensor resistance is low therefore the ECM will see a low voltage TEST DESCRIPTION Number s below refer t
100. TCH Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL AND THROTTLE BODY 5C 85 Diagnostics Without Scan Tool Code 14 Engine Coolant Temperature ECT Sensor Circuit Non Scan 1 of 2 ENGINE COOLANT TEMPERATURE SENSOR TO MAP SENSOR CIRCUIT DESCRIPTION The Engine Coolant Temperature ECT sensor uses a thermistor to control the signal voltage to the ECM The ECM applies a voltage on 410 to the sensor When the engine coolantis cold the sensor thermis tor resistance is high therefore the ECM will see high signal voltage As the engine coolant warms the sensor resistance becomes less and the voltage drops TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step checks if there is a problem with the ECM and wiring or if the problem is the coolant sensor 2 Checkthe harness terminals thoroughly for loose connection If the resistance or the coolant sen sor is monitored the resistance should steadily decrease as the engine coolant warms up The resistance reading would stabilize when the ther mostat opens Index 5C 86 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY ENGINE COOLANT SENSOR SIGNAL 410 YEL 5V 814 BLK SENSOR GROUND 3 This step will isolate the problem to CKT 410 5 volt reference or to the sensor ground 4 This step identifies if CKT 410 is open or shorted to ground DIAGNOSTIC AIDS
101. TEM FOR 1 Cylinder miss a Startengine allow engine to stabilize record RPM then disconnect IAC motor Stop engine ground one spark plug wire at a time Restart engine and record RPM If there is an RPM drop on all cylinders go to Stalling Rough or Incorrect Idle section With engine OFF reconnect IAC motor If there is no RPM drop on one or more cylinders or excessive variation in RPM drop check for spark on the suspected cylinder s If there is a spark remove spark plug s in these cylinders and check for Insulation cracks insulator cracks wear improper gap burned electrodes heavy deposits Spark plug wire resistance should not exceed 30 000 ohms Faulty ignition coil With engine running spray distributor cap and spark plug wires with a fine mist of water to check for shorts CHECK FUEL SYSTEM FOR 1 Contaminated or restricted water separating fuel filter 2 Fuel pressure within specification Fuel pressure can be checked on fuel rail at the schrader valve Mechanical pump can be checked with a carburetor fuel pressure gauge downstream from the pump prior to VST Faulty fuel injectors Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT x ES AND THROTTLE BODY 5C 127 CUTS OUT AND MISSES continued CHECK SENSORS AND CONTROLS FOR 1 Open or grounds 417 Throttle Position TP sensor signal 2 Open or grounds in CKT 416 Throttle Position TP sensor 5 volt r
102. THROTTLE BODY SENSOR GROUND 813 BLK 417 DK BLU TP SIGNAL 5V REFERENCE 416 GRY DIAGNOSTIC AIDS An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared If Code 23 is also set check CKT 813 for faulty wiring or connections Check terminals at sensor for good contact 90 823224 2 796 Code 21 Throttle Position TP Sensor Circuit Non Scan IGNITION OFF DISCONNECT THROTTLE POSITION SENSOR ELECTRICAL CONNECTOR IGNITION ON e CONNECT A DVM FROM HARNESS TERMINAL A 5 VOLT REFERENCE TO HARNESS TERMINAL B SENSOR GROUND IS VOLTAGE READING OVER 4 VOLTS YES NO e CONNECT DVM FROM HARNESS TERMINAL A e CONNECT DVM FROM THROTTLE POSITION CKT 416 TO HARNESS TERMINAL C THROTTLE SENSOR HARNESS TERMINAL A TO A GOOD POSITION SENSOR SIGNAL CKT 417 GROUND ON ENGINE IS VOLTAGE READING OVER 4 VOLTS IS VOL
103. TRONIC FUEL INJECTION RESISTANCE CHECK Use an ohmmeter or the ohms function of a DVM for the following check 1 Connect meter as shown with meter 1 in the fig ure below 72920 2 Setting the meter to its highest ohms scale check resistance The reading should indicate infinite resistance If it does not replace the coil 3 Connect meter as shown with meter 2 in the fig ure above 4 Setting the meter to its lowest ohms scale check resistance The reading should be very low or zero resistance If it is not replace the coil 5 Connect meter as shown with meter 3 in the fig ure above 6 Setting the meter to its highest ohms scale check resistance The reading should not indicate infi nite resistance If it does replace the coll INSTALLATION 7 Install coil bracket with coil to engine bracket us ing fasteners AND THROTTLE BODY 5C 185 8 Connect high tension coil lead 72921 a Wire Harness Connection b High Tension Coil Lead Connection 9 Connect wire harness connectors IGNITION TIMING SET PROCEDURE The engine mustbe at NORMAL OPERATING TEM PERATURE for this adjustment Two items of test equipment are required an inductive pickup timing light and either a Scan Tool Diagnostic Code Tool or MerCruiser Special Timing Tool 91 805747A1 1 Connect timing light to number 1 ignition wire 2 Connect the appropriate tool as listed above to the DLC connector of t
104. TTERY POSITIVE B TOUCH TEST LIGHT TO SENSOR HARNESS TERMINAL B CKT 410 IS TEST LIGHT ON FAULTY CONNECTION AT ECM OR FAULTY ECM YES CKT 410 OPEN e DISCONNECT 1 OR CONNECTOR FAULTY CONNECTION AT ECM IS TEST LIGHT OR FAULTY ECM YES NO CKT 410 SHORTED OE 410 SHORTED TO SENSOR GROUND n FAULTY ECM DIAGNOSTIC AID ECT SENSOR TEMPERATURE TO RESISTANCE VALUES APPROXIMATE 25 000 100 700 Index x m 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x Es AND THROTTLE BODY 5C 87 Code 21 Throttle Position TP Sensor Circuit Non Scan 1 Of 2 FRONT VIEW OF CONNECTOR THROTTLE POSITION SENSOR CIRCUIT DESCRIPTION The Throttle Position TP sensor provides a voltage signal that changes relative to the throttle blade Sig nal voltage should vary from about 7 volts at idle to about 4 5 volts at Wide Open Throttle W O T TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step checks for a voltage from terminal C 5 volt reference to terminal A sensor ground 2 This step will identify if the problem is in the sup ply or ground circuit 3 This step determines if the TP sensor signal cir cuit to the ECM is open 4 This step completes the test for the ECM and wir ing If the test light is not ON the TP sensor has an internal problem Index 5C 88 ELECTRONIC FUEL INJECTION MULTI PORT AND
105. UND ENGINE BLOCK ENGINE OFF IGNITION ON CHECK RESISTANCE FROM OIL PRESSURE SWITCH AND GROUND ENGINE BLOCK RESISTANCE SHOULD BE NEAR ZERO CONTINUITY CIRCUIT DISCONNECT ECM J1 CONNECTOR FROM ECM CHECK REPLACE FAULTY FOR CONTINUITY BETWEEN J1 6 AND TAN BLU WIRE SWITCH IN CIRCUIT FROM OIL PRESSURE SWITCH YES NO DISCRETE INPUT CIRCUIT DISCONNECT IN LINE HARNESS AND CHECK CONTINUITY ON TAN BLU FUNCTIONING PROPERLY WIRE FROM OIL PRESSURE SWITCH TO IN LINE HARNESS CONNECTOR NO CHECK CONTINUITY ON TAN BLU WIRE FROM IN LINE HARNESS REPAIR SHORT CONNECTOR TO J1 6 TERMINAL ON ECM CONNECTOR IN CIRCUIT REPLACE ECM REPAIR SHORT AND RETEST IN CIRCUIT I O LEVEL SWITCH GEAR LUBE MONITOR DISCONNECT TAN BLU WIRE FROM I O OIL LEVEL SWITCH START ENGINE CHECK RESISTANCE FROM TAN BLU WIRE AND BLK GROUND WIRE RESISTANCE SHOULD BE NEAR ZERO DISCONNECT ECM J1 CONNECTOR FROM ECM CHECK REPLACE GEAR FOR CONTINUITY BETWEEN J1 6 AND TAN BLU WIRE LUBE BOTTLE FROM OIL LEVEL SWITCH YES NO DISCRETE INPUT CIRCUIT DISCONNECT IN LINE HARNESS AND CHECK CONTINUITY ON TAN BLU FUNCTIONING PROPERLY WIRE FROM OIL LEVEL SWITCH TO IN LINE HARNESS CONNECTOR NO CHECK CONTINUITY ON TAN BLU WIRE FROM IN LINE HAR REPAIR SHORT CONNECTOR TO J1 6 TERMINAL ON ECM CONNECTOR IN CIRCUIT NESS REPLACE ECM REPAIR SHORT AND RETEST IN CIRCUIT REFER TO REPAIR PORTION OF THIS SECTION FOR TESTING OF TRANSMISSION FLUID TEMPERATURE SWI
106. a 262kPa 2nd 19 PSI 17 PSI 21 PSI 19 PSI 19 PSI 19 PSI 19 PSI 19 PSI Reading 131 kPa 117 145kPa 131 131kPa 131kPa 131 131 kPa Amount of 19 PSI 21 PSI 17 PSI 19 PSI 19 PSI 19 PSI 19 PSI 19 PSI Drop 131 kPa 145 kPa 117 kPa 131 kPa 131 kPa 131 kPa 131 kPa 131 kPa Hich Lean OK Too Much Too Little OK OK OK OK OK Fuel Drop Fuel Drop n d ex 90 823224 2 796 ELECTRONIC FUEL INJECTION z amp AND THROTTLE BODY 5C 35 Wiring Harness Diagrams MCM 7 4LX MIE 7 4L Throttle Body Injection Bluewater Inboard NHO NO IHAV NH9 XQ P CT gs RR NS d NYO LHe 75001 Note All BLACK wires with a ground symbol are interconnected within the fuel injection system harness NOTE 1 As amid year 1996 1 2 model change the Throttle Body Injection models have the lanyard stop con nector removed from the wiring harness The dual engine capability is relocated by routing the YEL wire to the Data Link Connector DLC Index 5C 36 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Fuel Pump Throttle Body Distributor Coil Electronic Spark Control KS Module Data Link Connector DLC Manifold Absolute Pressure MAP Sensor Knock Sensor Idle Air Control IAC 10 Throttle Position TP Sensor 11 Engine Coolant Temperature ECT Sensor 12 Electronic Control Module ECM 1
107. anging the engine operating characteristics Scan Tools The ECM can communicate a variety of information through the DLC connector This data is transmitted at a high frequency which requires a scan tool for in terpretation With an understanding of the data which the tool dis plays and knowledge of the circuits involved the tool can be very useful in obtaining information which would be more difficult or impossible to obtain with other equipment Scan tools do not make the use of diagnostic charts unnecessary nor can they indicate exactly where a problem is in a particular circuit Tree charts incorpo rate diagnosis procedures using a scan tool where possible or a Diagnostic Code Tool non scan if a scan tool is unavailable Index 5C 6 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY EFI Diagnostic Circuit Check After the visual physical inspection the EFI Diagnos tic Circuit Check is the starting point for all diagnostic procedures Refer to EFI Diagnostic Circuit Check The correct procedure to diagnose a problem is to fol low two basic steps 1 Are the on board diagnostics working This is determined by performing the EFI Diagnostic Cir cuit Check Since this is the starting point for the diagnostic procedures always begin here If the on board diagnostics are not working the EFI Diagnostic Circuit Check will lead to a diagnostic chart in Diagnostics to correct the problem If the on board diag
108. arges of the same polarity are drained off leaving the person highly charged with the opposite polarity otatic charges of either type can cause damage therefore it is important to use care when handling and testing electronic components T AND THROTTLE BODY 5C 1 Diagnostic Information The diagnostic charts and functional checks in this manual are designed to locate a faulty circuit or com ponent through logic based on the process of elimi nation The charts are prepared with the require ment that the system functioned correctly at the time of assembly and that there are no multiple failures Wiring Harness Service Marine engine control circuits contain many special design features not found in standard land vehicle wiring Environmental protection is used extensively to protect electrical contacts and proper splicing methods must be used when necessary The proper operation of low amperage input output circuits depends upon good continuity between cir cuit connectors It is important before component re placement and or during normal troubleshooting pro cedures that a visual inspection of any questionable mating connector is performed Mating surfaces should be properly formed clean and likely to make proper contact Some typical causes of connector problems are listed below 1 Improperly formed contacts and or connector housing 2 Damaged contacts or housing due to improper engagement 3 Corrosion seal
109. as _ ast 468 DK GR 25 INJECTOR DRIVER PL ER 901 WHT J2 7 PORT FUEL JUMPER RELAY A 901 WHT 12 22 PORT FUEL JUMPER RE 465 DK GRN WHT 1249 FUEL PUMP RELAY DRIVE R Lou 339 PNK BLK ad FUEL PUMP RELAY FUSE 15A FUEL PUMP RELAY E FUEL PUMP 120 GRY BLK 150 441 BLU WHT 22 28 IAC COIL A HIGH IDLE AIR AR 442 BLU BLK IAC COIL A LOW CONTROL 12 13 IAC VALVE 443 GRN WHT 7 22 14 iac COIL HIGH 444 GRN BLK 12 29 IAC COIL B LOW BLK DUAL ENGINE DATA LINK l MULTIPLE ENGINE 916 YEL MASTER SLAVE APPLICATION SOME MODELS i SOME MODELS WILL HAVE THE 461 ORN BLK 11 18 SERIAL DATA 916 YEL DUAL ENGINE SH DATA LINK DLC MOVED TO THE CONNECTOR 450 BLK AWHT DLC EB TO ECM BAT 451 WHT BLK 31 7 DIAGNOSTIC TEST TERMINAL x FUSE m 15A sje rara L 440 ORN 419 BRN WHT 2231 MALFUNCTION INDICATOR LAMP Index 5C 44 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Throttle Body Injection Wiring Diagram Chart 2 Of 4 813 BLK THROTTLE POSTION SENSOR TP 417 DK BLU 416 GRY 813 BLK 813BLK woo T m PRESSURE ra 432 LT GRN MAP SENSOR A 814 BLK 814 BLK ENGINE COOLANT TEMPERATURE ECT SENSOR 410 YEL Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL ECM THROTTLE POSITION SENSOR SIGNAL 5 VOLTS REFERENCE SENSOR GROUND 5 VOLTS REFERENCE
110. ator spring pressure and intake manifold vacu um on the other The regulator s function is to main tain a constant pressure differential across the injec tors at all times The pressure regulator compensates for engine load by increasing fuel pres sure as engine vacuum drops SSS N WA sss A LL N Mwy fh lt f r 71716 Throttle Body Assembly The throttle body assembly is attached to the ple num and is used to control air flow into the engine thereby controlling engine output The throttle valves within the throttle body are opened by the operator through the accelerator controls During engine idle the throttle valves are almost closed and air flow control is handled by the Idle Air Control IAC valve described below The throttle body also provides the location for mounting the Throttle Position TP sensor for sens ing throttle valve position mmm N a Throttle Body b Idle Air Control IAC Valve C Throttle Position Sensor sy AND THROTTLE BODY 5C 27 IDLE AIR CONTROL IAC VALVE The purpose of the IAC valve assembly is to control engine idle speed while preventing stalls due to changes in engine load The IAC valve mounted in the throttle body controls bypass air around the throttle valves 72800 Idle Air Control IAC Valve Assembly By moving a conical valve known as a pintle IN to ward the seat to d
111. ave this configuration diaphragm and spring Electrical Connector Cover Lockwashers 6 Screws 6 Clip Spring Diaphragm O Ring Diaphragm Cover 10 O Ring 11 Screw 12 Lockwasher O1 ON 90 823224 2 796 L abel and then disconnect all fuel lines from cov er of vapor separator tank Remove electrical line from retainer clip Remove cover screws and remove cover and electrical line retaining clip Remove float arm pin retaining fastener and re move float and needle assembly Remove diaphragm cover screws and remove di aphragm cover O ring diaphragm and spring CLEANING AND INSPECTION 7 Clean and inspect all parts Check diaphragm for damage Replace if necessary 8 Inspect spring for wear Replace if necessary INSTALLATION 1 Install spring diaphragm O ring and diaphragm cover using diaphragm cover screws Tighten screws 2 Install float and needle assembly and secure float arm pin using fastener 3 Apply Loctite 8831 to threads of cover screws Install cover and electrical line retainer clip and tighten cover screws securely 73895 Torque Sequence For VST 4 5 Secure electrical line in retainer clip Connect all fuel lines to cover of vapor separator tank Torque fuel line fittings to 23 Ib ft 31 N m Connect fuel pump electrical connector With engine OFF cycle ignition switch to ON wait for 2 seconds then OFF four times
112. b Knock Sensor KS Sensor Engine Coolant Temperature ECT Sensor NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL NOTE Handle the ECT carefully as any damage to it will affect operation of the system 72799 a Thermostat Housing b Engine Coolant Temperature ECT Sensor 2 Connect electrical connector to ECT Index 5C 172 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Throttle Body Injection Components Manifold Absolute Pressure MAP Sensor NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Disconnect electrical connector at manifold ab solute pressure MAP sensor 493 a Throttle Body Adapter Plate b Manifold Absolute Pressure MAP Sensor 2 Remove MAP sensor from throttle body adapter CLEANING AND INSPECTION 1 Clean off any foreign matter with a dry cloth 2 Inspectfor any obvious signs of physical damage to the sensor INSTALLATION 1 Install MAP sensor to throttle body adapter using screws Torque screws to 44 62 Ib in 5 7 N m Index 90 823224 2 796 ELECTRONIC FUEL INJECTION 2 Connect electrical connector to MAP sensor f UE D 3 Ux e gt N iS a Throttle Body Adapter Plate b Manifold Absolute Pressure MAP Sensor Throttle Position TP Sensor NOTICE Refer to Service Precautions in Repair Procedures
