Fuel Pump Circuit

Wiring diagram: 

Engine Electrical System Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK OPERATING SOUND OF FUEL PUMP  .

   Check if the fuel pump operates for two seconds when turning the ignition switch to ON.

   NOTE: Fuel pump operation can be executed using the Subaru Select Monitor. Refer to "Active Test" for the procedures. Refer to ENGINE (DIAGNOSTICS) (H4DO)>ACTIVE TEST .

   Does the fuel pump emit operating sound?

   Yes  : Check the fuel injector circuit. Refer to ENGINE (DIAGNOSTICS) (H4DO)>DIAGNOSTICS WITH PHENOMENON>FUEL INJECTOR CIRCUIT .

   No  : Go to  2.

2. CHECK GROUND CIRCUIT OF FUEL PUMP (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from fuel pump.
   3. Measure the resistance of harness between fuel pump connector and chassis ground.

      Connector & terminal 

      (R132) No. 6 - Chassis ground:

   Is the resistance less than 5 Ω?

   Yes  : Go to  3.

   No  : Repair the following item.

   • Open circuit in harness between fuel pump connector and chassis ground
   • Poor contact of J/C
3. CHECK POWER SUPPLY TO FUEL PUMP  .
   1. Turn the ignition switch to ON.
   2. Measure the voltage between fuel pump connector and chassis ground.

      Connector & terminal 

      (R132) No. 5 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes  : Replace the fuel pump. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL PUMP ASSEMBLY .

   No  : Go to  4.

4. CHECK HARNESS BETWEEN FUEL PUMP AND FUEL PUMP RELAY (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Remove the fuel pump relay.
   3. Measure the resistance of harness between fuel pump connector and fuel pump relay connector.

      Connector & terminal 

      (R132) No. 5 - M/B (fuel pump relay) No. 3:

   Is the resistance less than 1 Ω?

   Yes  : Go to  5.

   No  : Repair the following item.

   • Open circuit in harness between fuel pump connector and fuel pump relay connector
   • Poor contact of coupling connector
5. CHECK HARNESS BETWEEN FUEL PUMP AND FUEL PUMP RELAY (SHORT TO GROUND)  .

   Measure the resistance between fuel pump connector and chassis ground.

   Connector & terminal 

   (R132) No. 5 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes  : Go to  6.

   No  : Repair the short circuit to ground in harness between fuel pump connector and fuel pump relay connector.

6. CHECK FUEL PUMP RELAY  .

   Check the fuel pump relay. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL PUMP RELAY .

   Is the check result OK?

   Yes  : Go to  7.

   No  : Replace the fuel pump relay. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL PUMP RELAY .

7. CHECK HARNESS BETWEEN ECM AND FUEL PUMP RELAY (OPEN)  .
   1. Disconnect the connector from ECM.
   2. Measure the resistance of harness between ECM connector and fuel pump relay connector.

      Connector & terminal 

      (B62) No. 31 - M/B (fuel pump relay) No. 4:

   Is the resistance less than 1 Ω?

   Yes  : Go to  8.

   No  : Repair the open circuit of harness between ECM connector and fuel pump relay connector.

8. CHECK POWER SUPPLY OF FUEL PUMP RELAY  .
   1. Turn the ignition switch to ON.
   2. Measure the voltage between fuel pump relay connector and chassis ground.

      Connector & terminal 

      M/B (fuel pump relay) No. 1 (+) - Chassis ground (-):

      M/B (fuel pump relay) No. 2 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes  : Repair the poor contact of ECM connector.

   No  : Repair the open or ground short in the harness of power supply circuit.

   NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Refer to ENGINE (Diagnostics) (H4DO)>Basic Diagnostic Procedure>PROCEDURE .