Fuel Delivery and Air Induction: Testing and Inspection

Fuel System Diagnosis

WARNING: The fuel system is under pressure. To avoid fuel spillage and the risk of personal injury or fire, it is necessary to relieve the fuel system pressure before disconnecting the fuel lines.

WARNING: Do not pinch or restrict nylon fuel lines. Damage to the lines could cause a fuel leak, resulting in possible fire or personal injury.

Circuit Description
The fuel pump is an in-tank type mounted to a fuel sender assembly. The fuel pump will remain on as long as the engine is cranking or running and the Engine Control Module (ECM) is receiving reference pulses from the crankshaft position (CKP) sensor. If there are no reference pulses, the ECM will turn off the fuel pump two seconds after the ignition switch is turned ON or two seconds after the engine stops running. The fuel pump delivers fuel to the fuel rail and the fuel injectors, where the fuel system pressure is controlled to 310 kPa (45 psi) by the fuel pressure regulator. The excess fuel is returned to the fuel tank.

Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump fuse from the engine fuse box.
3. Start the engine and allow the engine to stall.

Steps 1-6:

Steps 6 (continued)-19:

Steps 19 (continued) & 20:

4. Crank the engine for an additional 10 seconds.