FUEL SYSTEM Section 5B - MERCARB 2
Contents
1. c Pump Assembly 90 861329 1 MARCH 1999 Page 5B 22 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 13 Remove retainer clip and washer from pump shaft and lever assembly then remove accelerator pump assembly S gm 72409 a Pump Assembly b Retainer Clip c Lever Assembly FLOAT BOWL ASSEMBLY 1 Remove accelerator pump return spring from pump well Sedi Si Kee g ea A 72402 a Accelerator Pump Spring 2 Remove power valve assembly and gasket 72404 a Power Valve Assembly b Gasket Not Shown 90 861329 1 MARCH 1999 Page 5B 23 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 3 Remove main metering jets 12291 a Main Metering Jets b Gaskets Not Shown IMPORTANT Use care when removing venturi cluster to prevent damaging brass tubes which protrude from bottom of cluster DO NOT REMOVE TUBES These tubes are permanently pressed into the venturi cluster and are not replaceable 4 Remove three venturi cluster screws and carefully lift cluster and venturi gasket straight up 12292 a Venturi Cluster Brass Tubes b Gasket o Using needle nose pliers remove accelerator pump check ball spring retainer Turn float bowl over to remove spring and check ball 12407 a Spring Retainer b Spring and Check Ball Not Shown Page 5B 24 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR Cleaning and Inspection IMPORTANT DO NOT use a wire o2. 1 MARCH 1999 Page 5B 19 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 4 Remove air horn attaching screws as shown 72280 a Air Horn Attaching Screws 5 Carefully lift air horn from float bowl assembly r 4n a g al ZB y 72400 a Air Horn Assembly b Float Bowl Assembly 6 Invert air horn and carefully lay on bench 7 Remove float hinge pin and lift float assembly from air horn 72288 a Float Hinge Pin b Float Assembly Page 5B 20 90 861329 1 MARCH 1999 MERCARB 2 BARREL CARBURETOR C SERVICE MANUAL NUMBER 26 8 Check float weight as shown 12122 a Grams Scale b Float 9 Remove air horn gasket and baffle 72399 a Baffle b Air Horn Gasket 10 Remove needle assembly O A FeAl A DT Tre CON S m M 72287 Page 5B 21 C SRI 5 M CEU Lf YOO Q l a Needle Assembly b Needle Seat 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 CC MERCARB 2 BARREL CARBURETOR 11 Remove needle seat N AN p SS ae 72289 We rm mm S NI M Q a Needle Seat b Gasket c Screwdriver 72290 Needle and Seat Assemblies a Spring Loaded Type Needle Kit 3302 9029 b Solid Type Needle Kit 3302 9407 12 Loosen accelerator pump screw Slide pump shaft and lever assembly and washer out of air horn then remove accelerator pump assembly fs i GM S TO 72398 a Setscrew b Lever Assembly
3. S Quarts Liters All capacities are approximate fluid measures Carburetor Adjustment Specifications 9 16 14 See Note 1 3 32 27 See Note Accelerator Pump Discharge Hole Size 025 0 635 035 0 89 All measurements are 1 64 in 0 4 mm NOTE Float drop measured from air horn with gasket in place to toe of float Page 5B 4 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR High Altitude Re Jetting Engine flooding problems at idle rpm are generally related to the altitude above sea level at which they are operated If engine is running too rich at higher elevation order a smaller jet from the chart A jet stamped 165 is a 1 65 mm jet Carburetor 36 be 5000 9000 ft DE E Part Number od Below 1925 2745 m nd Above 3310 807504 JET SIZES Important Service Information Flooding at Idle RPM If your engine floods at idle rom check the following Problem in ignition system causing engine to run rough Idle mixture screw adjusted incorrectly Bad needle and seat ow S Incorrect float level drop 90 861329 1 MARCH 1999 Page 5B 5 MERCARB 2 BARREL CARBURETOR Needle Seat Change SERVICE MANUAL NUMBER 26 If the preceding steps failed to correct the problem change the needle seat to the other type MerCarbs are equipped with either the solid or the spring loaded needle 72290 Needle and Seat Assemblies a Spring Loaded Type Needle Kit 33