113. clips and rosin core solder g Ft 73048 4 Cover splice with heat shrink sleeve to insulate from other wires pep c3 73048 Wiring Connector Service Most connectors in the engine compartment are pro tected against moisture and dirt which could create oxidation and deposits on the terminals This protec tion is important because of the very low voltage and current levels found in the electronic system The connectors have a lock which secures the male and female terminals together A secondary lock holds the seal and terminal into the connector When diagnosing open circuits are often difficult to locate by sight because oxidation or terminal mis alignment are hidden by the connectors Merely wig gling a connector on a sensor or in the wiring harness may locate the open circuit condition This should al ways be considered when an open circuit or failed sensor is indicated Intermittent problems may also be caused by oxidized or loose connections Before making a connector repair be certain of the type of connector Some connectors look similar but are serviced differently Replacement connectors and terminals are listed in the Parts Catalog Ensure that the connector seals are not deformed or crushed when mating the connectors together 90 823224 2 796 Abbreviations BAT a ee NM System Voltage on OWmde 3G Dee _ ECT Engine Coolant Temperature EEPROM Electronic Erasable P
114. dex 5C 50 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 10 Refer to appropriate Troubleshooting and or Diagnostic Charts NOTE When clearing codes without the use of a scan tool the battery must be fully charged and cranking speed must be at least 300 RPM The ability to clear codes is directly dependent on the battery be ing fully charged and able to start the engine with ad equate cranking RPM A poorly charged battery or engine cranking problem may result in an ECM reset and may not allow stored trouble codes to be cleared from EEPROM memory If this condition exists BE SURE the battery is fully charged If a low battery condition does exists the audio warning buzzer will come on for 2 seconds after engine start up MARINE DIAGNOSTIC CODE TOOL FLASHING CODE 12 CHECK FOR GROUNDED DIAGNOSTIC TEST CKT 451 OR FAULTY TOOL REFER TO APPLICABLE NON SCAN CODE CHART START WITH LOWEST CODE FIRST 90 823224 2 796 CLEARING CODES USING SCAN TOOL SCAN 4 Clear codes 1 Connect scan tool 5 Turn key OFF 2 Start engine 6 Turn key ON and read codes If codes are still present there is a real fault in system check ion Select clear codes function note preceding and repeat Step 1 LINK SCAN TOOL AND CHECK FOR CODES SCAN TOOL DOES SCAN TOOL DISPLAY ECM DATA YES DID ENGINE START PRIOR USE CHART 2 TO DIAGNOSTIC CIRCUIT CHECK B YES ARE ANY CODES DISPL
115. e based on IAC valve pintle position throttle valve stop screws and PCV e Controlled idle speed is programmed into the ECM which determines the correct IAC valve pintle position to maintain the desired idle speed for all engine operating conditions and loads e The minimum idle air rate is set at the factory with stop screws This setting allows enough air flow by the throttle valves to cause the IAC valve pintle to be positioned a calibrated number of steps counts from the seat during controlled idle op eration e fthelAC valve is disconnected and reconnected with the engine running the idle soeed may be wrong In this case the IAC valve can be reset by doing the following turn off engine wait ten se conds and restart engine Index 5C 26 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Multi Port Injection Components FUEL PUMP ELECTRICAL CIRCUIT When the ignition switch is turned to the RUN posi tion the ECM will turn ON the fuel pump relay for two 2 seconds When the ignition switch is turned to the crank posi tion the ECM turns the fuel pump relay ON causing the fuel pump to start If the ECM does not receive ignition reference pulses engine cranking or running it shuts OFF the fuel pump relay causing the fuel pump to stop FUEL RAIL INTAKE MANIFOLD ASSEMBLY The fuel rail performs several functions It positions the injectors in the intake manifold distributes fuel evenl
116. e circuit boards within the ECM The ROM contains the overall control pro grams Once the ROM is programmed it cannot be changed The ROM memory is non erasable and does not need power to be retained RAM Random Access Memory RAM is the microproces sor scratch pad The processor can write into or read from this memory as needed This memory is erasable and needs a constant supply of voltage to be retained EEPROM Electronic Erasable Programmable Read Only Memory EEPROM is the portion of the ECM that contains the different engine calibration information that is specific to each marine application Speed Density System The Electronic Fuel Injection system is a speed and air density system The system is based on speed density fuel management Three specific data sensors provide the ECM with the basic information for the fuel management portion of its operation That is three specific signals to the ECM establish the engine speed and air density fac tors Index 5C 12 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY SPEED The engine speed signal comes from the distributor s High Energy Ignition HEI module to the ECM on the distributor reference high circuit The ECM uses this information to determine the speed or RPM factor for fuel and ignition management DENSITY Two sensors contribute to the density factor the In take Air Temperature IAT Multi Port models only and the Manifold
117. e crank posi tion the ECM turns ON the fuel pump relay and the fuel pump builds up pressure The ECM then checks the Engine Coolant Temperature ECT sensor and Throttle Position TP sensor and determines the proper air fuel ratio for starting The ECM controls the amount of fuel delivered in the starting mode by changing how long the injectors are turned ON and OFF This is done by pulsing the injectors for very short times 90 823224 2 796 CLEAR FLOOD MODE If the engine floods it can be cleared by opening the throttle half way 50 Open throttle handle until re sistance from secondary throttle Multi Port only is felt The ECM discontinues fuel injector pulsation as long as the throttle is between 50 to 75 and the en gine RPM is below 300 If the throttle position be comes more than 75 or less than 5096 the ECM re turns to the starting mode RUN MODE When the engine is started and RPM is above 300 the system operates in the run mode The ECM will calculate the desired air fuel ratio based on these ECM inputs RPM Manifold Absolute Pressure MAP sensor Intake Air Temperature IAT sensor and Engine Coolant Temperature ECT sensor Higher engine load from MAP and colder engine temperature from ECT requires more fuel or a rich er air fuel ratio ACCELERATION MODE The ECM looks at rapid changes in Throttle Position TP and provides extra fuel by increasing the injector pulse width FUEL CUTOFF M
118. e negative battery cable until the module or sensor removed has been re installed with secure connections IMPORTANT Modules and sensors are electrical devices easily damaged by contact with liquid cleaners or solvents Clean with a dry cloth un less specifically directed to do otherwise Electronic Control Module ECM IMPORTANT The ECM is a sensitive electrical de vice subject to electrostatic damage Therefore take care not to touch connector pins when re moving or installing the module Electrical Bracket ECM J1 Electrical Connector Front Connector J2 Electrical Connector Rear Connector NOTICE Refer to Service Precautions in Repair QOO 9 Procedures BEFORE proceeding 2 Remove ECM from electrical bracket CLEANING AND INSPECTION 1 Cleanthe exterior of the ECM with a dry cloth be ing careful to avoid contact with connector pins 2 Inspect outer surfaces for any obvious damage 3 Visually inspect electrical pins at both ends of ECM for straightness and corrosion 4 Visually inspect J1 and J2 connectors on the wir ing harness for corrosion and terminals that may have backed of the harness NOTE The ECM is a sealed electrical component If a Code 51 check has shown it to be defective re place the unit with another ECM having the same part number and service number as the original Index 5C 170 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224
119. eaks around gasket and fuel line couplings Index 5C 152 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Throttle Body REMOVAL CAUTION Ensure that fuel pressure is relieved before re moving the fuel inlet and return lines IMPORTANT DO NOT allow the TP sensor fuel pressure regulator fuel injectors and IAC valve to come into contact with solvent or cleaner These components should be removed prior to immersion in solvent 1 Remove the flame arrestor from the throttle body 2 Disconnect throttle cable 3 Disconnect the electrical connections from the TP sensor IAC and fuel injectors Squeeze plas tic tabs on injectors and pull straight up a Electrical Connections 4 Remove fuel inlet and outlet lines from throttle body 5 Remove screws retaining the throttle body to adapter plate NOTE Place a shop rag over the intake manifold opening to prevent debris from entering intake man ifold 90 823224 2 796 CLEANING AND INSPECTION 1 Thoroughly clean metal parts of throttle body in a cold immersion type cleaner Dry with com pressed air Make certain that all passages are free of dirt and burrs 2 Inspect mating surfaces for damage that could affect gasket sealing 3 Inspect throttle body for cracks in casting 4 nspect throttle plates linkage return springs etc for damage wear and foreign material 5 Check intake manifold plenum for loose parts and foreign mat
120. echnician s ability to understand the system he is trying to diagnose as well as an understanding of the scan tool operation and limitations The techni cian should read the tool manufacturer s operating manual to become familiar with the tool s operation 90 823224 2 796 CLEARING CODES USING DIAGNOSTIC CODE TOOL NON SCAN 1 Install diagnostic code tool Turn key ON Select service mode on code tool To clear codes move the throttle while in neutral from 0 to 10096 then back to 0 Exit Service Mode on code tool Start engine and let run for fifteen seconds Turn key OFF for 5 seconds Select Service Mode on code tool ND Turn key ON and read codes If codes are still present check note following and repeat from otep 1 10 Refer to appropriate Troubleshooting and or Diagnostic Charts A poorly charged battery or engine cranking problem may result in an ECM reset and may not allow stored trouble codes to be cleared from EEPROM memory If this condition exists BE SURE the battery is fully charged NOTE lf a low battery condition does exists the au dio warning buzzer will come on for 2 seconds after engine start up CLEARING CODES USING SCAN TOOL SCAN Connect scan tool otart engine Select clear codes function Clear codes Turn key OFF Turn key ON and read codes If codes are still present there is a real fault in system check fol lowing note and repeat
121. ecrease air flow or OUT away from the seat to increase air flow a controlled amount of air moves around the throttle valve If RPM is too low more air is bypassed around the throttle valve to increase it If RPM is too high less air is by passed around the throttle valve to decrease it The ECM moves the IAC valve in small steps called counts These can be measured by scan tool test equipment which plugs into the DLC connector During idle the proper position of the IAC valve is en gine load and engine RPM If the RPM drops below specification and the throttle valve is closed the ECM senses a near stall condition and calculates a new valve position to prevent stalling e Engine idle speed is a function of total air flow into the engine based on IAC valve pintle position e Controlled idle speed is programmed into the ECM which determines the correct IAC valve pintle position to maintain the desired idle speed for all engine operating conditions and loads e The minimum idle air rate is set at the factory with stop screws This setting allows enough air flow by the throttle valves to cause the IAC valve pintle to be positioned a calibrated number of steps counts from the seat during controlled idle op eration Index 5C 28 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY e Ifthe IAC valve is disconnected and reconnected with the engine running the idle soeed may be wrong In this case the
122. ed in the EEPROM This test is also used as a security measure to pre vent improper use of calibrations or changes to these calibrations that may alter the designed function of EFI TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step checks to see if the fault is present dur ing diagnosis If present the ECM is not function ing correctly and must be replaced IMPORTANT At the time of printing vessels with fuel injection were not being field reprogrammed to correct this failure Replacement of the ECM with a factory reprogrammed ECM is necessary if Code 51 is current and resets when clearing codes is completed Index 56 112 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY DIAGNOSTIC AIDS An intermittent Code 51 may be caused by a bad cell in the EEPROM that is sensitive to temperature changes If Code 51 failed more than once but is in termittent replace ECM An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear c
123. ef Procedure 5C 159 Multi Port Components 5C 159 Flame Arrestor 5C 159 Throttle Body 5C 160 n 56 162 Intake Manifold 5C 164 Fuel Rail and Injectors 5C 166 Fuel Rail 5C 166 Pressure Regulator 5C 168 Fuel Injectors 5C 169 Throttle Body Injection and Multi Port Injection Sensor and Module Servicing 5C 170 Precautions 5C 170 Electronic Control Module ECM 5C 170 Knock Sensor KS Module 5C 171 Engine Coolant Temperature ECT SONGO MT 5C 172 Throttle Body Injection Components Manifold Absolute Pressure MAP Sensor 5C 173 Throttle Position TP Sensor 5C 173 Idle Air Control IAC Valve 5C 174 Knock Sensor 5C 175 Multi Port Injection Components Manifold Absolute Pressure MAP GONSO sc sack acute ko onan tea 5C 177 Throttle Position TP Sensor 5C 178 Intake Air Temperature IAT Sensor 5C 179 Idle Air Control IAC Valve 5C 180 Knock Sensor 5C 181 Knock Sensor KS Module 5C 182 Fuel Pump Relay 5C 184 Ignition Control IC System Components 5C 184 PrECOUHONS ax cxi su Rd x E Vet a ACER ees 5C 184 Ignition Coil 5C 185 opark Plug Replacement
124. eference CHECK ENGINE MECHANICAL FOR 1 Proper cylinder compression 2 Bentpushrods worn rocker arms broken valve springs worn camshaft lobes Repair or replace as necessary ADDITIONAL CHECKS A miss fire can be caused by Electromagnetic Interference EMI on the reference circuit EMI can usually be detected by monitoring engine RPM with a scan tool or a tachometer A sudden increase in RPM with little change in actual engine RPM change indicates EMI is present If the problem ex ists check routing of secondary wires check ground circuit Index 5C 128 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 ROUGH UNSTABLE OR INCORRECT IDLE STALLING Definition Engine runs unevenly or rough at idle also the idle may vary in RPM called hunt ing Either condition may be severe enough to cause stalling Engine idles at incorrect speed PRELIMINARY CHECKS Perform the important preliminary checks as described at the start of Troubleshooting Charts section CHECK FUEL SYSTEM FOR 1 Open in CKTs 467 or 468 2 Fuelinjector s leaking CHECK IGNITION SYSTEM FOR 1 Correct ignition timing 2 Possible opens in the following circuits CKTs 424 430 and 423 3 Possible short to ground in the following circuits CKTs 430 424 and 423 4 Faulty spark plugs wires etc Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION x AND THROTTLE BODY 5C 129 ROUGH UNSTA
125. eing field repro grammed to correct this failure Replacement of the ECM with a factory reprogrammed ECM is necessary if Code 51 is current and resets when clearing codes is completed Index 5C 98 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY DIAGNOSTIC AIDS An intermittent Code 51 may be caused by a bad cell in the EEPROM that is sensitive to temperature changes If Code 51 failed more than once but is in termittent replace ECM An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 51 Calibration Memory Failure Non Scan 2 of 2 e IGNITION ON e USING CLEAR CODE PROCEDURE CLEAR CODES DOES CODE 51 RESET YES NO REPLACE ECM AND VERIFY CODE DOES NOT RESET FAULT IS NOT PRESENT AT THIS TIME REFER TO DIAGNOSTIC AIDS ON FACING PAGE Index Bm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL E
