Fuel Pump Electrical Circuit Diagnosis

CIRCUIT DESCRIPTION
When the key is turned ON, the powertrain control module (PCM) energizes the fuel pump relay which sends voltage to the lift pump. The lift pump remains ON during the glow plug cycle. If the engine is not started immediately after the glow plug cycle, the PCM shuts the fuel lift pump OFF and waits for the crank reference signal.

DIAGNOSTIC AIDS
Possible long crank times or a poor performance problem will exist.

TEST DESCRIPTION

Steps 1-9:

Steps 10-19:

The numbers below refer to step numbers on the diagnostic table.
2. Checks for proper operation of the fuel pump.
3. Checks the operation of the fuel pump by supplying 12 volts to the fuel pump control circuit.
4. Checks the battery feed circuit to the fuel pump relay.