4. and should be replaced as a set only b Float Assembly and Hinge Pin Check float density to see if it is saturated with fuel by comparing weight of float with specifications If weight is high float assembly must be replaced Check hinge pin and holes for wear 90 861329 1 MARCH 1999 Page 5B 25 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 C Reassembly Fuel and Air Passages Passages must be perfectly clean for proper carburetor operation Accelerator Pump Plunger and Return Spring Inspect pump plunger cup pump plunger spring on pump assembly and return spring Power Piston Spring Check power piston spring for weakness or distortion Idle Mixture Needle Inspect idle mixture needle If damaged needle must be replaced Levers and Linkages Check levers links and rods for wear Throttle Valve and Shaft Check throttle shaft for excessive looseness in throttle body Check throttle valve and shaft for binding through entire operating range making sure valve opens and closes completely Throttle body assembly must be replaced if throttle valve and shaft are worn or damaged Choke Valve and Shaft and Lever Assembly Check shaft and lever assembly for excessive looseness in air horn assembly Check choke valve and shaft and lever assembly for binding through entire operating range making sure valve opens and closes completely Air horn assembly must be replaced if choke valve and shaft and lever assembly are
5. 02 9029 b Solid Type Needle Kit 3302 9407 Adjustable Accelerator Pump Lever This new 3 holed lever will allow you to change the amount of fuel delivered to the engine by the accelerator pump The hole closest to the lever s shaft will give the same amount of fuel as the single hole lever did The center hole gives approximately 0 5 cc less fuel and the hole farthest away will give about 1 0 cc less fuel 73131 a Full Accelerator Pump Stroke b 0 5 cc Less Fuel per Stroke c 1 0 cc Less Fuel per Stroke The technician should be able to correct most bogging problems with this 3 holed lever providing the bogging is caused by the carburetor When installing the 3 holed lever remove any metal ball that someone may have put in the accelerator pump well to limit pump travel Also make sure that the duration spring on the accelerator pump is stock and hasnt had several coils cut off Make sure the venturi cluster is the correct one as outlined previously under Specifications Page 5B 6 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR Description This MerCarb carburetor is a two bore carburetor and has a separate fuel feed for each venturi This model also is equipped with an electric choke A removable venturi cluster secured to float bowl assembly has the calibrated main well tubes and pump jets built into it The venturi cluster is serviced as a unit The serviceable main meterin
6. 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 4 Recheck BOTH float level and float drop 5 Carefully place air horn on float bowl making sure accelerator pump is correctly posi tioned in fuel well Lower air horn straight down to install 72400 a Air Horn Assembly b Float Bowl Assembly 6 Install seven short and one long air horn attaching screws Tighten screws evenly and securely 72280 a Air Horn Attaching Screws 7 Place end of choke rod in choke lever and collar assembly 12299 a Choke Rod b Choke Lever and Collar Assembly 90 861329 1 MARCH 1999 Page 5B 33 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 8 Place idle cam on choke rod 12392 a idle Cam b Choke Rod 9 Secure idle cam with choke rod installed on cam on float bowl assembly using screw Check that cam is free to move without binding 72282 a Screw b Idle Cam c Choke Rod 10 Place accelerator pump rod end with ear in hole in pump shaft and lever assembly 12393 a Accelerator Pump Rod b Pump Shaft and Lever Assembly Page 5B 34 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 11 Insert remaining end of accelerator pump rod into hole in throttle lever and secure with retainer clip 12283 a Accelerator Pump Rod b Throttle Lever c Retainer Clip CHOKE HOUSING ASSEMBLY 1 Install choke housing on air h