126. either supply would cause the relay not to operate 3 This step ensures that a good ground exists to terminal 85 of the system relay An open ground to this terminal would not allow current to flow through the pull in coil 4 Atthis point the circuits leading to the relay have been checked and a careful visual inspection of the relay terminals should be preformed prior to replacement of the system relay 90 823224 2 796 EFI System Ignition Relay Check Continued 2 of 2 e IGNITION ON e USING A TEST LIGHT CONNECTED TO GROUND PROBE IGNITION COIL CONNECTOR TERMINAL B e LIGHT SHOULD BE ON IS IT YES REMOVE SYSTEM RELAY CONNECTOR SYSTEM CHECK CHART IGNITION WITH TEST LIGHT STILL CONNECTED TO GROUND PROBE RELAY CONNECTOR CAVITIES 86 AND 30 TEST LIGHT SHOULD LIGHT ON BOTH TERMINAL CAVITIES DID IT e CONNECT TEST LIGHT TO BATTERY POSITIVE B4 AND PROBE RELAY CONNECTOR CAVITY 85 REPAIR OPEN OR SHORT TO GROUND IN CIRCUIT e TEST LIGHT SHOULD LIGHT DID IT THAT DID NOT LIGHT e CHECK RELAY CONNECTOR FOR REPAIR OPEN OR GROUND POOR CONTACT OR CKT 150 AND RETEST CORROSION IF OK REPLACE SYSTEM RELAY Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x E AND THROTTLE BODY 5C 73 Ignition System Check 1 of 2 CONNECTOR IGN xi ein GRY CONNECTOR IGNITION CONNECTOR ACH TO DISTRIBUTOR O DISTRIBUTOR SYSTEM R
127. el pump electrical connectors Snap connector covers in place Secure electrical line in retainer clip Install L joint onto cover Tighten screw securely Connect all fuel lines to cover of vapor separator tank Torque fuel line fittings to 23 Ib ft 31 N m Connect fuel pump electrical connector With engine OFF cycle ignition switch to ON wait 2 seconds and then OFF four times waiting 10 seconds after each key off to prime the fuel sys tem and check for leaks NOTE If VST is ary remove the vent screw and fill with fuel 90 823224 2 796 Index Float and Needle Assembly REMOVAL 1 a Disconnect fuel pump electrical connector Elec tric fuel pump removed for visual clarity 72803 A VST equipped with elbow fitting on top of VST will have this configuration diaphragm and spring Electrical Connector Cover Lockwashers 6 Screws 6 Clip Valve Seat Float Valve Float Valve Pin Clip 10 Float 11 Float Arm Pin 12 Screw ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 143 2 Label and then disconnect all fuel lines from cov er of vapor separator tank 3 Remove electrical line from retaining clip some models 4 Hemove cover screws and remove cover and electrical line retainer clip 5 Remove float arm pin retaining fastener and re move float and needle assembly 6 Disassemble float and needle assembl
128. en ground CKT 814 MAP SENSOR 3656 3883V sv _ mens easy _ 7 000 8 000 2183 2488 2 8 4 3 V LOW ALTITUDE z HIGH PRESSURE z HIGH VOLTAGE 90 823224 2 796 Code 33 MAP Circuit Non Scan 2 of 2 Q e IGNITION OFF DISCONNECT VACUUM PLUG LOCATED UNDER PLENUM AT FRONT AND INSTALL A VACUUM GAUGE IN THE VACUUM PORT e START ENGINE AND RAISE RPM TO ABOUT 1000 RPM VACUUM GAUGE READING SHOULD BE 14in Hg 45 5 kPa OR MORE AND STEADY IS IT YES NO MEN 2 REPAIR LOW OR UNSTEADY IGNITION OFF VACUUM PROBLEM e REMOVE VACUUM GAUGE AND REINSTALL VACUUM PLUG IN VACUUM PORT e DISCONNECT MAP SENSOR ELECTRICAL CONNECTOR GNITION ON e CONNECT A DVM FROM HARNESS TERMINAL C 416 5 VOLT REFERENCE TO HARNESS TERMINAL A CKT 814 SENSOR GROUND IS VOLTAGE READING OVER 4 VOLTS CONNECT DVM FROM HARNESS TERMINAL C e CONNECT DVM FROM MAP SENSOR HARNESS CKT 416 TO HARNESS TERMINAL B MAP TERMINAL C TO A GOOD GROUND ON ENGINE SENSOR SIGNAL CKT 432 2 IS VOLTAGE READING OVER 4 VOLTS YES YES CONNECT DVM FAULTY CONNECTION AT ECM BETWEEN HARNESS OR TERMINAL B AND CKT 416 OPEN e IGNITION OFF e CONNECT A TEST LIGHT TO BATTERY POSITIVE B TOUCH TEST LIGHT TO HARNESS TERMINAL B MAP SENSOR SIGNAL IS TEST LIGHT ON FAULTY CONNECTION AT ECM OR ENGINE GROUND OR IS VOLTAGE OVER 4 SHORT
129. er or other contaminants on the contact mating surfaces 4 Incomplete mating of the connector halves dur ing initial assembly or during subsequent trouble shooting procedures 5 Tendency for connectors to come apart due to vibration and or temperature cycling 6 Terminals not fully seated in the connector body 7 Inadequate terminal crimps to the wire Wire harnesses should be replaced with proper part number harnesses When signal wires are spliced into a harness use the same gauge wire with high temperature insulation only With the low current and voltage levels found in the system it is important that the best possible bond be made at all wire splices by soldering the splices as shown in the following illustrations Use care when probing a connector or replacing connector termi nals It is possible to short between opposite termi nals If this happens certain components can be Index 5C 2 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY damaged Always use jumper wires with the corre sponding mating terminals between connectors for circuit checking NEVER probe through connector seals wire insulation secondary ignition wires boots nipples or covers Microscopic damage or holes will result in eventual water intrusion corrosion and or component or cir cuit failure WIRE REPAIR 1 Locate damaged wire 2 Remove insulation as required UB 73048 3 Splice two wires together using splice
130. erial INSTALLATION 1 Install fuel injectors and fuel meter body as pre viously described in this section 2 Install a new gasket on adapter plate 3 Install throttle body on adapter plate and torque the screws 30 ft Ib 40 N m 4 Connect throttle linkage to throttle body 5 Move throttle from idle to WOT and check that the throttle movement is not binding 6 Connect the fuel inlet and return lines Torque to 23 ft Ib 81 N m 7 Connect TP sensor IAC and fuel injectors con nections 8 Turn key to on position and check for fuel leaks around the inlet and return line connections 9 Start engine and check for fuel leaks Index 90 823224 2 796 Throttle Body Adapter Plate NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL IMPORTANT Place a clean shop towel over the intake manifold opening to prevent foreign mate rial from entering the engine 1 2 CONOR Q I ELECTRONIC FUEL INJECTION MULT Remove flame arrestor Remove throttle body refer to Throttle Body Sec tion Remove screws and the throttle body adapter from the intake manifold Screws 3 Throttle Body Unit Gasket Throttle Body Adapter Plate Gasket Intake Manifold Screws 2 Manifold Absolute Pressure MAP Sensor AND THROTTLE BODY 5C 153 Multi Port System Description The MerCruiser EFI Fuel System consists of a fuel supply
131. ex 5C 118 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 SURGES Definition Engine power variation under steady throttle or cruise Feels like the engine speeds up and slows down with no change in the throttle control PRELIMINARY CHECKS Perform the visual physical checks as described at the start of Troubleshooting Charts section CHECK FUEL SYSTEM FOR 1 Fuel pressure to be within specification while condition exists CHECK IGNITION SYSTEM FOR Condition of 4 terminal Ignition Control IC connector at distributor Connector wires must not be routed near spark plug wires Intermittent ground connection on ignition coil Proper operation advancing or retarding of Ignition Control IC Condition of distributor cap rotor and spark plug wires Proper and clean connection on distributor pick up coil terminal opark plugs that may be fuel fouled cracked worn improperly gapped burned electrodes or heavy deposits Repair or replace as necessary CHECK SENSORS AND CONTROLS FOR 1 Intermittent opens in Manifold Absolute Pressure MAP or Engine Coolant Temperature ECT sensor grounds CKT 814 If intermittent for a very brief period will not set DTC Intermittent short to grounds or opens in Manifold Absolute Pressure MAP sensor 5 volt refer ence CKT 416 and Manifold Absolute Pressure MAP sensor signal CKT 432 If intermittent for a very brief period will not set DTC Index
132. frequency The meaning of the frequency number can have any number of meanings to the computer An example of a pulse counter type of input is the dis tributor reference pulse input The computer can count a train of pulses a given number of pulses per engine revolution and determine the RPM of the en gine Engine Control Module ECM The Engine Control Module ECM is the control cen ter of the fuel injection system It constantly monitors information from various sensors and controls the systems that affect engine performance The ECM also performs a diagnostic function check of the system It can recognize operational problems and store a code or codes which identify the problem areas to aid the technician in making repairs 72801 Electronic Control Module ECM AND THROTTLE BODY 5C 11 ECM FUNCTION The ECM supplies 5 or 12 volts to power various sen sors or switches This is done through resistances in the ECM which are so high in value that a test light will not light when connected to the circuit In some cases even an ordinary shop voltmeter will not give an accurate reading because its resistance is too low Therefore the use of a 10 megohm input imped ance digital voltmeter is required to assure accu rate voltage readings MEMORY There are three types of memory storage within the ECM ROM RAM and EEPROM ROM Read Only Memory ROM is a permanent memory that is physically soldered to th
133. full engine power up to 2800 RPM but disables four fuel injectors above 2800 RPM until the engine RPM drops to 1200 RPM This feature allows the operator a comfortable ma neuvering speed while removing the possibility of high RPM engine operation until the problem is cor rected Index 5C 84 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY COOLANT OVERTEMP TO BUZZER LOW OIL PRESSURE 112 DK GRN LOW I O FLUID TO BUZZER 31 TAN TO LOW OIL PRESSURE GEAR LUBE SWITCHES AND TRANS TEMPERATURE MIE TEST DESCRIPTION NOTE Refer to Section 4C to test transmission tem perature switch 1 This step checks if wiring from the engine switches to the ECM is not shorted to ground 2 This step ensures that the discrete switches are functioning properly by changing state l O oil level transmission temperature will not change state DIAGNOSTIC AIDS e Check engine oil and I O fluid levels transmis sion fluid overheat e f above diagnostics are performed and no change in performance is made refer to Trou bleshooting An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion or a wire that is broken inside the insulation 90 823224 2 796 Discrete Input Circuit Check 2 of 2 OIL PRESSURE SWITCH DISCONNECT TAN BLU WIRE FROM OIL PRESSURE SWITCH START ENGINE THERE SHOULD BE RESISTANCE NO CONTINUITY FROM OIL PRESSURE SWITCH AND GRO
134. g Rough Un stable or Incorrect Idle in Troubleshooting 2 Low manifold vacuum may result from vacuum leaks in the engine induction system 3 This step checks for a voltage from terminal C 5 volt reference to terminal A sensor ground 4 This step will identify if the problem is in the sup ply 5 V reference or ground circuit 5 This step determines if the MAP signal circuit to the ECM is open 6 This step completes the test for the ECM and wir ing If the test light is not ON the MAP sensor has an internal problem To confirm an internal MAP sensor problem use the MAP output voltage check chart Index 5C 92 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 416 GRY 432 LT GRN 11 9 MAP SIGNAL 814 BLK GROUND DIAGNOSTIC AIDS An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared If Code 14 is also set check for op
135. g the speed at which the signal switches from one level to another Computers use voltage signals to communicate with one another The differ ent sections inside computers also use voltage sig nals to communicate with each other There are two kinds of voltage signals analog and digital Both of these are used in computer systems Its important to understand the difference between them and the different ways they are used Analog Signals An analog signal is continuously variable This means thatthe signal can be any voltage within a cer tain range An analog signal usually gives informa tion about a condition that changes continuously over a certain range For example in a marine engine temperature is usually provided by an analog signal There are two general types of sensors that produce analog signals the 3 wire and the 2 wire sensor Index 5C 10 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY THREE WIRE SENSORS MAP AND TP The following figure shows a schematic representa tion of a 3 wire sensor All 3 wire sensors have a ref erence voltage a ground and a variable wiper The lead coming off of the wiper will be the signal to the Engine Control Module ECM As this wiper position changes the signal voltage returned to the computer also changes ECM TYPICAL SENSOR VOLTAGE OUT SIGNAL INPUT 3 Wire Sensor TWO WIRE SENSORS ECT AND IAT The following figure is the schematic of a 2 wi
136. gnostic sys tem itself and should be addressed by consulting the appropriate diagnostic chart in Diagnostics Following the output of Code 12 the Malfunction Indi cator Lamp will indicate a diagnostic code three times if a code is present or it will simply continue to output Code 12 If more than one diagnostic code has been stored in the ECM s memory the codes will be output from the lowest to the highest with each code being displayed three times T AND THROTTLE BODY 5C 5 If a scan tool is used to read the codes follow the manufacturer s instructions SERVICE MODE When the diagnostic code tool is installed at the Data Link Connector DLC and the selector switch is set at SERVICE the system will enter what is called the SERVICE mode In this mode the ECM will 1 Display a Code 12 by flashing the Malfunction In dicator Lamp indicating the system is operating correctly 2 Display any stored codes by flashing the Mal function Indicator Lamp Each code will be flashed three times then Code 12 will be flashed again 3 The IAC valve moves to its fully extended posi tion blocking the idle air passage This is impor tant to remember as an attempt to run the vessel while in SERVICE mode will most likely result in an abnormally low idle speed or a stalled engine 4 Holds ignition advance steady NORMAL MODE Engines can be monitored in the normal mode Cer tain parameters can be observed without ch
137. he diagnostic chart Index 5C 66 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY WATER SEPARATING FUEL FILTER NOTE If pump does not run check fuel pump relay and fuse 1 Install the fuel pressure adapter in line at the throttle body 2 Wrapa shop towel around the fuel pressure con nector to absorb any small amount of fuel leak age that may occur when installing the gauge Ignition ON pump pressure should be 28 32 PSI 234 207 kPa This pressure is controlled by spring pressure within the regulator assembly Pressure that leaks down is caused by one of the following e Fuel pressure regulator valve leaking e sticking open e Check valve in fuel pump leaking 4 Aninjector that is stuck open will leak or drip fuel into the plenum of intake manifold which may saturate or foul spark plug s In order to deter mine which injector is leaking remove the flame arrestor and observe both fuel injectors with key on and engine off 90 823224 2 796 Throttle Body Injection Fuel System Diagnosis Continued Chart A 7 2 of 6 NOTE THE IGNITION MAY HAVE TO BE CYCLED MORE THAN ONCE TO OBTAIN MAXIMUM FROM PRESSURE ALSO IT IS NORMAL FOR THE PRESSURE HART A 3 TO DROP SLIGHTLY WHEN THE PUMP STOPS INSTALL FUEL PRESSURE GAUGE 91 16850 AND FUEL PRESSURE ADAPTER IGNITION OFF FOR 10 SECONDS IGNITION ON FUEL PUMP WILL RUN FOR ABOU
138. he battery being solidly connected Never separate the battery from the on board electrical system while the engine is running Never separate the battery feed wire from the charging system while the engine is running When charging the battery disconnect it from the boat s electrical system Ensure that all cable harnesses are connected solidly and that battery connections are thor oughly clean Never connect or disconnect the wiring harness at the ECM when the ignition is switched ON Before attempting any electric arc welding dis connect the battery leads and the ECM connec tor s When steam cleaning engines do not direct the steam cleaning nozzle at ECM system compo nents If this happens corrosion of the terminals or damage of components can take place Use only the test equipment specified in the diag nostic charts since other test equipment may ei ther give incorrect results or damage good com ponents All voltage measurements using a voltmeter re quire a digital voltmeter with a rating of 10 meg ohms input impedance When a test light is specified a low power test light must be used DO NOT use a high wattage test light While a particular brand of test light is not suggested a simple test as shown below on any test light will ensure it to be safe for system circuit testing Connect an accurate ammeter Index 90 823224 2 796 ELECTRONIC FUEL INJECTION ML such as the
