Chart A1-7A Fuel System Diagnosis

Fuel System Diagnosis:

Fuel Pump Relay Circuit:

CIRCUIT DESCRIPTION
When the ignition switch is turned to the "ON" position, the Engine Control Module (ECM) will energize the fuel pump relay for 3 seconds, allowing for fuel pump operation. When the fuel pump relay is de-energized, the fuel pump stops operating. If the engine is being cranked, or is running, the fuel pump will continue to operate, as long as the ECM is receiving ignition reference pulses. If the ignition reference pulses are not detected, the fuel pump will stop after 3 seconds.

TEST DESCRIPTION
The numbers below refer to circled numbers on the diagnostic chart.

1. Checks fuel pump operation with ignition switch in the "ON" position.
2. Checks fuel pump relay switch for power.
3. Checks for faulty ECM or improper fuel pressure.
4. Checks fuel pump circuit.
5. Checks for an open PNK wire.
6. Checks fuel pump relay coil for power.
7. Checks for faulty fuel pump or an open BLK wire.
8. Checks for faulty fuel pump relay.
9. Checks for faulty ECM or an open PNK/WHT wire.

DIAGNOSTIC AIDS
Visual inspection of wiring and connectors should be made if an intermittent problem exists.