7. BURETOR IMPORTANT Boat must be in the water and engine at normal operating temperature to accurately check and adjust idle speed and mixture Carburetor should be set so that engine idles smoothly within range given under Specifica tions with boat in the water engine at normal operating temperature and drive unit in for ward gear To adjust idle speed and mixture proceed as follows IMPORTANT DO NOT attempt to compensate for other engine problems incorrect ignition timing faulty ignition components low compression vacuum leaks etc with carburetor adjustments This will only cover the problem which must be cor rected if engine is to achieve maximum fuel economy and performance 1 Connect an accurate shop tachometer to engine IMPORTANT DO NOT turn idle mixture needle tightly into seat as damage to needle and or seat may result 72281 a idle Mixture Needle 90 861329 1 MARCH 1999 Page 5B 13 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 2 f new or rebuilt carburetor has been installed turn idle mixture needle in clockwise until it lightly contacts seat then back out needle 1 1 4 turns This will provide a sufficient setting to allow starting engine 3 Start engine and run at 1500 rpm until engine reaches normal operating temperature DO NOT leave the helm unattended while performing idle speed and mixture adjust ments following BE CAREFUL NOT TO ACCIDENTALLY ACCELERATE ENGINE WHIL
8. E PERFORMING ADJUSTMENTS With boat in open water place remote control in forward gear idle position Disconnect throttle cable barrel from anchor stud Be sure not to lose spacer on anchor stud 6 Adjust idle speed adjustment screw to obtain 550 600 rpm in neutral gear With engine running at specified rpm adjust idle mixture needle as follows a Turn idle mixture needle in clockwise until the engine speed begins to drop due to lean mixture b Turn idle mixture screw out counterclockwise until the speed begins to drop due to rich mixture c Turn screw in to a point between these two extremes to obtain maximum engine smoothness and rpm d Readjust idle speed adjustment screw until engine idles at 650 700 rpm in forward gear IMPORTANT Refer to Section 2 Removal and Installation for throttle cable installa tion and adjustment Page 5B 14 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR Repair NOTICE Refer to Precautions in this section BEFORE proceeding Removal IMPORTANT Carburetor malfunctions are in many cases caused by the presence of dirt water or other foreign matter in carburetor To aid in diagnosis carefully remove carburetor from engine without draining fuel from bowl Contents of fuel bowl may then be inspected for contamination as carburetor is disassembled 1 Remove ventilation hose from flame arrestor then remove flame arrestor IMPORTANT Place
9. L NUMBER 26 Choke Inspection The choke does not require any periodic maintenance however if a choke malfunction is suspected the following should be done 1 With engine turned OFF remove flame arrestor 2 Open and close choke several times and check for binding loose or disconnected linkages or other signs of damage 3 f choke or linkage binds sticks or works sluggishly clean with carburetor choke cleaner Follow directions on can IMPORTANT Choke valve and shaft and lever assembly is not serviceable If valve and or shaft and lever assembly is worn or damaged air horn assembly must be replaced Adjustments NOTICE Refer to Precautions in this section BEFORE proceeding Pump Rod 1 Loosen idle speed screw until it no longer contacts idle cam 72284 a Idle Speed Screw b Idle Cam Page 5B 10 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 2 With throttle valves completely closed measure from flame arrestor mounting surface to top of pump rod 72682 a See Specifications 3 Carefully bend pump rod where shown to obtain specified dimension 72683 a Pump Rod b Bend Here 90 861329 1 MARCH 1999 Page 5B 11 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 Choke Setting Normal choke setting is such that scribed mark on cover is in line with long case mark on choke housing 12403 a Scribed Mark b More Choke c Less Choke If chok
10. SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR FUEL SYSTEM Section 5B MERCARB 2 BARREL CARBURETOR Table of Contents Identification 0 0 cc eee eee ee oB 2 Maintenance 0 000 e eae oB 8 Replacement Parts Warning oB 3 Flame Arrestor with Carburetor Cover 5B 8 Torque Specifications 5B 3 Fuel Inlet Filter oB 9 Io Aa m oB 3 Choke Inspection oB 10 Special Tools 00 0 eee oB 3 Adjustments 20 000 eee eee oB 10 Specifications 0 0 0 eee eee oB 4 PUMP SOUS scu a ip FERA REP ae Va CI ae oB 10 Carburetor Adjustment Specifications 5B 4 Choke Setting 05 5B 12 High Altitude Re Jetting oB 5 Preliminary Idle Speed and Mixture 5B 12 Important Service Information oB 5 Final Idle Speed and Mixture oB 13 Flooding at Idle RPM oB 5 seg Needle Seat Change 5B 6 Removal sssun Adjustable Accelerator Pump Lever 5B 6 Installation 0 0 0 0 ee eee Description 000 ce eee eee oB 7 Exploded View Parts List Precautions 0 0 cee eee eee oB 7 Disassembly Fuel Supply Connections oB 7 Cleaning and Inspection Reassembly 90 861329 1 MARCH 1999 Page 5B 1 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 Iden
11. a clean cloth in bores of carburetor to prevent dirt and foreign material from falling into bores Turn fuel supply off at fuel tank Disconnect throttle cable from carburetor Remove fuel line from fuel inlet nut using wrench to stabilize fuel inlet nut Remove fuel pump sight tube from carburetor Disconnect electric choke DU OD DE s Q9 gJ Remove carburetor attaching nuts and washers and remove carburetor IMPORTANT Place a clean cloth over intake manifold opening to prevent dirt or for eign material from entering manifold 8 Remove and discard gaskets Installation Thoroughly clean gasket surfaces 2 Place new carburetor base gasket on intake manifold Install carburetor and secure with nuts and washers Torque to 132 Ib in 15 Nm 3 If fuel inlet filter nut was disturbed remove clean all threads with brush and carburetor cleaner or Quicksilver Leveler 4 Connect fuel line to fuel inlet filter nut and while stabilizing filter nut with wrench tighten fuel line fitting securely Connect fuel pump sight tube to fitting on carburetor Connect electric choke wires to choke cover Install throttle cable as explained in SECTION 2 Install flame arrestor and crankcase ventilation hose Reconnect battery cables to battery O ee ds cr p 0 Ensure that water is supplied to cooling system Start engine and check for gasoline leaks If leaks exist STOP ENGINE IMMEDIATELY and recheck connections 11 Adjust
12. crewdriver IMPORTANT Float needle and needle seat are factory matched and tested and 12287 12399 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 6 Install float assembly and hinge pin Pivot float assembly up and down on hinge pin to ensure it moves freely 12297 a Float Assembly b Float Hinge Pin FLOAT LEVEL 1 Turn air horn upside down Pivot float assembly up and down on hinge pin to ensure it moves freely IMPORTANT Before checking float level raise float and allow it to fall however DO NOT force downward by hand 2 Measure float level using Universal Carburetor Gauge 91 36392 Measure from gas ket to toe of float 12298 12687 a Measurement With 2 Piece Solid Inlet Needle 3 8 in 10 mm b Measurement With Spring Loaded Inlet Needle 9 16 in 14 mm 90 861329 1 MARCH 1999 Page 5B 31 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 3 Bend float arm up or down at point shown to obtain specified dimension 72688 a Bend Float Arm at This Point 4 Visually check float alignment after adjustment FLOAT DROP 1 Hold air horn right side up to allow float to hang free 2 Measure float drop using Universal Carburetor Gauge 91 36392 Measure from gas ket to toe of float 72689 a Measurement 1 3 32 in 27 mm 3 Bend float assembly tang as shown to obtain specified dimension 72690 a Float Assembly Tang Page 5B 32