139. he wiring harness 3 Manually adjust the engine throttle to 1800 RPM 200 4 If Not Using MerCruiser Timing Tool With en gine running set the scan tool or Diagnostic Code Tool to service mode 5 Shine the timing light at the timing mark indicator located on the timing chain cover NOTE If adjustment is needed loosen the distributor hold down bolt and rotate the distributor clockwise or counterclockwise to adjust the timing Then repeat the timing light check until the specification 8 de grees BTDC is met 6 Torque distributor hold down bolt to 30 Ib ft 40 N m 7 SetScan Tool or Diagnostic Code Tool to normal mode If using the MerCruiser Special Timing Tool disconnect it from DLC connector Index 5C 186 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 8 Manually close throttle to bring engine down to idle state Spark Plug Replacement SPARK PLUG WIRING AND BOOT PRECAUTIONS 1 Twist boots one half turn before removing 2 When removing boot DO NOT use pliers or other sharp tools which might tear the boot 3 DO NOT force any object between the wire and the boot or through the silicone jacket of the wiring 4 DO NOT pull on the wires to remove the boot Pull on the bootor useatool designed for this purpose 5 Special care must be used when installing spark plug boots to ensure that the metal ter minal within the boot is fully seated on the spark plug terminal and that the boot
140. ill offset the spring and result in a lower fuel pressure This idle vacuum will vary somewhat depending on barometric pressure however the fuel pressure at idle should be less indicating fuel pressure regulator control Pressure that leaks down is caused by one of the following e Fuel pressure regulator valve leaking e sticking open e Checkventline from VST to see if diaphragm is leaking If an injector is stuck open it will send fuel to its respective cylinder which may saturate or foul spark plug s In order to determine which injec tor is leaking the spark plugs must be removed and inspected for fouling or saturation Once the saturated spark plug s is found replace the cor responding injector s and install new spark plug s 90 823224 2 796 Multi Port Injection Fuel System Diagnosis Continued Chart A 7 2 of 6 CHART A 3 NOTE THE IGNITION MAY HAVE BE CYCLED ON MORE THAN ONCE TO OBTAIN MAXIMUM PRESSURE ALSO IT IS NORMAL FOR THE PRESSURE TO DROP SLIGHTLY WHEN THE PUMP STOPS INSTALL FUEL PRESSURE GAUGE 91 16850 IGNITION OFF FOR 10 SECONDS IGNITION FUEL PUMP WILL RUN FOR ABOUT 2 SECONDS NOTE FUEL PRESSURE WITH PUMP RUNNING SHOULD BE 34 38 PSI 234 262 kPa AND HOLD STEADY WHEN PUMP STOPS START AND IDLE ENGINE AT NORMAL OPERATING TEMPERATURE PRESSURE SHOULD BE LOWER c BY 3 10 PSI 21 69 kPa IGNITION OFF FOR SEE IGN
141. is step until all air is bled from gauge STEP 2 Turn ignition OFF for ten seconds and then ON again several times to get fuel pressure to its maximum Record this initial pressure reading Energize tester one time and note pressure drop at its lowest point Disregard any slight pressure increase after drop hits low point By subtracting this second pressure reading from the initial pressure we have the actual amount of injector pressure drop STEP 3 Repeat Step 2 on each injector and compare the amount of drop Usually good injectors will have virtually the same drop Retest any injector that has a pressure difference of 1 5 PSI 10 kPa either more or less than the average of the other injectors on the engine Replace any injector that also fails the retest If the pressure drop of all injectors is within 1 5 PSI 10 kPa of this average the injectors appear to be flowing properly Reconnect them and review Trou bleshooting NOTE The entire test should not be repeated more than once without running the engine to prevent flooding This includes any retest on faulty injectors 90 823224 2 796 Fuel Injector Balance Test Set up Multi Port Injection READING INITIAL PRESSURE FUEL PRESSURE GAGE INJECTOR CONNECTOR nd READING PRESSURE AFTER DROP EXAMPLE 1st 38 PSI 38 PSI 38 PSI 38 PSI 38 PSI 38 PSI 38 PSI 38 PSI Reading 262kPa 262kPa 262kPa 262kPa 262kPa 262kPa 262kP
142. jector b Fuel Filter c Seal Ring d Fuel Meter Body FUEL DAMPER The fuel damper acts as an equalization device to re duce the pressure spikes caused by the fuel injec tors 73766 Throttle Body Injection Shown a Fuel Damper Index 90 823224 2 796 ELECTRONIC FUEL INJECTION IDLE AIR CONTROL IAC VALVE The purpose of the IAC valve assembly is to control engine idle speed while preventing stalls due to changes in engine load The IAC valve mounted in the throttle body controls bypass air around the throttle valves 72800 IAC Valve Air Flow Diagram z amp AND THROTTLE BODY 5C 25 By moving a conical valve known as a pintle IN to ward the seat to decrease air flow or OUT away from the seat to increase air flow a controlled amount of air moves around the throttle valve If RPM is too low more air is bypassed around the throttle valve to increase it If RPM is too high less air is by passed around the throttle valve to decrease it The ECM moves the IAC valve in small steps called counts These can be measured by scan tool test equipment which plugs into the DLC During idle the proper position of the IAC valve is based on engine RPM If the RPM drops below speci fication and the throttle valve is closed the ECM senses a near stall condition and calculates a new valve position to prevent stalling e Engine idle speed is a function of total air flow into the engin
143. k 2 of 2 NOTE THIS CHART ASSUMES THE ENGINE CRANKS BUT WILL NOT START TURN IGNITION OFF TURN IGNITION AND CRANK ENGINE DOES ENGINE START wo ves LANYARD STOP CIRCUIT FUNCTIONING CHECK LANYARD STOP SWITCH TO MAKE SURE SWITCH IS IN ITS NORMAL POSITION GIG TO DIAGNOSTIC AIDS IS IT YES No IGNITION OFF DISCONNECT 2 WAY HARNESS CONNECTOR USING A DVOM MEASURE RESISTANCE BETWEEN PIN A CKT 942 AND PIN B GRD OF POSITION SWITCH CORRECTLY AND REPEAT STEP 1 OF 2 WAY CONNECTOR RESISTANCE SHOULD BE LESS THAN 5K OHMS IS IT RESISTANCE SHOULD BE INFINITE ON LANYARD STOP HARNESS SIDE IS IT 2 RESISTANCE LOWER ON BASIC HEI PROBLEM LANYARD STOP SWITCH REFER TO IGNITION SIDE OF CONNECTOR SYSTEM CHECK DISCONNECT ECM J 1 CHECK FOR FAULTY CONNECTOR LANYARD STOP SWITCH MEASURE RESISTANCE IF OK REPAIR SHORT TO BETWEEN PIN J1 21 OF GROUND IN CKT 942 ECM CONNECTOR AND AND RETEST GROUND RESISTANCE SHOULD BE INFINITE IS IT FAULTY ECM REPLACE ECM REPAIR SHORT TO GROUND AND RETEST LANYARD STOP IN CKT 942 BETWEEN ECM CIRCUIT J1 CONNECTOR AND LAN YARD STOP SWITCH Index Lm 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL x E AND THROTTLE BODY 5C 81 Audio Warning Buzzer Circuit Check 1 of 2 TO BUZZER TAN BLU TO IGN PUR TO AUDIO BL WARNING U 121 TAN PNK TO SYSTEM RELAY TERM SWITCHES TAN 87
144. king hardness proper routing and carbon tracking Wiring for proper connections pinches and cuts Moisture in distributor cap primary or secondary ignition circuit connections oalt corrosion on electrical connections and exposed throttle body linkages Ensure engine is in good mechanical condition Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULI 2S AND THROTTLE BODY 5C 115 INTERMITTENTS Definition Problem occurs randomly May or may not store a Diagnostic Trouble Code DTC DO NOT use the diagnostic trouble code charts for intermittent problems unless instructed to do so If a fault is intermittent incorrect use of diagnostic trouble code charts may result in replacement of good parts Most intermittent problems are caused by faulty electrical connections or wiring Perform careful check of suspected circuits for 1 Poor mating of the connector halves or terminals not fully seated in the connector body backed out or loose Improperly formed or damaged terminals and or connectors All connector terminals and con nectors in problem circuit should be carefully reformed or replaced to insure proper contact ten sion Poor terminal to wire connection crimping An intermittent may be caused by Electrical system interference caused by a sharp electrical surge Normally the problem will oc cur when the faulty component is operated Improper installation of electrical options such as lights
145. l fuel system condition If necessary perform fuel system diagnosis 2 Properly functioning fuel injectors CHECK IGNITION SYSTEM FOR 1 Opens and grounds in CKTs 423 424 and 430 Proper output voltage of ignition coil Cross fire between spark plugs distributor cap spark plug wires and proper routing of plug wires Faulty or corroded spark plug wires and boots Faulty spark plugs Power reduction mode activated 1996 Models and Older CHECK ENGINE FOR 1 Sticking or leaking valves 2 Proper valve timing broken or worn valve train parts Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT x I2 AND THROTTLE BODY 5C 131 BACKFIRE EXHAUST Definition Fuel ignites in the manifold making a loud popping noise PRELIMINARY CHECKS Perform the important preliminary checks as described at the start of Troubleshooting section CHECK FUEL SYSTEM FOR 1 An abnormal fuel system condition If necessary perform fuel system diagnosis 2 Proper functioning of fuel injectors CHECK IGNITION SYSTEM FOR Opens and grounds in CKTs 423 424 and 430 Properly functioning advancing and retarding of timing Ignition Control IC Proper output voltage of ignition coil Faulty or corroded spark plug wires and boots Faulty spark plugs CHECK ENGINE FOR 1 Possible sticking or leaking valves Index 5C 132 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 DIESELI
146. lay for two seconds When the ignition switch is turned to the crank posi tion the ECM turns the fuel pump relay ON causing the fuel pump to start If the ECM does not receive ignition reference pulses engine cranking or running it shuts Off the fuel pump relay causing the fuel pump to stop THROTTLE BODY UNIT The throttle body unit consists of three assemblies e Fuel meter cover and fuel damper e Fuel meter body and fuel injectors e Throttle Body Two Throttle Valves To Control Air Flow Into The Engine Idle Air Control IAC Valve Throttle Position Tp Sensor 73766 Throttle Body Idle Air Control IAC Valve Throttle Position TP Sensor Fuel Meter Cover Fuel Damper Fuel Meter Body Fuel Injector 2 oro O O O Index 5C 24 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 FUEL INJECTORS The injector assembly is a solenoid operated device controlled by the ECM that meters pressurized fuel to the intake manifold The ECM energizes the injec tor solenoid which opens a ball valve allowing fuel to flow past the ball valve and through a recessed flow director plate The director plate has six machined holes that control the fuel flow generating a conical spray pattern of finely atomized fuel at the injector tip Fuel is directed at the throttle causing it to become further atomized before entering the intake manifold 13773 Fuel In
147. le timing mode If this condition occurs while the engine is running the engine will simply operate in the ignition module timing mode Index 5C 20 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Open or Grounded REF HI Line This line provides the ECM with engine speed information If this line is open or grounded the ECM will not know that the en gine is cranking or running and will not run Open or Grounded REF LO Line This wire is grounded in the ignition module and provides a refer ence ground from the ignition module to the ECM The ECM compares reference ground with reference high voltage If this circuit is open or grounded at any other location than through the module it may cause poor performance Fuel Metering System General Description The function of the fuel metering system is to deliver the correct amount of fuel to the engine under all op erating conditions Multi Port Injection fuel is delivered to the engine by individual fuel injectors mounted in the intake manifold near each cylinder Throttle Body Injection fuel is delivered from two injectors mounted atop the intake manifold Modes of Operation The ECM looks at voltages from several sensors to determine how much fuel to give the engine The fuel is delivered under one of several conditions called modes All the modes are controlled by the ECM and are described below STARTING MODE When the ignition switch is turned to th
148. line shown in figure B is a replacement line per Ser vice Bulletin 93 26 If VST does not have style A or B refer to to this service bulletin 73797 90 823224 2 796 Cool Fuel System The Cool Fuel System consists of an electrical fuel pump water separating fuel filter and port mounted fuel cooler Fuel is drawn from the boat fuel tank through a water separating fuel filter by an electric fuel pump then through fuel cooler Fuel is fed to fuel injectors in the throttle body or fuel rail on multi port injection sys tem Excess fuel is routed back to water separating fuel filter from the pressure regulator mounted on the fuel cooler Index 90 823224 2 796 ELECTRONIC FUEL INJECTION FUEL FLOW DIAGRAM 74871 Throttle Body Injection System Typical a Vacuum Line To Flame Arrestor Throttle Body Injection Or Fuel Rail Multi Port Injection b Fuel Pressure Regulator c Fuel Cooler d Electric Fuel Pump e Water Separating Fuel Filter f Fuel From Tank g Direction Of Water Flow h Fuel Line To Fuel Pump i Fuel Line To Throttle Body Throttle Body Injection Or Fuel Rail Multi Port Injection j Excess Fuel Return To Water Separating Fuel Filter ey AND THROTTLE BODY 5C 23 Throttle Body Injection Components THROTTLE BODY UNIT EXPLODED VIEW FUEL PUMP ELECTRICAL COMPONENTS When the ignition switch is turned to the RUN posi tion the ECM will turn ON the fuel pump re
149. llows a Install four left bank fuel injectors into left bank of fuel rail b Install four right bank fuel injectors into right bank of intake manifold c Working from rear of engine to front insert the first rear left bank fuel injector into the in take manifold Next insert the first rear right bank fuel injector into the fuel rail Continue inserting fuel injectors into their respective bores working back and forth toward front of engine until all fuel injectors are in place b 72798 a Fuel Rail b Intake Manifold c Rear Right Bank Fuel Injector d Rear Left Bank Fuel Injector 2 Install fuel rail mounting bolts and torque to 105 Ib in 12 N m AND THROTTLE BODY 5C 167 3 Install new O rings on fuel inlet and outlet lines Lubricate O rings using a water soap solution and install lines to fuel rail Secure fuel line retain er to fuel rail using screw 72915 a Fuel Rail b Fuel Inlet Line c Fuel Outlet d O Rings e Fuel Line Retainer f Screw g Fuel Rail Retaining Screws 4 Connectelectrical connector at each fuel injector o Install plenum throttle body and flame arrestor as outlined in this section Pressure Regulator NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Remove flame arrestor throttle body plenum and fuel rail as outlined in this section Index 5C 168 ELECTRONIC FUEL INJECTION MULT
150. llustrated placement refer to Troubleshooting Scan Tool Normal Specifications Idle Warm Engine Closed Throttle Neutral ir 8 1 3 Volts or 45 55 kPa on 3 5 Volts Depends on Altitude and 2 w esum Dem 2 5 3 5 msec Depends on Water Air NOTE will read I O Level and MIE will read Trans Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION ey AND THROTTLE BODY 5C 49 CLEARING CODES USING DIAGNOSTIC CODE TOOL NON SCAN 1 Install diagnostic code tool Turn key ON Select service mode on code tool F To clear codes move the throttle while in neutral from 096 to 10096 then back to 0 Exit Service Mode on code tool Start engine and let run for fifteen seconds Turn key OFF for 5 seconds Select Service Mode on code tool ee N o0 Turn key ON and read codes If codes are still present check note following and repeat from otep 1 IGNITION OFF INSTALL MARINE DIAGNOSTIC CODE TOOL SWITCH TO NORMAL MODE IGNITION ON NOTE MALFUNCTION INDICATOR LAMP STEADY LAMP YES DID ENGINE START PRIOR TO DIAGNOSTIC CIRCUIT CHECK YES SWITCH CODE TOOL SERVICE MODE ARE ANY CODES OTHER THAN CODE 12 DISPLAYED DOES A CUSTOMER COMPLAINT OR DRIVEABILITY PROBLEM CURRENTLY EXIST YES NO REFER TO TROUBLE SHOOTING SECTION FAULT IS NOT PRESENT AT THIS TIME In
