Circuit Diagnosis - Fuel Pump Relay

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

When the ignition switch is turned ON, the PCM will activate the in-tank fuel pump. The fuel pump will remain ON as long as the PCM is receiving reference pulses from the distributor ignition system. If there are no reference pulses, the PCM will turn the fuel pump OFF after about 2-3 seconds. The pump will deliver fuel to the fuel rail and injectors, then to the pressure regulator, where the system pressure is controlled at 284-325 kPa (41-47 psi). Excess fuel is returned to the fuel tank. When the engine is stopped, the fuel pump can be turned ON with a scan tool.

^ Improper fuel system pressure will result in one or many of the following symptoms:

^ Cranks but will not run.

^ Cuts out, may feel like an ignition problem.

^ Poor fuel economy.

^ Loss of power.

^ Hesitation.

^ DTCs.

DIAGNOSTIC AIDS

The following conditions may have caused the fuel pump fuse to open:

^ The fuse was faulty

^ There is an intermittent short in the fuel pump power feed circuit.

^ The fuel pump has an intermittent internal problem. Refer to Symptoms.

TEST DESCRIPTION

Number(s) below refer to step numbers on the diagnostic table.

12. If the fuse is open, this circuit should be checked for a possible short to ground.