Chart A-5 Engine Cranks But Won't Start (Fuel System)

Chart A-5:

Wiring Diagram:

CIRCUIT DESCRIPTION:

When the ignition switch is turned "ON," the ECM will energize the fuel pump relay which turns "ON" the in-tank fuel pump. It will remain "ON" as long as the engine is cranking or running, and the ECM is receiving distributor reference pulses. If there are no reference pulses, the ECM will de-energize the fuel pump relay which will shut "OFF" the fuel pump within 2 seconds after ignition key is turned "ON" or the engine stops.

The fuel pump will deliver fuel to the fuel rail and injectors, then to the pressure regulator where the system pressure is controlled. Excess fuel pressure is bypassed back to the fuel tank. When the engine is stopped, the pump can be turned "ON" by applying battery voltage to the test terminal located in the engine compartment.

Improper fuel system pressure may contribute to one or all of the following symptoms:

^ Cranks but won't run.
^ Code 44 or 45.
^ Cuts out, may feel like ignition problem.
^ Hesitation, loss of power or poor fuel economy.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS/ECM CONNECTOR IDENTIFICATION for correct color code identification of circuit.

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

1. This test checks the fuel pump relays power circuit (839) and ground circuit (450).

2. This step determines if the fuel pump circuit is being controlled by the ECM. The ECM should energize the fuel pump relay and turn the fuel pump "ON."

3. This test checks for an open in circuit 465.