151. lti Port Injection Wiring Diagram Chart 4 Of4 5C 43 Throttle Body Injection Wiring Diagram Chart 1 4 5C 44 Throttle Body Injection Wiring Diagram Chart 2 4 5C 45 Throttle Body Injection Wiring Diagram Chart 3 Of4 5C 46 Throttle Body Injection Wiring Diagram Chart 4 Of4 5C 47 Diagnostic Circuit Check 5C 49 Scan Tool Normal Specifications Idle Warm Engine Closed Throttle Neutral 5C 49 No Malfunction Indicator Lamp Marine Diagnostic Code Tool Installed 56 52 DLC Data or Will Not Flash Code 12 Malfunction Indicator Lamp On Steady Marine Diagnostic Code Tool Installed Chart 2 1 of 2 56 54 Engine Cranks but Will Not Run Chart A 3 1 of 4 5C 56 Multi Port Injection Fuel System Diagnosis Chart 7 1 of6 5 60 Throttle Body Injection Fuel System Diagnosis Chart 7 1 of 6 5C 66 EFI System Ignition Relay Check 56 72 Ignition System Check 1 of 2 5C 74 Ignition System Check 2 of 2 5C 76 Idle Air Control IAC Functional Test rv 5C 78 Lanyard Stop Circuit Check Emergency Stop Circuit Check 1 of2 5C 80 Audio Warning Buzzer Circuit Check ior pm 5C 82 Discrete In
152. may affect engine operation Pull down switches are used in conjunction with the ECM to detect critical conditions to engine operation If a switch changes state from its normal at rest posi tion that is normally open to closed the ECM senses a change in voltage and responds by entering power reduction mode This engine protection feature allows the operator full engine power up to 2800 RPM but disables half of the fuel injectors above 2800 RPM until the engine RPM drops to 1200 RPMS This feature allows the operator a comfortable ma neuvering speed while removing the possibility of high RPM engine operation until the problem is cor rected Index 5C 16 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Switches which are used with the Fuel Injection sys tem to detect critical engine operation parameters are mM OilPressure Pressure LL Fluid Level on Stern Drive Transmission Temperature on MIE Models Engine Coolant Temperature IMPORTANT Models equipped with multiple en gines must use dual engine data link kit and com mon ground between engine blocks Otherwise there will be no serial data communication be tween engines and the power reduction mode will not control both engines e Triple three engine applications should connect the outboard engines e Quad four engine applications Should link the outer two outboard engines with one link and the two inboard engines with anothe
153. n electrical component DO NOT soak in any liquid cleaner or solvent as damage may result 1 Remove flame arrestor throttle body plenum and fuel rail as outlined in this section 2 Remove fuel injectors from fuel rail and intake manifold CLEANING AND INSPECTION Inspect fuel injectors for damage replace if neces sary INSTALLATION IMPORTANT When replacing injectors be cer tain to replace with the identical part and part number Other injectors may have the same ap pearance yet have a different part number and be calibrated for a different flow rate and if installed would cause performance difficulty or damage to the ECM Index 90 823224 2 796 ELECTRONIC FUEL INJECTION 1 O f Install new O rings on fuel injectors Lubricate O rings using a water soap solution 72799 Fuel Injector O Ring Install fuel injectors as outlined in Fuel Rail and Intake Manifold Install fuel rail plenum throttle body and flame arrestor as outlined in this section AND THROTTLE BODY 5C 169 Throttle Body Injection and BEMONSE Multi Port Injection Sensor 1 Disconnect J1 and J2 electrical connectors at en gine control module ECM and Module Servicing Precautions BEFORE attempting to disconnect and remove any module or sensor check to make sure that the engine ignition system is OFF Then discon nect the negative battery cable from the termi nal DO NOT reconnect th
154. nd then off four times waiting 10 se conds after each key off to prime the fuel system and check for leaks NOTE If VST is ary remove the vent screw and fill with fuel REMOVAL VST FUEL PUMP 1 2 9 Disconnect fuel pump electrical connector Label and then disconnect all lines from cover of vapor separator tank Remove electrical line from retaining clip Remove screw from L joint and pull L joint from cover Disconnect fuel pump electrical connectors as follows a Gently pry each side of connector cover up and over retaining tabs b Remove connector retaining nuts and re move connectors Remove cover screws and remove cover and electrical line retaining clip Carefully slide fuel pump assembly from cover Remove O ring plate adaptors and collar from fuel pump Remove screen from fuel pump 10 Remove plate and rubber cushion NOTE When replacing fuel pump make certain to replace with a fuel pump of the identical part number 90 823224 2 796 INSTALLATION 1 Install rubber cushion and plate making sure to align cutout in plate with pump inlet Install screen on fuel pump Install adaptors collar plate and new O ring on fuel pump Be sure that fuel pump relief valve fits through hole in plate Slide fuel pump into cover Apply Loctite Type 8831 to threads of cover screws Install cover and electrical line retainer clip and tighten cover screws securely Connect fu
155. ng ascrewdriver carefully pry up on fuel injec tor to remove it from the fuel meter body Use a screwdriver or rod under the the screwdriver when prying up Leave old gasket in place to pre vent damage to fuel meter body 73770 CLEANING AND INSPECTION Inspect fuel injectors for damage replace if necessary IMPORTANT When replacing injectors be cer tain to replace with the identical part and part number Other injectors may have the same ap pearance yet have a different part number and be calibrated for a different flow rate and if installed would cause performance difficulty or damage to the ECM 13772 a Part Indentification Number AND THROTTLE BODY 5C 151 INSTALLATION 1 Install new lower O rings on fuel injectors Lubri cate O rings using a water soap solution 73766 Fuel Injector b Upper O Ring c Lower O Ring d Fuel Filter 2 Install upper O rings in fuel meter body Lubricate O rings with water soap solution 3 Install fuel injectors into the fuel meter body Align the raised lug on the injector base with the notch in fuel meter cavity 73771 NOTE The electrical terminals of the injectors should be parallel with throttle shaft 4 nstall gasket and fuel meter cover torque screws to 28 in lb 3 0 N m and flame arrestor as outlined in this section Connect electrical connections to fuel injectors With engine OFF and ignition ON check for l
156. ng order to en sure correct diagnosis TEST DESCRIPTION Number s below refer to circled number s on the functional check chart 1 This step determines if the IAC valve is function ing properly 2 his step determines if the circuitry or the IAC valve is faulty Index 5C 78 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 32 28 IAC COIL A HIGH 22 13 IAC con LOW IAC COIL HIGH IAC COIL LOW DIAGNOSTIC AIDS Check for vacuum leaks unconnected or brittle vacu um hoses cuts etc Examine manifold and throttle body gaskets for proper seal Check for cracked in take manifold plenum Check open shorts or poor connections to IAC valve in CKTs 441 442 443 and 444 An open short or poor connection in CKTs 441 442 443 or 444 will result in improper idle control and may cause improper idle An IAC valve which is stopped and cannot respond to the ECM a throttle stop screw which has been tampered with or a damaged throttle body or linkage could cause improper idle 90 823224 2 796 Idle Air Control Functional Test 2 of 2 e START ENGINE ALLOW IDLE TO STABILIZE AND RECORD ENGINE RPM e PLACE ENGINE IN BASE TIMING OR SERVICE MODE DOES A NOTICEABLE DROP IN RPM OCCUR OR DOES ENGINE DIE SEE NOTE NOTE IN STEP 1A A 502 BLACKHAWK MAY NOT DIE BUT IDLE WILL DROP EXIT SERVICE MODE AND DRASTICALLY RESTART ENGINE ENGINE SPEED SHOULD GRADUALLY R
157. nk through a water separating fuel filter and fuel cooler by a electrical fuel pump A pressure regulator located on the fuel cooler main tains a constant fuel pressure The fuel bled off from the pressure regulator is delivered back to the water separating fuel filter The throttle body is the component of the system which supplies the air required for optimum fuel com bustion The throttle body consists of a housing two injectors two throttle plates throttle plate linkage idle air control IAC valve and throttle position TP sensor Service Precautions Always disconnect battery cables from battery BEFORE working on fuel system to prevent fire or explosion Be careful when cleaning flame arrestor and crankcase ventilation hoses gasoline is ex tremely flammable and highly explosive under certain conditions Be sure that ignition key is OFF DO NOT smoke or allow sources of spark or open flame in area when cleaning flame arrestor and crankcase ventilation hoses Be careful when changing fuel system compo nents gasoline is extremely flammable and high ly explosive under certain conditions Be sure that ignition key is OFF DO NOT smoke or allow sources of spark or open flame in the area while changing fuel filter s Wipe up any spilled fuel immediately Index 90 823224 2 796 ELECTRONIC FUEL INJECTION Be sure that the engine compartment is well ven tilated and that no gasoline vapors are present t
158. no light If light is ON repair short to voltage e f OK check the resistance of the injectors Should be 12 ohms 4 e Check injector harness connector Be sure terminals are not backed out of connector and contacting each other e If all OK replace ECM 90 823224 2 796 Engine Cranks but Will Not Run Continued Cha 2OF 4 rt A 3 4 of 4 FROM A 3 Q Q NO BLINKING LIGHT AT INJECTOR e IGNITION ON e PROBE INJECTOR HARNESS TERMINALS WITH A TEST LIGHT TO GROUND LIGHT SHOULD BE ON AT BOTH TERMINALS LIGHT BOTH RECONNECT INJECTOR S IGNITION OFF DISCONNECT ECM IGNITION ON PROBE TERMINALS J2 21 AND J2 5 WITH A TEST LIGHT TO GROUND STEADY LIGHT CHECK INJECTOR DRIVER CIRCUIT WITH TEST LIGHT FOR SHORT TO GROUND IF CIRCUIT IS NOT SHORTED CHECK RESISTANCE ACROSS EACH INJECTOR IN THE CIRCUIT RESISTANCE SHOULD BE 12 OHMS 4 OK NOT OK FAULTY ECM REPAIR SHORT TO GROUND OR REPLACE ANY INJECTOR THAT MEASURES UNDER 12 OHMS 4 OHMS LIGHT ON ONE LIGHT OFF BOTH DUE TO INJECTORS WIRED IN REPAIR OPEN IN INJECTOR PARALLEL THERE SHOULD BE A FEED CIRCUIT LIGHT ON BOTH TERMINALS IF NOT THE PROBLEM IS AN OPEN IN THE HARNESS TO THE TESTED INJECTOR LIGHT ON REFER TO FACING PAGE Index 90 823224 2 796 LIGHT OFF OPEN CKT 467 OR 468 ELECTRONIC FUEL INJECTION MUL zx AND THROTTLE BODY 5C 59
159. nostics are working correctly go to step 2 2 fthereis a code stored If a code is stored go di rectly to the numbered code chart in Diagnos tics This will determine if the fault is still present Scan Tool Use with Intermittents The scan tool allows manipulation of wiring har nesses or components with the engine not running while observing the scan tool readout The scan tool can be plugged in and observed while running the vessel under the condition when the Mal function Indicator Lamp turns ON momentarily or when the engine driveability is momentarily poor If the problem seems to be related to certain parame ters that can be checked on the scan tool they should be checked while running the vessel If there does not seem to be any correlation between the problem and any specific circuit the scan tool can be checked on each position watching for a period of time to see if there is any change in the readings that indicates intermittent operation The scan tool is also an easy way to compare the op erating parameters of a poorly operating engine with those of a known good one For example a sensor may shift in value but not set a trouble code Compar ing the senor s readings with those of the typical scan tool data readings may uncover the problem The scan tool has the ability to save time in diagnosis and prevent the replacement of good parts The key to using the scan tool successfully for diagnosis lies in the t
160. nt problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for INSTALL MARINE DIAGNOSTIC CODE TOOL CLEAR CODES REFER TO CLEARING CODES IDLE ENGINE FOR 1 MINUTE OR UNTIL MALFUNCTION INDICATOR LAMP COMES ON IGNITION ON ENGINE STOPPED e ENTER SERVICE MODE ON CODE TOOL AND NOTE CODES backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared IGNITION OFF DISCONNECT ECM CONNECTORS J1 AND J2 IGNITION ON DVOM SELECTOR SWITCH IN THE OHM RANGE PROBE ECM HARNESS CONNECTOR CKT 423 WITH AN OHMMETER TO GROUND IT SHOULD READ MORE THAN 3KQ OHMS Q DOES IT YES e PROBE ECM HARNESS CONNECTOR CKT 424 WITH A TEST LIGHT TO 12 VOLTS AND NOTE LIGHT LIGHT OFF e WITH OHMMETER STILL CONNECTED TO ECM HARNESS CKT 423 AND GROUND AGAIN PROBE ECM HARNESS CKT 424 WITH THE TEST LIGHT CONNECTED TO 12 VOLTS AS TEST LIGHT CONTACTS CKT 424 RESISTANCE SHOULD SWITCH FROM OVER TO UNDER 1KQ OHMS DOES IT e DISCONNECT DIS
161. num b Intake Manifold c Drain Line 3 Connect reference line to pressure regulator a b 72796 Reference Line Pressure Regulator VST Models Or Fuel Damper Cool Fuel Models 4 Connect IAT and MAP sensor electrical connec manifold and plenum tors 1 Carefully remove all gasket material from intake manifold and plenum Index pm 90 823224 2 796 ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 163 4 Z S q a AW iss aN AN ASI LL L ka RTT S SHY Sh AT 12195 a Intake Air Temperature IAT Sensor b Manifold Absolute Pressure MAP Sensor 5 Install throttle body and flame arrestor as outlined previously Intake Manifold NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Drain engine cooling system Refer to Section 6A Seawater Cooled Models 2 Remove flame arrestor throttle body and plenum as outlined previously Disconnect hoses from thermostat housing Disconnect intake manifold to circulating pump by pass hose from circulating pump 5 Disconnect all electrical leads necessary for in take manifold removal including fuel injector and distributor connections Carefully move wiring away from intake manifold 6 Disconnect crankcase ventilation hoses from rocker arm covers Remove distributor cap scribe a line on the distributor housing marking rotor p
162. o avoid the possibility of fire Make sure no fuel leaks exist before closing en gine hatch CAUTION Fuel pressure MUST BE relieved before servicing any component in the fuel system CAUTION DO NOT operate engine without cooling water being supplied to seawater pump or water pump impeller will be damaged and subsequent over heating damage to engine may result The following information MUST BE adhered to when working on the fuel system Always keep a dry chemical fire extinguisher at the work area Always install new O rings when assembling fuel system parts DO NOT replace fuel pipe with fuel hose Always relieve system fuel pressure prior to servicing any component in the fuel system DO NOT attempt any repair to the fuel system until instructions and illustrations relating to that repair are thoroughly understood Observe all Notes and Cautions SAND THROTTLE BODY 5C 147 Throttle Body Exploded Views Induction System Screws 3 Throttle Body Unit Gasket Throttle Body Adapter Plate Gasket Intake Manifold Screws 2 Manifold Absolute Pressure MAP Sensor Throttle Linkage Index 5C 148 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY O1 N 90 823224 2 796 Throttle Body 73766 1 Cap Screw 2 Cover Assembly 12 Throttle Body To Fuel Meter Body Gasket 3 Fuel Pressure Regulator 13 Throttle Body 4 Cover Assembly
163. o circled number s on the diagnostic chart 1 A Code 23 will set due to an open sensor wire or connection This step will determine if the wir ing and ECM are OK 2 Ifthe resistance is greater than 25 000 ohms re place the sensor Index 5C 90 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY IAT SENSOR SIGNAL 472 TAN 813 BLK SENSOR GROUND DIAGNOSTIC AIDS An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared If Code 21 is also set check CKT 813 for faulty wiring or connections Check terminals at sensor for good contact 90 823224 2 796 Code 23 Intake Air Temperature IAT Sensor Circuit Non Scan 1 of 2 Q e DISCONNECT IAT SENSOR IGNITION ON ENGINE STOPPED e CHECK VOLTAGE BETWEEN IAT SENSOR HARNESS TERMINALS USING A DIGITAL VOLTMETER 4 VOLTS OR OVER e CHECK RESISTANCE ACROSS IAT SENSOR TERMIN
