Fuel Pump Circuit Tests
- Check Fuel Pump Operation
- Ensure fuel pump operates for 2 seconds after turning ignition on. If fuel pump operates for 2 seconds, check fuel injector circuit. See FUEL INJECTOR CIRCUIT TESTS
. If fuel pump does not operate, go to next step.
- Check Fuel Pump Ground Circuit
- Turn ignition off. Disconnect fuel pump 6-pin connector. Ensure there is less than 5 ohms resistance between fuel pump connector terminal No. 5 (1.8L) or No. 4 (2.2L) and ground. See appropriate wiring diagram in WIRING DIAGRAMS
article. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open or short circuit in harness or connectors between fuel pump connector and chassis ground terminal as necessary.
- Check Fuel Pump Power Supply
- Turn ignition on. Ensure there is at least 10 volts between fuel pump 6-pin connector terminal No. 6 (1.8L) or No. 1 (2.2L) and ground. If voltage is less than 10 volts, go to next step. If voltage is 10 volts or more, replace fuel pump.
- Check Harness Resistance Between Fuel Pump & Fuel Pump Relay
- Turn ignition off. Ensure there is less than one ohm resistance between fuel pump 6-pin connector terminal No. 6 (1.8L) or No. 1 (2.2L) and fuel pump relay 4-pin connector terminal No. 4. If resistance is less than one ohm, go to next step. If resistance is more than one ohm, repair open or short circuit in harness between fuel pump and fuel pump relay or connectors as necessary. Check resistance between connector terminal No. 6 (1.8L) or No. 1 (2.2L) to ground. Resistance should be one Megohm minimum. If resistance is not as specified, repair short in harness between fuel pump and fuel pump relay connector.
- Check Fuel Pump Relay
- Disconnect fuel pump relay 4-pin connector and main relay 6-pin connector. Remove fuel pump relay and main relay with bracket. Connect battery voltage and ground to fuel pump relay terminals No. 1 and 3. Ensure there is less than 10 ohms resistance between terminals No. 2 and 4. If resistance is less than 10 ohms, go to next step. If resistance is greater than 10 ohms, replace fuel pump relay. See Fig 1
.
- Check Harness Resistance Between ECM & Fuel Pump Relay
- Turn ignition off. Disconnect ECM connectors. Ensure there is less than one ohm resistance between ECM connector terminal No. 32 and fuel pump relay 4-pin connector terminal No. 3. If more than one ohm is present, repair harness or connectors as necessary. If less than one ohms is present, inspect ECM connector terminal for poor contact. If ECM connector is okay, replace ECM.
Courtesy of SUBARU OF AMERICA, INC.