Fuel Pump Control

Fuel Pump Circuit:

Power to the fuel pump is controlled by the ECM through the control relay. See CONTROL RELAY.

Fuel Pump Test Connector Usage:

OPERATION TEST
To test the pump operation, connect a 12 Volt power source to the pump test connector (located on the firewall, near the battery). Remove the fuel cap and listen through the fuel filler neck for the sound of the pump. If the pump operates during the operational test, continue with the harness test. If no pump sound is heard, check the ground circuit (step #1) and also test the control relay see CONTROL RELAY. If no faults are found, replace the fuel pump.

HARNESS TEST
1. Disconnect the fuel pump connector located on the fuel tank. Using an Ohmmeter, check the ground circuit of the fuel pump between the harness connector terminal 2 and ground.

Continuity:
Should exist.

2. Using an Ohmmeter, check for continuity between the fuel pump check connector and the fuel pump harness connector terminal 1.

Continuity:
Should exist.

3. Disconnect the control relay connector. Using an Ohmmeter, check for continuity between the check connector and control relay harness connector terminal 2.

Continuity:
Should exist.

4. Disconnect the ECM connector. Using an Ohmmeter, check for continuity between the ECM harness connector terminal 8 and the control relay harness connector terminal 7.

Continuity:
Should exist.

5. Turn the key to the OFF position. Measure the supply voltage of the control relay from the battery. Using a voltmeter, measure the voltage between the control relay connector terminal 10 and ground.

Voltage:
System voltage.

6. Turn the key to the "ON" position. Measure the supply voltage of the control relay from the ignition switch. Using a voltmeter, measure the voltage between the control relay connector terminal 3 and ground.

Voltage:
8 or more volts.

7. Turn the key to the START position. Measure the supply voltage of the control relay from the ignition switch. Using a voltmeter, measure the voltage between the control relay connector terminal 9 and ground.

Voltage:
8 or more volts.

8. Using an Ohmmeter, check for continuity between the ECM harness connector terminal 8 and ground.

Continuity:
Should not exist.

9. Using an Ohmmeter, check for continuity of the ground circuit between the control relay harness connector terminal 6 and ground.

Continuity:
Should exist.

10. Using an Ohmmeter, check for continuity between the control relay terminal 2 and ground.

Continuity:
Should not exist.

11. Using an Ohmmeter, check for continuity between the fuel pump harness terminal 1 and ground.

Continuity:
Should not exist.

If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.
If the problem returns, it is possible that there is an intermittent failure of the component or the ECM. Check for looseness at all harness junctions and test for an intermittent failure. If the same trouble code reoccurs, the ECM will need to be changed.