164. ock sensor is faulty Index 5C 110 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY KNOCK SENSOR gt DIAGNOSTIC AIDS If CKT 496 is routed too close to secondary ignition wires the KS module may see the interference as a knock signal resulting in false retard An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 43 KS Circuit Scan 2 of 2 Q INSTALL SCAN TOOL e ENGINE IDLING COOLANT TEMP ABOVE 150 66 DOES SCAN TOOL INDICATE A FIXED VALUE GREATER THAN ZERO DEGREES OF KNOCK RETARD YES NO RECONNECT 5 WAY KS MODULE CONNECTOR CHECK FOR OPEN OR SHORT DISCONNECT KNOCK SENSOR HARNESS CONNECTOR IN CKT 496 CONNECT A TEST LIGHT TO BATTERY POSITIVE B START ENGINE HOLD ENGINE SPEED STEADY AT 2500 RPM RAPIDLY TOUCH TEST LIGHT TO KNOCK SENSOR HARNESS CONNECTOR TERMIN
165. odes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 51 Calibration Memory Failure Scan 2 of 2 e IGNITION ON e USING SCAN TOOL CLEAR CODES DOES CODE 51 RESET YES NO REPLACE ECM AND VERIFY CODE DOES NOT RESET FAULT IS NOT PRESENT AT THIS TIME REFER TO DIAGNOSTIC AIDS ON FACING PAGE Index Dmm 90 823224 2 796 ELECTRONIC FUEL INJECTION MULI x E AND THROTTLE BODY 5C 113 Troubleshooting Changes In Terminology Due to industry standardization of terminology for certain electronic engine controls some names and abbrevi ations have changed Uem CTS Coolant Temperature Sensor ECT Engine Coolant Temperature TPS Throttle Position Sensor TP Throttle Position MAT Manifold Air Temperature EST Electronic Spark Timing ALDL Assembly Line Data Link Diagnostic Trouble Codes ECT Engine Coolant Temperature TP Throttle Position Sensor IAT Intake Air Temperature MAP Manifold Absolute Pressure Important Preliminary Checks Before using this section you should verify the cus 2 Vacuum hoses for splits kinks and proper con tomer complaint and locate the correct symptom nections Check the items indicated under that symptom 3 Airleaks at throttle body plenum and intake man Several of the following symptom procedures call for ifold a careful visual physical check 4
166. odule timing mode If this condition occurs while the engine is running the engine will stop but it will restart and run in the ignition module timing mode with reduced power Grounded IC Line During cranking the IC voltage is at virtually zero so the ECM does not recognize a problem When engine RPM reaches the value for the run condition the ECM applies bypass voltage to the distributor module Bypass voltage on the module switches the distributor power transistor to the IC line Because the IC line is grounded it will have no voltage applied so it cannot operate the power tran sistor to enter the IC mode If the IC line becomes grounded while the engine is being operated the engine will stop and will be diffi cult to restart An open or ground in the IC or bypass will cause the engine to run on the distributor module timing This will cause reduced performance poor fuel economy and erratic idle Grounded or Open Bypass Line While the engine is cranking the IC line will be grounded and the ECM will not notice anything abnormal When run RPM is reached the ECM applies bypass voltage to the by pass line but because of the ground or open it will not be able to energize the relay Therefore the relay will stay de energized and the IC line will remain grounded When the ECM sees the IC line not toggling it will not enter the IC mode Since the relay is de energized the engine will continue to run in the ignition modu
167. ole to turn the oil pump drive shaft Re peat this adjustment as many times as needed until the distributor can be firmly seated and all components are in alignment 10 Install hold down clamp over distributor and bolt it securely to engine surface Torque bolt to 30 Ib ft 40 N m 11 Install distributor cap and secure in place with two Screws 12 Connect crankcase ventilation hoses to rocker arm covers 13 Install all electrical leads including fuel injector and distributor connections Refer to wiring dia grams 14 Connect intake manifold to circulating pump by pass hose 15 Connect hoses to thermostat housing 16 Install plenum throttle body and flame arrestor as outlined previously IMPORTANT Before proceeding to the following step be certain that engine will obtain an ade quate supply of water for cooling Refer to Sec tion 6A Seawater Cooled Models 17 Start engine Adjust ignition timing and check hose connections gaskets and seals for leaks 18 Inspect fuel line connections for fuel leaks Index 5C 166 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Fuel Rail and Injectors Fuel Rail NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Remove flame arrestor throttle body and ple num as outlined in this section 2 Disconnect electrical connector at each fuel in jector 3 Remove fuel line retainer
168. or NOTICE Refer to Service Precautions in Repair 3 Inspect seal for damage Procedures BEFORE proceeding INSTALLATION 1 Install MAP sensor to plenum using screws REMOVAL Torque screws to 44 62 Ib in 5 7 N m 1 Disconnect electrical connector at manifold ab solute pressure MAP sensor 72802 a Plenum 72802 b Manifold Absolute Pressure MAP Sensor a Plenum Screws b Manifold Absolute Pressure MAP Sensor C Screws 2 Connect electrical connector to MAP sensor d Seal 2 Remove screws from MAP sensor 3 Remove MAP sensor from plenum Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT zx AND THROTTLE BODY 5C 177 Throttle Position TP Sensor NOTICE Refer to Service Precautions in Repair We Procedures BEFORE proceeding REMOVAL 1 Remove flame arrestor throttle cable and throttle body as outlined in Throttle Body a b d amp 72800 2 a Throttle Body b Throttle Position TP Sensor 3 c Screws With Lockwashers d O Ring 2 Remove TP from throttle body CLEANING AND INSPECTION 1 e Clean the surfaces of the TP with a dry cloth Inspect the TP for signs of wear or damage Index 5C 178 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY INSTALLATION Install TP sensor to throttle body using screws with washers and Loctite 242 applied to threads Torque screws to 20 Ib in 2
169. ormation MUST BE adhered to when working on the fuel system Always keep a dry chemical fire extinguisher at the work area Always install new O rings when assembling fuel pipe fittings DO NOT replace fuel pipe with fuel hose DO NOT attempt any repair to the fuel system until instructions and illustrations relating to that repair are thoroughly understood Observe all Notes and Cautions 90 823224 2 796 Multi Port Exploded Views Flame Arrestor and Throttle Body 1 Cap Nut 9 O Ring 2 Flame Arrestor 10 Idle Air Control IAC Valve 3 Stud 11 Screw 4 Throttle Body 12 Mounting Bracket 1997 and Newer Models 5 Gasket 13 Screw 1997 and Newer Models 6 Throttle Position TP Sensor 14 Flame Arrestor 1997 and Newer Models 7 Washer 15 Screw 1997 and Newer Models 8 Screw n d ex 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT x ES AND THROTTLE BODY 5C 155 Plenum 72802 cO O N CN N N co N 95 O O NUN mamnmminm mu BN lt x gt 7A AN e VA I Eos N N SAY fh W 5C 156 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 0 Intake Air Temperature IAT Sensor O gt D gt z 5 9 z Z m 0 Ow o 1 ENT Ed co t 10 cO N 00 O THIS PAGE IS INTENTIONALLY BLANK n d ex mr 90 823224 2 796 ELECTRONIC FUEL INJECTION
170. osition Also mark position of distributor housing on intake manifold 9 Remove distributor housing hold down bolt and clamp Index 5C 164 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 10 Remove distributor from intake manifold IMPORTANT DO NOT crank engine over after distributor has been removed 11 Disconnect inlet fuel line at vapor separator tank VST and mechanical fuel pump and remove in let fuel line 12 Disconnect all miscellaneous items that will pre vent removal of manifold IMPORTANT It may be necessary to pry intake manifold away from cylinder heads and block in next step Use extreme care to prevent damage to sealing surfaces 13 Remove intake manifold bolts then remove in take manifold along with VST fuel rail and injec tors a Intake Manifold b Bolt Locations NOTE If intake manifold requires replacement transfer all remaining parts to new manifold 90 823224 2 796 CLEANING AND INSPECTION Apply a small amount of RTV Sealer on neoprene gasket ends 1 Clean gasket material from all mating surfaces IMPORTANT When cleaning cylinder head mat ing surface DO NOT allow gasket material to en ter engine crankcase or intake ports 2 Clean excessive scale and deposits from the wa ter passages 3 Inspect manifold for cracks or scratches Ma chined surfaces must be clean and free of all marks or deep scratches or leaks may result 4 Inspect intake pa
171. portant to understand that these Cautions and Notes are not exhaus tive because it is impossible to warn of all the possible hazardous consequences that might re sult from failure to follow these instructions Introduction The following manual has been prepared for effective diagnosis of the MerCruiser Electronic Fuel Injection system All information illustrations and specifications con tained in this manual are based on the latest product information available at the time of publication ap proval The right is reserved to make changes at any time without notice An understanding of the material contained herein and in subsequent publications issued when neces sary will assist service personnel in properly main taining the quality to which MerCruiser engine control systems are built Index 90 823224 2 796 weindex info ELECTRONIC FUEL INJECTION ML Visual Physical Inspection A careful visual and physical inspection must be performed as part of any diagnostic procedure This can often lead to fixing a problem without further steps Inspect all vacuum hoses for correct routing pinches cuts or disconnects Be sure to in spect hoses that are difficult to see Inspect all the wires in the engine compartment for proper connec tions burned or chafed spots pinched wires or con tact with sharp edges or hot exhaust manifolds This visual physical inspection is very important It must be done carefull
172. put Circuit Check Power Reduction Mode Non Scan waves UC PX UR REY 5C 84 Diagnostics Without Scan Tool 5C 86 Code 14 Engine Coolant Temperature ECT Sensor Circuit Non Scan 1 of 2 5C 86 Code 21 Throttle Position TP Sensor Circuit Non Scan 1 Of2 5C 88 Code 23 Intake Air Temperature IAT Sensor Circuit Non Scan 56 90 Code 33 Manifold Absolute Pressure MAP Sensor Circuit Non Scan 1 Of 2 5C 92 Code 42 Ignition Control IC Circuit Non Scan 1 of 2 56 94 90 823224 2 796 Page Code 43 Knock Sensor KS Non Scan 1of2 56 96 Code 51 Calibration Memory Failure Non Scan Diagnostics 1 of 2 5C 98 Diagnostics Using Scan Tool Scan 5C 100 Code 14 Engine Coolant Temperature ECT Sensor Circuit Scan 1 of 2 5C 100 Code 21 Throttle Position TP Sensor Circuit Scan 1 of 2 5C 102 Code 23 Intake Air Temperature IAT Sensor Circuit Scan 1 of 2 5C 104 Code 33 Manifold Absolute Pressure MAP Sensor Circuit Scan 1 of 2 5C 106 Code 42 Ignition Control IC Circuit Scan PE 5C 108 Code 43 Knock Sensor KS Scan 1 Of2 5C 110 Code 51 Calibration Memory Failure Scan 1 O 2 M 5C 112 Troubleshooting 5C 114 Changes In Terminology 5C
173. r ing normal operation At this time the timing can be adjusted by turning the distributor 90 823224 2 796 ECM PICK UP COIL MANIFOLD VACUUM IGNITION COIL TRIGGER SIGNAL COOLANT TEMPERATURE TRANSISTOR BASE MODULE Co RELAY ADVANCE B ic GROUNDED SUIS NO VOLTAGE APPLIED dc A REF HI SIGNAL BYPASS CONVERTER GROUND NL D REF LO Distributor Module Mode ECM PICK UP COIL MANIFOLD VACUUM IGNITION COIL TRIGGER SIGNAL Module e COOLANT TEMPERATURE Advance BATTERY RELAY o IC NOT GROUNDED REF HI g n pE g E gE p BYPASS VOLTAGE APPLIED GROUND D ECM Control Mode Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL E AND THROTTLE BODY 5C 19 Results of Incorrect Operation Open IC Line from the ECM to the Distributor Module While the engine is cranking the ECM ex pects to see the IC signal pulled to virtually zero be cause it is grounded in the distributor module Since the IC line is open it cannot be grounded by the mod ule and the IC signal will be able to rise and fall or do what is called toggling The ECM recognizes the tog gling as an abnormal condition and will not apply by pass voltage to the distributor module when the en gine reaches run RPM Since bypass voltage is not applied to the relay it re mains open and the engine continues to run on the pickup coil triggering in the ignition m
174. r link 90 823224 2 796 THIS PAGE IS INTENTIONALLY BLANK n d ex mr 90 823224 2 796 ELECTRONIC FUEL INJECTION sy AND THROTTLE BODY 5C 17 Spark Management High Energy Ignition with Ignition Control IC The Electronic Fuel Injection is controlled by an En gine Control Module ECM This module is the nerve decision center of the system It uses all the in formation it gathers to manage ignition spark deliver ing increased fuel economy and maximum engine performance The system uses inputs from sensors to make deci sions on the amount of spark advance or retard al lowed The system has been designed to control ignition ad vance and retard electronically by the ECM In order for the ECM to properly calculate spark ad vance it must always know at what speed the engine is running The engine speed signal is accomplished by a circuit within the distributor module which con verts the pickup coil voltage to a square wave refer ence signal that can be used by the ECM This square wave engine speed reference signal is known as REF HI The ECM must also have something to compare the REF HI value against Therefore an additional line is provided between the ECM and the distributor module that is known as REF LO These two lines between the ECM and the distributor pro vide a precise indication of engine speed The two other lines between the ECM and distributor which control the Ignition Control
175. ration Distributor Module Mode ECM Control Mode Base Ignition Timing Results of Incorrect Operation Fuel Metering System General Description Modes of Operation Fuel Metering System Components Multi Port Vapor Separator Tank VST Cool Fuel System Throttle Body Injection Components Multi Port Injection Components Throttle Body Assembly ECM Connector and Symptom Charts ECM Connector and EFI Symptoms Chart J 1 Circuits ECM Connector and EFI Symptoms Chart J 2 Circuits Multi Port Injector Balance Test Fuel Injector Balance Test Set up Multi Port Injection Index weindex info OO Page Wiring Harness Diagrams 5C 36 MCM 7 4LX MIE 7 4L Throttle Body Injection Bluewater Inboard 5C 36 MCM 7 4LX Multi Port Injection 454 502 Magnum Multi Port Injection MIE 454 Tournament Ski Multi Port Injection 502 Magnum Multi Port Injection 5C 38 Multi Port Injection Wiring Diagram Chart 1 4 5C 40 Multi Port Injection Wiring Diagram Ghart 2 a ss sss sia iawn 5C 41 Multi Port Injection Wiring Diagram Chart3Of4 5C 42 Mu
176. re type sensor This sensor is basically a variable resistor in series with a fixed known resistor within the comput er By knowing the values of the input voltage and the voltage drop across the known resistor the value of the variable resistor can be determined The variable resistors that are commonly used are called thermis tors A thermistor s resistance varies inversely with temperature ECM TYPICAL SENSOR SENSOR SIGNAL 5V SENSOR GROUND 2 Wire Sensor 90 823224 2 796 Digital Signals Digital signals are also variable but not continuously They can only be represented by distinct voltages within a range For example 1 V 2 V or 3 V would be allowed but 1 27 V or 2 65 V would not Digital sig nals are especially useful when the information can only refer to two conditions YES and NO ON and OFF or High and Low This would be called a digital binary signal A digital binary signal is limited to two voltage levels One level is a positive voltage the other is no voltage zero volts As you can see in the following figure a digital binary signal is a square wave mora Digital Binary Signal The computer uses digital signals in a code that con tains only ones and zeros The high voltage of the digital signal represents a one 1 and no voltage represents a zero 0 Each zero and each one is called a bit of information or just a bit Eight bits to gether
177. refer to Troubleshooting 2 If the ECM recognizes the low MAP signal the ECM and wiring are OK Index 5C 106 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 416 GRY 432 LT GRN 11 9 MAP SIGNAL 814 BLK MAP AND ECT GROUND DIAGNOSTIC AIDS If the idle is rough or unstable refer to Troubleshoot ing for items which can cause an unstable idle With the ignition ON and the engine OFF the man ifold pressure is equal to atmospheric pressure and the signal voltage will be high This information is used by the ECM as an indication of vessel altitude and is referred to as BARO Comparison of this BARO reading with a known good vessel with the same sensor is a good way to check accuracy of a suspect sensor Reading should be the same 4 volt An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code