13. e adjustment is necessary 1 Loosen three choke cover retaining screws and adjust as shown 2 Tighten three choke cover retaining screws securely Preliminary Idle Speed and Mixture IMPORTANT The following adjustments will provide a sufficient idle speed and mix ture for starting engine Final adjustments must be made with engine running 1 Back out idle speed screw until it no longer contacts idle cam Turn idle speed screw in until it just contacts idle cam then turn screw in an additional two turns 72284 a Idle Speed Screw b Idle Cam IMPORTANT DO NOT turn idle mixture needle tightly against seat in the following step as damage to seat and or needle may result Page 5B 12 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 2 Turn idle mixture needle in until lightly seated then back needle out 1 1 4 turns 72281 a idle Mixture Needle Final Idle Speed and Mixture EMISSIONS CARBURETOR Sealed Carburetor Mixture Screw The carburetor on this engine has a seal on the carburetor mixture screw This seal prevents adjustment of the fuel mixture setting Do not remove mixture screw seal and or attempt to adjust fuel mixture setting Tampering with the mixture setting on this engine could affect the exhaust emissions level thus voiding the emissions certification This seal should only be removed by an authorized dealer or emissions testing agency NON EMISSIONS CAR
14. g jets are bleeds to properly meter the correct fuel air mixture to the engine Precautions f 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 hose gasoline is extremely 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 components gasoline is extremely flam mable and highly explosive under certain conditions Be sure that ignition key is OFF DO NOT smoke or allow sources of spark or flame in the area while changing fuel filter Wipe up any spilled fuel immediately Make sure no fuel leaks exist before closing engine hatch Fuel Supply Connections 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 overheat ing damage to engine may result 90 861329 1 MARCH 1999 Page 5B 7 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 Maintenance Flame Arrestor with Carburetor Cover NOTICE Refer to Precautions in this section BEFORE proceeding 1 Remove in the following order a Nut b Sealing washer c Crankcase ventilation hoses from flame arrestor and rocker arm covers d Flame ar
15. idle speed and idle mixture as outlined under Adjustments as previously out lined 90 861329 1 MARCH 1999 Page 5B 15 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 72686 Page 5B 16 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 Exploded View Parts List 1 Rod Accelerator Pump 2 Accelerator Pump Shaft and Lever Assembly 3 Washer Outer 4 Washer Inner 5 Screw 6 Washer 7 Screw 8 Spring 9 Filter 10 Gasket 11 Gasket 12 Nut Fuel Inlet 13 Choke Rod 14 Gasket 15 Clip Retainer 16 Washer 17 Pump Shaft and Lever Assembly 18 Accelerator Pump Assembly 19 Spring 20 Screw 21 Inlet Needle and Seat Spring Loaded Optional 22 Baffle Plate 23 Float 24 Float Bowl 25 Cam ldle 26 Screw 27 Idle Mixture Adjusting Needle 28 Spring 29 Washer 30 Nut 90 861329 1 MARCH 1999 MERCARB 2 BARREL CARBURETOR 31 Clip Pump Rod 32 Washer Locking 33 Nut 34 Throttle Lever 35 Spring 36 Screw Idle Speed Adjustment 37 Throttle Body 38 Screw 39 Washer 40 Gasket 41 Check Ball 42 Spring 43 Retainer 44 Screw 45 Lever Assembly 46 Screw 47 Choke Housing 48 Gasket 49 Air Horn 50 Inlet Needle And Seat 51 Pin 52 Screw 53 Gasket 54 Screw 55 Screw 56 Flat Washer 57 Lock Washer 58 Gasket 59 Venturi Cluster 60 Power Valve Assembly 61 Gasket 62 Gas
