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Fuel Pump Circuit

CAUTION: After repair or replacement of malfunctioning parts, conduct Clear Memory Mode < Ref. to OPERATION , CLEAR MEMORY MODE> and INSPECTION MODE  < Ref. to OPERATION , INSPECTION MODE. >
DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK OPERATING SOUND OF FUEL PUMP. 
Make sure that fuel pump is in operation for two seconds when turning ignition switch to ON.
NOTE: Fuel pump operation can also be executed using Subaru Select Monitor (Function mode: FD01).
For the procedure, < Ref. to COMPULSORY VALVE OPERATION CHECK MODE . >
 Does fuel pump produce operating sound? Check fuel injector circuit. < Ref. to FUEL INJECTOR CIRCUIT , Diagnostics for Engine Starting Failure. > Go to step 2. 
2 CHECK GROUND CIRCUIT OF FUEL PUMP 
  1. Turn ignition switch to OFF.
  2. Remove fuel pump access hole lid located on the right rear of trunk compartment floor (Sedan) or luggage compartment floor (Wagon).
  3. Disconnect connector from fuel pump.
  4. Measure resistance of harness connector between fuel pump and chassis ground.

    Connector & terminal 

    (R58) No. 1 - Chassis ground: 

 Is the measured value less than 5 Ω? Go to step 3.  Repair harness and connector.
NOTE: In this case, repair the following:
  • Open circuit in harness between fuel pump connector and chassis grounding terminal
  • Poor contact in coupling connector
3 CHECK POWER SUPPLY TO FUEL PUMP. 
  1. Turn ignition switch to ON.
  2. Measure voltage of power supply circuit between fuel pump connector and chassis ground.

    Connector & terminal 

    (R58) No. 2 (+) - Chassis ground (-): 

 Is the measured value more than 10 V? Replace fuel pump. < Ref. to FUEL PUMP . > Go to step 4. 
4 CHECK HARNESS BETWEEN FUEL PUMP AND FUEL PUMP RELAY CONNECTOR. 
  1. Turn ignition switch to OFF.
  2. Measure resistance of harness connector between fuel pump and fuel pump relay.

    Connector & terminal 

    (R58) No. 2 - (B46) No. 4: 

 Is the measured value less than 1 Ω? Go to step 5.  Repair harness and connector.
NOTE: In this case, repair the following:
  • Open circuit in harness between fuel pump connector and chassis grounding terminal
  • Poor contact in coupling connectors
5 CHECK HARNESS BETWEEN FUEL PUMP AND FUEL PUMP RELAY CONNECTOR. 
Measure resistance of harness between fuel pump and fuel pump relay connector.
Connector & terminal 
(R58) No. 2 - Chassis ground: 		 Is the measured value more than 1 MΩ? Go to step 6.  Repair short circuit in harness between fuel pump and fuel pump relay connector.
6 CHECK FUEL PUMP RELAY. 
  1. Disconnect connectors from fuel pump relay and main relay.
  2. Remove fuel pump relay and main relay with bracket.
  3. Connect battery to fuel pump relay connector terminals No. 1 and No. 3.
  4. Measure resistance between connector terminals of fuel pump relay.

    Terminals No. 2 - No. 4: 

 Is the measured value less than 10 Ω? Go to step 7.  Replace fuel pump relay. < Ref. to FUEL PUMP RELAY . >
7 CHECK HARNESS BETWEEN ECM AND FUEL PUMP RELAY CONNECTOR. 
  1. Disconnect connectors from ECM.
  2. Measure resistance of harness between ECM and fuel pump relay connector.

    Connector & terminal 

    (B134) No. 11 - (B46) No. 3: 

 Is the measured value less than 1 Ω? Go to step 8.  Repair open circuit in harness between ECM and fuel pump relay connector.
8 CHECK POOR CONTACT. 
Check poor contact in ECM connector.		 Is there poor contact in ECM connector? Repair poor contact in ECM connector. Check fuel injector circuit. < Ref. to FUEL INJECTOR CIRCUIT , Diagnostics for Engine Starting Failure. >

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