178. rious systems Al though we will not cover them all in great detail there will be a brief description of each DISCRETE SWITCHES AUDIO WARNING KNOCK lt KNOCK MODULE SENSOR DIST PEV FOR IAT MULTI POR REF RPM TP MODELS ONLY Y ECM Y Y Y mec GNTION uc FUEL y DULE MOTOR INJECTORS FUEL AUDIO lt PUMP WARNING BUZZER SERIAL im DATA Index T 90 823224 2 796 ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 13 ENGINE COOLANT TEMPERATURE ECT SENSOR The Engine Coolant Temperature ECT Sensor is a thermistor a resistor which changes value based on temperature immersed in the engine coolant stream Low coolant temperature produces a high re sistance while high temperature causes low resis tance 4d a Engine Coolant Temperature ECT Sensor b Harness Connector C Locking Tab 73052 The ECM supplies a 5 volt signal to the ECT through a resistor in the ECM and measures the voltage The voltage will be high when the engine is cold and low when the engine is hot By measuring the voltage the ECM knows the engine coolant temperature Engine coolant temperature affects most systems the ECM controls A failure in the ECT circuit should set Code 14 Re member this code indicates a failure in the coolant temperature sensor circuit so proper use of the chart will lead to either repairing a wiring problem or replac ing the sensor INTAKE AIR TEMPERATURE IAT SE
179. rise steadily reach normal oper ating temperature and then stabilize when thermo stat opens See Intermittents in Troubleshooting An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 14 ECT Circuit Scan 2 of 2 Q IGNITION ON DOES SCAN TOOL DISPLAY A COOLANT TEMPERATURE VALUE GREATER THAN 266 130 C OR LESS THAN 22 F 30 C COOLANT TEMPERATURE SCAN DISPLAY GREATER THAN 266 130 C IGNITION OFF e DISCONNECT ENGINE COOLANT TEMPERATURE ECT SENSOR e IGNITION ON e SCAN TOOL SHOULD DISPLAY COOLANT TEMPERATURE BELOW 22 F 30 DOES IT CKT 410 SHORTED TO GROUND REPLACE ENGINE OR COOLANT FAULTY ECM TEMPERATURE SENSOR Index 90 823224 2 796 CODE 14 15 INTERMITTENT IF NO ADDITIONAL CODES WERE STORED REFER TO DIAGNOSTIC AIDS ON FACING PAGE COOLANT TE
180. rn line or a pressure regulator problem 90 823224 2 796 Multi Port Injection Fuel System Diagnosis Continued Chart A 7 4 of 6 NOTE THE IGNITION MAY HAVE TO BE CYCLED NTINUED FROM pm ON MORE THAN ONCE TO OBTAIN MAXI MUM PRESSURE HAS PRESSURE BUT LESS ABOVE 38 PSI 262 kPa THAN 34 PSI 234 kPa 3 e DISCONNECT FUEL RETURN LINE e FOLLOWING MANUFACTURER S INSTRUCTIONS ATTACH FLEX HOSE TO RETURN LINE INSERT THE OTHER END IN AN CHECK FOR RESTRICTED APPROVED GASOLINE CONTAINER NOTE FUEL PRESSURE FUEL LINES WITHIN 2 SECONDS AFTER IGNITION IS TURNED ON OK REPAIR FUEL LINE AND RECHECK CHECK FOR RESTRICTED FUEL LOCATE AND CORRECT RETURN LINE FROM FUEL RESTRICTED FUEL RETURN ABOVE 38 PSI 262 kPa 34 38 PSI 234 262 kPa e IGNITION OFF PRESSURE REGULATOR TO LINE TO VAPOR SEPARATOR POINT WHERE FUEL LINE WAS TANK e BLOCK FUEL RETURN LINE FOLLOWING DISCONNECTED INSTRUCTIONS CYCLE IGNITION ON PRESSURE SHOULD RISE ABOVE 38 PSI 262 kPa PENE REPLACE FOEL PRESSURE REGULATOR ABOVE 38 PSI HAS PRESSURE BUT LESS 262 kPa THAN 34 PSI 234 kPa FAULTY FAULTY PRESSURE REGULATOR FUEL PUMP Index 90 823224 2 796 ELECTRONIC FUEL INJECTION MUL E AND THROTTLE BODY 5C 63 Multi Port Injection Fuel System Diagnosis Continued Chart A 7 5 of 6 TO SYSTEM 902 RED 9 N e 339 PNK BLK d FUEL PUMP RELAY FUSE FUEL PUMP 465 D
181. rogrammable Read Only Memory High Energy Ignition Electromagnetic Interference Pressure Wide Open Throttle in hg Inches Of Mercury Index 90 823224 2 796 ELECTRONIC FUEL INJECTION ML T AND THROTTLE BODY 5C 3 Changes In Terminology Due to industry standardization of terminology for certain electronic engine controls some names and abbrevi ations have changed CTS Coolant Temperature Sensor ECT Engine Coolant Temperature TPS Throttle Position Sensor TP Throttle Position MAT Manifold Air Temperature IAT Intake Air Temperature EST Electronic Spark Timing IC Ignition Control ESC Electronic Spark Control KS Knock Sensor ALDL Assembly Line Data Link DLC Data Link Connector Diagnostic Trouble Codes Index 5C 4 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 ECM Self Diagnostics The ECM performs a continual self diagnosis on cer tain control functions This diagnostic capability is complemented by the diagnostic procedures con tained in this manual The ECM s language for com municating the source of a malfunction is a system of diagnostic codes The codes are two digit numbers that can range from 12 to 51 When a malfunction is detected by the ECM a code is set and the Malfunc tion Indicator Lamp is illuminated Diagnostic Code Tool With Malfunction Indicator Lamp There are various manufacturers of Diagnostic Code Tools Most Tool
182. s are equipped with a Malfunction In dicator Lamp MIL e It informs the service technician that a problem has occurred and that the vessel is in need of ser vice as soon as reasonably possible e It displays Codes stored by the ECM which help the technician diagnose system problems As a bulb and system check the lamp will come ON with the key on and the engine not running When the engine is started the light will turn OFF If the lamp remains ON the self diagnostic system has detected a problem If the problem goes away the light will go out in most cases after ten seconds but a code will remain stored in the ECM When the lamp remains ON while the engine is run ning or when a malfunction is suspected due to a driveability problem EFI Diagnostic Circuit Check must be performed These checks will expose mal functions which may not be detected if other diagnos tics are performed prematurely Intermittent Malfunction Indicator Lamp In the case of an intermittent problem the Malfunc tion Indicator Lamp will light for ten seconds and then will go out However the corresponding code will be stored in the memory of the ECM When unexpected codes appear during the code reading process one can assume that these codes were set by an intermit tent malfunction and could be helpful in diagnosing the system Index 90 823224 2 796 ELECTRONIC FUEL INJECTION ML An intermittent code may or may not reset IF IT IS
183. s may indicate a fail ure in the starting system circuit Index 5C 52 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 439 PNK BLK 916 YEL MASTER SLAVE 11 18 SERIALDATA 450 BLK WHT 31 14 ECM GROUND 450 BLKWHT 1 30 ECM GROUND 450 BLK WHT 461 ORN BLK DIAGNOSTIC TEST 451 WHT BLK TERMINAL MALFUNCTION IN DICATOR LAMP 1 11 IGNITION FEED 419 BRNAWHT 131 32 BATTERY FEED 1 16 BATTERY FEED DIAGNOSTIC AIDS Engine runs OK check e Faulty light bulb e CKT 419 open Engine cranks but will not run check e Continuous battery 50 amp circuit breaker open e Open EOM fuse e Battery circuit to ECM open e gnition circuit to ECM open e Poor connection to ECM e Faulty ECM ground circuit s Engine will not crank e Perform EFI system relay check 90 823224 2 796 No Malfunction Indicator Lamp Chart A 1 2 of 2 DOES THE ENGINE START YES IGNITION ON IS THE 10 AND 15 AMP ECM FUSE OK REMOVE MARINE DIAGNOSTIC CODE TOOL USING A TEST LIGHT CONNECTED TO GROUND PROBE TERMINAL F OF THE DLC CONNECTOR LIGHT SHOULD BE ON IS IT YES e CONNECT TEST LIGHT TO B BATTERY POSITIVE e PROBE DLC TERMINAL E e LIGHT SHOULD BE ON IS IT YES CONNECT TEST LIGHT BETWEEN DLC TERMINALS F AND E LIGHT SHOULD BE ON IS IT YES FAULTY DIAG REFER TO NOSTIC CODE DIAGNOSTIC TOOL AIDS O
184. s than the average drop of the other in jectors should be considered faulty and replaced In jector testers are available for various manufactur ers For 7 4L 454 and 502 engines the tester must be capable of selecting an injector pulse width in the range of 200 400 milliseconds m sec The recom mended starting point for these engines is approxi mately 300 m sec In any case a pulse width that drops the fuel rail pressure to half the normal operat ing pressure should be used STEP 1 Engine cool down period ten minutes is necessary to avoid irregular readings due to hot soak fuel boil ing Relieve fuel pressure in the fuel rail as outlined in Fuel Pressure Relief Procedure in Repair Proce dures Remove plenum as outlined in Repair Pro cedures With ignition OFF connect fuel pressure gauge to fuel pressure tap Disconnect harness connectors at all injectors and connect injector tester to one injector Use adaptor harness furnished with injector tester to energize in jectors Follow manufacturer s instructions for use of adaptor harness Ignition must be OFF at least ten seconds to complete ECM shutdown cycle Fuel pump should run about two seconds after ignition is turned ON Index 5C 34 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY At this point insert clear tubing attached to vent valve into a suitable container and bleed air from gauge and hose to ensure accurate gauge operation Re peat th
185. se as throttle is moved toward Wide Open Throttle WOT Throttle Position TP sensor 5 volt reference CKT 416 for open DTC 21 may be set Throttle Position TP sensor circuit for open or grounds DTC 21 may be set Manifold Absolute Pressure MAP output voltage check Coolant sensor out of specification Hi or low ADDITIONAL CHECKS 1 Proper alternator output voltage 2 Faulty or incorrect thermostat 3 Throttle linkage sticking binding or worn Index 5C 122 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 DETONATION SPARK KNOCK Definition A mild to severe ping usually worse under acceleration or heavy load The engine makes sharp metallic knocks that change with throttle opening PRELIMINARY CHECKS Perform the visual physical checks as described at the start of Troubleshooting Charts section CHECK FUEL SYSTEM FOR 1 Contaminated fuel 2 Poor fuel quality and proper octane rating 3 Fuel pressure within specification CHECK IGNITION SYSTEM FOR Proper ignition timing Proper operation of Knock Sensor KS system Ensure wires are routed AWAY from secondary or primary ignition wires Ignition system ground Proper heat range and gapped spark plugs Incorrect knock sensor or knock sensor module CHECK SENSORS AND CONTROLS FOR 1 Engine Coolant temperature ECT has shifted value 2 Binding or sticking Throttle Position TP sensor or salt corrosion Voltage
186. ship to shore radios sonar etc Improperly routed knock sensor wires Wires should be routed AWAY from spark plug wires igni tion and charging system components Secondary ignition shorted to ground Arching at spark plug wires spark plugs or open ignition coil ground coil mounting brackets Part of internal circuitry shorted to ground such as in starters relays and alternators If a visual physical check does not find the cause of the problem the EFI system can be tested with a voltmeter or a scan tool connected while observing the suspected circuit An abnormal reading when the problem occurs indicates the problem may be in that circuit Index 56 116 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 HARD START Definition Engine cranks OK but does not start for a long time Engine does eventually run or may start but immediately dies PRELIMINARY CHECKS Make sure proper starting procedure is being used See Owner s Manual Perform the careful visual ohysical checks as described at the start of Troubleshooting Charts section CHECK FUEL SYSTEM FOR Proper operation of fuel pump relay Relay will operate fuel pump for 2 seconds when ignition is turned ON Also look for open in CKT 465 fuel pump relay driver Clogged or dirty water separating fuel filter Contaminated fuel or winter grade fuel during warm weather Vapor lock condition or engine flooding Check fuel pressure
187. ssages for varnish buildup or other foreign material Clean as necessary INSTALLATION 72514 IMPORTANT When installing intake manifold Gaskets gaskets in the next step be sure to install gasket e co with marked side up Also both gaskets are NOT Gaskets identical Install gaskets on their respective 4 Setintake manifold gaskets in place aligning bolt sides of the engine DO NOT use ANY other gas Hales ket than that which is recommended 5 Carefully install intake manifold assembly and torque bolts to 25 Ib ft 34 N m in the sequence shown 1 Apply Quicksilver Perfect Seal to both sides of in take manifold gasket around coolant passages 72514 a Coolant Passages Be sure to read and follow package label direc tions when using bellows adhesive 2 Using Quicksilver Bellows Adhesive glue neo prene gaskets to engine block between cylinder heads 72916 Intake Manifold Torque Sequence Index Ix 90 823224 2 796 ELECTRONIC FUEL INJECTION MULT HE AND THROTTLE BODY 5C 165 6 Connectall miscellaneous items which were dis connected from manifold during removal 7 Connect inlet fuel line at vapor separator tank VST and mechanical fuel pump 8 Align rotor housing and intake manifold using scribe marks 9 Slowly lower distributor through intake manifold and into position If distributor shaft won t drop into position back it out and insert a screwdriver into the h
188. t the in take air temperature and coolant temperature values should read within a few degrees of each other An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter mittent complaint should be thoroughly checked for backed out terminals improper mating broken locks improperly formed or damaged terminals poor terminal to wiring connections corroded terminals and or wiring or physical damage to the wiring har ness After repairs clear codes following Clearing Codes in ECM Self Diagnostics Failure to do so may result in codes not properly being cleared 90 823224 2 796 Code 23 IAT Circuit Scan 2 of 2 e IGNITION ON e DOES SCAN TOOL DISPLAY IAT TEMPERATURE OF LESS THAN 22 F 30 C OR GREATER THAN 266 F 130 C YES TEMPERATURE LESS THAN 22 F 30 C Q IGNITION OFF DISCONNECT IAT SENSOR JUMPER HARNESS TERMINALS TOGETHER IGNITION ON SCAN TOOL SHOULD DISPLAY TEMPERATURE GREATER THAN 266 F 130 C DOES IT YES IGNITION OFF e JUMPER 472 TO ENGINE GROUND e IGNITION ON e SCAN TOOL SHOULD DISPLAY TEMPERATURE GREATER THAN 266 130 C DOES IT CODE 23 IS INTERMITTENT REFER TO DIAGNOSTIC AIDS ON FACING PAGE TEMPERATURE GREATER THAN 266 F 130 C 3 IGNITION
189. tage from the TP As the throttle valve angle is changed the voltage output of the TP also changes At a closed throttle position the voltage output of the TP is low approximately 5 volt As the throttle valve opens the output increases so that at wide open throttle W O T the output voltage should be near 4 5 volts By monitoring the output voltage from the TP the ECM can determine fuel delivery based on throttle valve angle driver demand A broken or loose TP can cause intermittent bursts of fuel from the injector and an unstable idle because the ECM thinks the throttle is moving 73049 ey AND THROTTLE BODY 5C 15 If the TP circuit is open the ECM will set a Code 21 If the TP circuit is shorted and a trouble Code 21 will be set A problem in any of the TP circuits will set a Code 21 Onceatrouble code is set the ECM will use a default value for TP DISTRIBUTOR REFERENCE DIST REF The distributor reference engine speed signal is supplied to the ECM by way of the Dist Ref Hi line from the High Energy lgnition HEI This pulse counter type input creates the timing signal for the pulsing of the fuel injectors as well as the Ignition Control IC functions This signal is used for a num ber of control and testing functions within the ECM DISCRETE SWITCH INPUTS POWER REDUCTION MODE 1996 AND OLDER MODELS Several discrete switch inputs are utilized by the sys tem to identify abnormal conditions that
190. ter can also be used to trigger the module by selecting ohms usually the diode position In this position the meter may have a voltage across its terminals which can be usedto trigger the module The volt age in the ohms position can be checked by using a second meter or by checking the manufactur er s specification of the tool being used Index PICK UP COIL C GBRE DISTRIBUTOR 4 TERMINAL CONNECTOR 423 WHT 430 PPLWWHT IGNITION CONTROL 12 8 DIST REFERENCE HIGH 424 TAN BLK 453 BLK RED 42 6 DIST REFERENCE LOW TO IN LINE HARNESS TACH 6 This should turn OFF the module and cause a spark If no spark occurs the fault is most likely in the ignition coil because most module prob lems would have been found before this point in the procedure 90 823224 2 796 Ignition System Check 2 of 2 N CHART CONTINUED FROM PAGE 75 LIGHT ON STEADY DISCONNECT DISTRIBUTOR 4 TERMINAL CONNECTOR REMOVE DISTRIBUTOR CAP DISCONNECT PICK UP COIL CONNECTOR FROM MODULE CONNECT VOLTMETER FROM TACH TERMINAL TO GROUND IGNITION ON INSULATE A TEST LIGHT PROBE TO 1 4 FROM TIP AND NOTE VOLTAGE AS TEST LIGHT IS MOMENTARILY CONNECTED FROM A VOLTAGE SOURCE 1 5 TO 8 V TO MODULE TERMINAL P CHART LIGHT BLINKS TEST LIGHT TO DC POWER SUPPLY 1 5 to 8 V REPLACE IGNITION COIL AND RECHECK FOR SPARK WITH TIMING LIGHT IF STILL NO SPARK REINSTALL ORIGI NAL COIL
