Chart A-5 Fuel System Electrical Test

Diagnostic Chart A-5, Fuel System Electrical Check:

Fuel System Circuit:

CIRCUIT DESCRIPTION
When the ignition switch is turned "ON," the Powertrain Control Module (PCM) energizes the fuel pump relay which completes the circuit to the in-tank fuel pump. It will remain "ON" as long as the engine is cranking or running and the PCM is receiving fuel control pulses. If there are no fuel control pulses, the PCM de-energizes the fuel pump relay within 2 seconds after key "ON" or the engine is stopped.

The fuel pump delivers fuel to the fuel rail and injectors, then to the pressure regulator, where system pressure is controlled. Excess fuel is bypassed back to the fuel tank. When the engine is stopped, the pump can be turned "ON" by applying battery voltage to the fuel pump test connector in the engine compartment using a fused jumper.

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks the fuel pump relays ignition feed CKT 839 and ground CKT 451.
2. This step determines if the fuel pump circuit is being controlled by the PCM. The PCM should energize the fuel pump relay and turn the fuel pump ON." If the engine is not cranking or running, the PCM should de-energize the relay and/or fuel pump within 2 seconds after the ignition is turned "ON."
3. This test checks for an open in CKT 465.