16. in pump well H ied S a 2 72402 a Accelerator Pump Spring Page 5B 28 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR AIR HORN ASSEMBLY IMPORTANT Accelerator pump assembly MUST BE installed correctly If pump assembly is installed incorrectly top of pump assembly will contact air horn casting 1 If accelerator pump assembly was removed from pump lever secure pump assembly to pump lever with washer and retainer clip as shown 72409 a Pump Assembly b Retainer Clip c Pump Lever 2 Insert pump shaft and lever assembly and washer into air horn then align indexed hole in pump lever with shaft and lever assembly and slide shaft all the way into lever so that shoulder on shaft is hitting lever Tighten setscrew securely tig RN t Ay 12398 a Setscrew b Lever Assembly c Pump Assembly 90 861329 1 MARCH 1999 Page 5B 29 SERVICE MANUAL NUMBER 26 Install needle seat and gasket Tighten securely MERCARB 2 BARREL CARBURETOR 3 Gi c mr RONY ACE c i gt SN 4 I WO N j f his a Needle Seat b Gasket should be replaced as a set only 4 Place needle assembly in needle seat S M E LLD S2 AN yy SE SN AS x Si re D a Needle Assembly b Needle Seat 5 Install baffle and gasket 9 MO SM S cU qo AM E 2 a Baffle b Gasket Page 5B 30 12289 c S
17. ket Page 5B 17 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 Disassembly The following is a step by step procedure for completely overhauling carburetor removed from engine In many cases however complete overhaul is not necessary and in these cases only the steps required to repair the carburetor malfunction should be performed Read the instructions carefully to prevent doing any unnecessary steps IMPORTANT Before performing any service on carburetor it is essential that carbu retor be placed in a holding fixture to prevent possible damage to throttle valves CHOKE HOUSING ASSEMBLY 1 Remove choke cover 72403 a Choke Cover 2 Remove choke lever Remove choke housing 72401 a Choke Lever b Choke Housing Page 5B 18 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR AIR HORN ASSEMBLY 1 Remove fuel inlet filter nut washers spring and filter as outlined previously 2 Remove accelerator pump rod retaining clip Pivot rod as required until retaining ear on rod and slot in pump shaft and lever assembly align allowing rod to be pulled out 12283 a Accelerator Pump Rod b Retainer Clip c Pump Shaft and Lever Assembly 3 Remove idle cam screw Also remove choke rod by pivoting rod as required until retaining ear on rod and slot in choke lever align allowing rod to be pulled out 12282 a idle Cam Screw b Idle Cam c Choke Rod 90 861329
18. orn tighten screws securely Install choke lever tighten screw securely IIT FID pr 4 72401 a Choke Housing b Choke Housing Attaching Screws c Choke Lever 2 Install choke cover Make sure hook on end of choke coil engages with choke lever Rotate choke cover until index marks align as shown Tighten screws securely 72403 a Scribed Mark b More Choke c Less Choke 90 861329 1 MARCH 1999 Page 5B 35
19. r drill to clean jet passages or tubes in carburetor as this may enlarge orifices and seriously affect carburetor calibration To avoid damage to carburetor DO NOT leave carburetor in immersion type carbure tor cleaner for more than two hours IMPORTANT DO NOT clean float bowl gasket surfaces with a gasket scraper or knife as sealing bead will be damaged and float bowl replacement will be necessary The float assembly float needle accelerator pump plunger and fuel filter MUST NOT BE immersed in carburetor cleaner as they will swell harden and or distort 72410 a Accelerator Pump Plunger b Float Needle c Fuel Filter d Float Assembly Avoid personal injury by always wearing safety goggles when using compressed air 1 Thoroughly clean all metal parts in a commercial carburetor cleaner until all deposits have been removed Follow cleaner manufacturer s instructions for proper cleaning and rinsing procedure Dry parts with compressed air 2 Using compressed air blow out all passages in carburetor to remove any foreign material Wipe off all parts that cannot be cleaned in carburetor cleaner with a clean dry cloth Carefully inspect all carburetor parts for wear and damage pay particular attention to the following a Float Needle and Seat If float needle or seat is worn or damaged replace with new needle and seat assembly IMPORTANT Float needle and seat are factory matched and tested
