BMW 3 Series Service Manual
Contents
1. FUEL TANK AND FUEL PUMP 160 7 Fig 9 Fuel pump relay terminal identification Fuel Pump Electrical Tests Troubleshooting of any fuel pump fault should begin with checking the fuel pump fuse and the fuel pump relay The DME main relay should also be checked NOTE Special tools are required for some of the tests de scribed here Fuel pump electrical circuit testing The fuel pump electrical circuit diagram is shown in Fig 10 CAUTION Fuse and relay locations may vary Use care when troubleshooting the electrical system at the fuse relay panel To resolve problems in identify ing a relay see an authorized BMW dealer 1 Remove rear seat cushion pull right side insulation mat back to expose fuel tank access cover Remove cover to expose wiring connections 2 Remove fuel pump relay and operate fuel pump as de scribed under Operating fuel pump for tests earlier Pump should run Disconnect jumper wire when fin ished 3 If fuel pump does not run disconnect black harness connector from tank sender unit With jumper wire con nected as described in step 2 above check for positive battery voltage at harness connector terminals See Fig 11 From Main Relay 15 power with key in run From B junction point or start position battery voltage at all times Js RD WT J 1 5 RD Fuel Pump Relay Ee 5 GN VI From Engine ee GN VI Control Module Fuse 18 15 amp Front P2. ower I Distribution Box apres lar 16 25 GNNI m ga Fuel Pump in tank af Ground below center console WIRING COLOR CODE 0011946 Fig 10 Fuel pump electrical circuit 4 If voltage and ground are present fuel pump is proba bly faulty If there is no voltage check wiring from fuel pump relay and make sure relay is functioning correctly Fuel pump power consumption testing NOTE e To achieve accurate test results the battery voltage at the connector should be approximately 13 volts Charge the battery as necessary A higher than normal power consumption usually in dicates a worn fuel pump which may cause intermit tent fuel starvation due to pump overheating and seizure The only remedy is pump replacement Be sure to check that the return line and the pump pickup are not obstructed before replacing the pump 1 Remove rear seat cushion pull right side insulation mat back to expose fuel tank access cover Remove cover to expose wiring connections 2 Disconnect black harness connector from fuel pump 3 Connect an ammeter and an insulated jumper wire be tween terminals in connector and corresponding pump terminals See Fig 12 FUEL PUMP
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