191. the ECM drops and this signals the ECM to retard timing TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 This step ensures that the knock sensor circuitry is within the proper resistance value 2 Applying 12 volts with a test light to CKT 496 sim ulates a signal from the knock sensor The knock sensor is faulty if a response occurs 3 This step checks if a voltage signal from the KS module is present at the ECM 4 This step determines if ignition voltage is avail able to power up the KS module 5 This step confirms the ability of the KS module to remove the voltage from the signal line when it sees spark knock Since the knock sensor pro duces an AC voltage signal it may be necessary to repeatedly touch the harness connector with the test light probe to simulate this type of signal 6 This step checks the ground circuit from the KS module If the test light is dim check ground CKT 486 for excessive resistance Index 5C 96 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY DIAGNOSTIC AIDS If CKT 496 is routed too close to secondary ignition wires the KS module may see the interference as a knock signal resulting in false retard An intermittent problem may be caused by a poor or corroded connection rubbed through wire connec tion a wire that is broken inside the insulation or a corroded wire Any circuitry that is suspected as causing the inter
192. tor Reference Line to Plenum 5N Fuel Injector Check for contaminated fuel tank struck anti siphon 2 valve or vacuum leak anywhere before the mechani cal fuel pump Also possible slipping seawater fuel pump drive belt TEST DESCRIPTION Restricting the fuel return line Using Special Tool Shut Off Valve allows the fuel pressure to build above regulated pressure With battery voltage applied to the fuel pump pressure should rise to 60 PSI 414 kPa as the fuel return hose is gradu ally pinched Number s below refer to circled number s on the NOTE Do not allow fuel pressure to exceed 60 PSI diagnostic chart 414 kPa damage to the pressure regulator may re Sult 1 Pressure less than 34 PSI 234 kPa falls into two areas 3 This test determines if the high fuel pressure is e Regulated pressure less than 34 PSI 234 kPa The system will be running lean Also hard start ing when cold and overall poor performance will be noticed e Restricted flow causing pressure drop Normally an engine with a fuel pressure of less than 24 PSI 165 kPa at idle will not be driveable However if the pressure drop occurs only while underway the engine will surge then stop running as pres sure begins to drop rapidly This is most likely caused by a restricted fuel line or plugged water separating fuel filter Index 5C 62 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY due to a restricted fuel retu
193. uel pump circuit This step checks if there is an open in the ground circuit This step checks if the ECM is functioning proper ly Index 5C 70 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY FUEL PUMP 465 DK GRN WHT RELAY DRIVER 150 BLK l 90 823224 2 796 Throttle Body Injection Fuel System Diagnosis Continued Chart A 7 6 of 6 IGNITION OFF REMOVE FUEL PUMP RELAY IGNITION ON WITH TEST LIGHT CONNECTED TO GROUND PROBE FUEL PUMP RELAY CONNECTOR CAVITY 30 TEST LIGHT SHOULD BE ON IS IT YES IGNITION OFF USING FUSED JUMPER CONNECT TERMINALS 30 AND 87 OF FUEL PUMP RELAY CONNECTOR TOGETHER IGNITION ON FUEL PUMP SHOULD RUN DOES IT YES IGNITION OFF DISCONNECT FUSED JUMPER CONNECT TEST LIGHT TO BATTERY POSITIVE B AND PROBE CAVITY 86 OF THE FUEL PUMP RELAY CONNECTOR LIGHT SHOULD BE ON IS IT CONNECT TEST LIGHT TO GROUND AND PROBE CAVITY 85 OF THE FUEL PUMP RELAY CONNECTOR IGNITION ON TEST LIGHT SHOULD BE ON FOR 2 SECONDS AND THEN GO OFF DOES IT YES REPLACE FUEL PUMP RELAY AND RETEST IF STILL NO PRESSURE CHECK THE FOLLOWING VAPOR LOCK CONDITION RESTRICTED FUEL LINE DISCONNECTED HOSES PROPER FUEL LEVEL IF OK REPLACE FUEL PUMP Index 90 823224 2 796 e CHECK FUEL PUMP RELAY FUSE IS IT OK REPAIR OPEN CKT 339 OR 902 GROUN
194. ure Injector Harness Test Visually indicates injector electrical impulses from Light the ECM 1 82 A2 icksil Tool s peat 10 Displays problem codes stored in the ECM It also 84 822560A2 MERCRUISER Cable allows monitoring of various circuits and compo 91 822608 1 MERCRUISER Cartridge nents in the fuel injection system Displays problem codes stored in the ECM It also allows monitoring of various circuits and compo nents in the fuel injection system Allows for test fir ing injectors Diagnostic Code Tool 94008 Rinda Technologies Flashes light to display problem codes NOTE 1 The High Impedance Multimeter that comes with the existing Outboard EFI Tester 91 11001A1 meets the requirements listed above Gauge monitors manifold engine vacuum Hand pump used to check fuel pressure regulator EFI Scan Tool Injector 94040M Tester Rinda Technologies NOTE 2 Using a test light with 100 mA or less rating may show a faint glow when test actually states no light Kent Moore Tools Inc Rinda Technologies 29784 Little Mack 4563 N Elston Ave Roseville 48066 Chicago IL 60630 Phone 800 345 2233 Phone 312 736 6633 Index 5C 8 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Service Precautions The following requirements must be observed 1 Before removing any ECM system component disconnect the negative battery cable Never start the engine without t
195. valve a Throttle Body b Idle Air Control IAC Valve 3 Remove IAC from throttle body CLEANING AND INSPECTION 1 Remove and discard sealing O ring from IAC valve Clean sealing surfaces pintle valve seat and air passage with a carburetor cleaner to re move carbon deposits being careful not to push or pull on the IAC valve pintle Force exerted on the pintle might damage the worm drive DO NOT use a cleaner that contains the extremely strong solvent methyl ethyl ketone NOTE Shiny spots on the pintle or seat are normal and do not indicate misalignment or a bent pintle shaft 2 Inspect the entire assembly for any obvious physical damage 90 823224 2 796 INSTALLATION 4 Reset IAC valve pintle position after reconnect IMPORTANT If installing a new IAC valve be sure i D y CDI to replace it with the correct IAC valve pintle a Turn ignition key ON for ten seconds shape and diameter are designed for the specific b Turn ignition key OFF for ten seconds application c Restart engine and check for proper idle op 1 Install new O ring on IAC valve eration Knock Sensor NOTICE Refer to Service Precautions in Repair Procedures BEFORE proceeding REMOVAL 1 Disconnect electrical connector at Knock sensor located just ahead of starter motor 73766 a Throttle Body b Idle Air Control IAC Valve c O Ring d Screws 2 Install IAC valve in throttle body using
196. ve regulated leak anywhere before the electrical fuel pump pressure With battery voltage applied to the fuel and after the fuel pressure regulator pump pressure should rise to 60 PSI 414 kPa as the fuel return hose is shut off with special tool TEST DESCRIPTION NOTE Do not allow fuel pressure to exceed 60 PSI Number s below refer to circled number s on the 414 kPa damage to the pressure regulator may re diagnostic chart sult 1 Pressurelessthan 28 PSI 193 kPa falls into two 3 This test determines if the high fuel pressure is areas due to a restricted fuel return line or a pressure e Regulated pressure less than 28 PSI 193 kPa regulator problem The system will be running lean Also hard start ing when cold and overall poor performance will be noticed e Restricted flow causing pressure drop Normally an engine with a fuel pressure of less than 24 PSI 165 kPa at idle will not be driveable However if the pressure drop occurs only while underway the engine will surge then stop running as pres sure begins to drop rapidly This is most likely caused by a restricted fuel line or plugged water separating fuel filter Index 5C 68 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 90 823224 2 796 Throttle Body Injection Fuel System Diagnosis Continued Chart A 7 4 of 6 NOTE THE IGNITION MAY HAVE TO BE CYCLED NTINUED FROM pm ON MORE THAN ONCE TO OBTAIN MAXI MUM PRESSURE
197. voltage is supplied to the light bulb The Engine Control Module ECM will turn the lamp ON by grounding CKT 419 in the ECM With the diagnostic test terminal grounded CKT 419 the lamp should flash a Code 12 followed by any trouble code s stored in memory A steady light suggests a short to ground in the lamp control CKT 419 or an open in diagnostic CKT 451 Index 5C 54 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY 439 PNK BLK 916 YEL MASTER SLAVE 1 18 SERIAL DATA 450 BLK WHT 71 14 ECM GROUND 450 BLKWHT 1 30 GROUND 450 BLK WHT 4610RN BLK DIAGNOSTIC 451 WHT BLK TEST TERMINAL MALFUNCTION INDICATOR LAMP 41 11 IGNITION FEED 419 BRN WHT 131 32 BATTERY FEED 11 16 BATTERY FEED TEST DESCRIPTION Number s below refer to circled number s on the diagnostic chart 1 Ifthere is a problem with the ECM that causes a scan tool to not read serial data the ECM should not flash a Code 12 If Code 12 is flashing check CKT 451 for short to ground If Code 12 does flash make sure that the scan tool is working properly on another engine 2 Ifthe light goes OFF when the ECM connector is disconnected CKT 419 is not shorted to ground 3 This step will check for an open diagnostic CKT 451 4 At this point the Malfunction Indicator Lamp wiring is OK If Code 12 does not flash the ECM should be replaced 90 823224 2 796 No DLC
198. waiting 10 seconds after each key off to prime the fuel sys tem and check for leaks Index 90 823224 2 796 ELECTRONIC FUEL INJECTION AND THROTTLE BODY 5C 145 Throttle Body Injection Repair Procedures Electrical ignition and fuel system components on your MerCruiser are designed and manufac tured to comply with U S Coast Guard Rules and Regulations to minimize risks of fire and explo sion Use of replacement electrical ignition or fuel system components which do not comply with these rules and regulations could result in afire or explosion hazard and should be avoided Special Tools Part Number Fuel Pressure Gauge 91 168850A1 Lubricants Sealants Adhesives Part Number Loctite 8831 92 823089 1 Loctite 262 Loctite 242 Obtain Locally Index 5C 146 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Torque Specifications Fastener Location Lb In Flame Arrestor To Throttle Body Throttle Body To Adapter Adapter To Intake Manifold Heads Thermostat Housing Turns Maximum KnockSensor L TPSewo faf Distributor Hold Down 30 4 Clamp MAPSewo 5 6 11 90 823224 2 796 Throttle Body Injection System Description The fuel system consists of a fuel supply tank water separating fuel filter electric fuel pump pressure reg ulator fuel injectors throttle body and throttle posi tion TP sensor Fuel is drawn from the boats fuel supply ta
199. water separating fuel filter mechanical fuel pump vapor separator tank VST electric fuel pump injector fuel filter fuel rail pressure regulator fuel injectors throttle body and throttle position TP Sensor Sight Tube to Throttle Body Water Separating Fuel Filter Fuel Fill TS Taf Boat Fuel Tank Gen V Sea Fuel Pump Meedle amp Seat Assembly Prime Port d In Tank High Pressure Electric Fuel Pump Vapor Separating Tank Fuel Pressure Fuel Pressure Service Tap egulator Filter J im Fuel Pressure 50 a E ERIS EL SE E B Regulator pum l s Reference Line to Plenum Fuel is drawn from the boat s fuel supply tank through a water separating fuel filter by a mechanical fuel pump mounted on and driven by a seawater pump and is delivered to the vapor separator tank VST The VST consists of a reservoir float needle and seat assembly fuel pump pickup screen electric fuel pump The electric fuel pump located in the VST pumps the fuel rail supplying pressurized fuel to the fuel injectors A pressure regulator located on the fuel rail maintains a constant fuel pressure in the fuel rail The fuel bled off from the pressure regulator is delivered back to the VST The throttle body is the component of the system which supplies the air required for optimum fuel com bustion The throttle body consists of a housing
200. y i e float valve float valve pin clip and float CLEANING AND INSPECTION 1 Clean components with carburetor cleaner IMPORTANT Do not soak float or float valve in carburetor cleaner 2 Inspect float valve seat for wear Replace if nec essary 3 Inspect float and needle assembly i e float valve float valve pin clip and float Replace parts as necessary INSTALLATION 1 Assemble float and needle assembly i e float valve float valve pin clip and float NOTE Float is not adjustable 2 Install float and needle assembly and secure float arm pin using fastener 3 Apply Loctite 8831 to threads of cover screws Install cover and electrical line retainer clip and tighten cover screws securely 4 Secure electrical line in retainer clip 5 Connect all fuel lines to cover of vapor separator tank Torque fuel line fittings to 23 Ib ft 31 N m 6 Connect fuel pump electrical connector 7 With engine OFF cycle ignition switch to ON wait ing for 2 seconds and then OFF waiting 10 se conds after each key off four times to prime the fuel system and check for leaks NOTE IF VST is ary remove vent screw and fill with fuel Index 5C 144 ELECTRONIC FUEL INJECTION MULTI PORT AND THROTTLE BODY Diaphragm Assembly REMOVAL 1 Disconnect fuel pump electrical connector Elec tric fuel pump removed for visual clarity 72803 a A VST equipped with elbow fitting on top of VST will h
201. y and thoroughly Basic Knowledge and Tools Required To use this manual most effectively a general under standing of basic electrical circuits and circuit testing tools is required You should be familiar with wiring diagrams the meaning of volts ohms and amperes the basic theories of electricity and understand what happens in an open or shorted wire To perform sys tem diagnosis several special tools and equipment are required Please become acquainted with the tools and their use before attempting to diagnose the system Special tools which are required for system service are listed later in this section see Table of Contents Electrostatic Discharge Damage Electronic components used in control systems are often designed to carry very low voltage and are very susceptible to damage caused by electrostatic dis charge It is possible for less than 100 volts of static electricity to cause damage to some electronic com ponents By comparison it takes 4 000 volts for a person to even feel the effect of a static discharge There are several ways for a person to become stati cally charged The most common methods of charg ing are by friction and by induction An example of charging by friction is a person sliding across a seat in which a charge of as much as 25 000 volts can build up Charging by induction occurs when a per son with well insulated shoes stands near a highly charged object and momentarily touches ground Ch
202. y to the injectors and integrates the fuel pres sure regulator into the fuel metering system 72799 Fuel Rail b Pressure Regulator C Fuel Injector d Intake Manifold 90 823224 2 796 FUEL INJECTORS The EFl injector assembly is a solenoid operated de vice controlled by the ECM that meters pressurized fuelto a single engine cylinder The ECM grounds the injector solenoid which opens a pintle valve allow ing fuel to flow past the pintle valve The injector tip has holes that control the fuel flow generating a coni cal spray pattern of finely atomized fuel at the injector tip Fuel is directed at the intake valve causing it to become further atomized and vaporized before en tering the combustion chamber An injector that is stuck partly open will cause loss of pressure after engine shutdown This can result in long cranking times Dieseling can also occur be cause some fuel might be delivered to the engine af ter the ignition is turned OFF a Needle Valve b Nozzle c Cap d O Ring e Valve Stopper f Core g O Ring h Spring Housing j Solenoid Coil k Tape Bobbin m O Ring n Inner Collar o Sleeve p Terminal q Connector r Filter s O Ring Index 90 823224 2 796 ELECTRONIC FUEL INJECTION PRESSURE REGULATOR ASSEMBLY The pressure regulator is a diaphragm operated re lief valve with fuel pump pressure on one side and regul

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