20. restor 2 Clean and inspect a Clean flame arrestor in solvent and blow dry with compressed air b Clean crankcase ventilation hoses c Inspect crankcase ventilation hoses for cracks or deterioration and replace if neces sary 3 Install in the following order a Flame arrestor b Crankcase ventilation hoses to flame arrestor and rocker arm covers c Sealing washer d Nut tighten securely 72086 a Nut b Sealing Washer c Crankcase Ventilation Hose d Flame Arrestor Page 5B 8 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR Fuel Inlet Filter NOTICE Refer to Precautions in this section BEFORE proceeding 1 Remove in the following order a Fuelline from fuel inlet filter nut b Fuelinlet filter nut and small gasket c Large gasket d Filter e Spring f omall gasket from inside filter nut 72406 a Fuel Line b Fuel Inlet Filter Nut c Gasket Large d Gasket Small e Filter f Spring 2 Clean filter nut and spring in solvent and dry with compressed air 3 Install in the following order Spring place in carburetor body Filter open end to inlet filter nut Small gasket place inside filter nut Large gasket place over filter nut threads Fuel inlet filter nut torque nut to 18 lb ft 24 Nm Fuel line torque to 18 Ib ft 24 Nm O29 20 5 90 861329 1 MARCH 1999 Page 5B 9 MERCARB 2 BARREL CARBURETOR SERVICE MANUA
21. tification 72680 Carburetor Part Number Location a Part Number b Date Code Data Code Explanation Example 2301 First Figure is Year 2 1992 3 1993 etc Second Figure is Month 2 February 3 March etc X October Y November Z December Third and Fourth Figures are Day of Month 01 First day 02 Second day etc 72779 Venturi Cluster Identification a Identification Number See Specifications b Accelerator Pump Discharge Holes Page 5B 2 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR Replacement Parts Warning Electrical ignition and fuel system components on your MerCruiser are designed and manufactured to comply with U S Coast Guard Rules and Regulations to mini mize risks of fire and explosion Use of replacement electrical ignition or fuel system components which do not comply with these rules and regulations could result in a fire or explosion hazard and should be avoided Torque Specifications Description Carburetor To Manifold Fuel Line to Carburetor Fuel Inlet Filter Nut Tools Universal Carburetor Gauge 91 36392 Special Tools Boroughs Special Tools Boroughs Special Tool and Equipment Inc 2429 N Burdick Street Kalamazoo MI 49007 616 345 5163 Float Gram Scale BT 8128 B 90 861329 1 MARCH 1999 Page 5B 3 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 Specifications NOTICE Unit Of Measurement U
22. worn or damaged Inspect Casting for visible damage Inspect gasket surfaces Inspect accelerator pump plunger well for scoring or deposits IMPORTANT DO NOT force idle mixture needle against seat as damage to needle and or seat will result FLOAT BOWL ASSEMBLY IMPORTANT Place float bowl and throttle assemblies in holding fixture to prevent throttle valves from being damaged 1 Install check ball spring and retainer in passage as shown Push retainer firmly into slots 72408 a Check Ball b Spring c Retainer Page 5B 26 90 861329 1 MARCH 1999 SERVICE MANUAL NUMBER 26 MERCARB 2 BARREL CARBURETOR 2 Install new gasket on venturi cluster as shown 72296 a Venturi Cluster I D No 421 b Gasket 3 Install venturi cluster in carburetor as shown 72397 a Venturi Cluster b Gasket 4 Install flat washer and new fiber washer on center screw Lockwashers and flat washers are used on outer screws Tighten screws evenly and securely TO CG On qmm T C33 72405 a Center Screw b Outside Screws c Fiber Washer 90 861329 1 MARCH 1999 Page 5B 27 MERCARB 2 BARREL CARBURETOR SERVICE MANUAL NUMBER 26 o Install main metering jets with gaskets as shown Tighten securely 72291 a Main Metering Jets b Gaskets Not Shown 6 Install power valve with new gasket Tighten securely 72404 a Power Valve b Gasket Not Shown 7 Place accelerator pump spring
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