Chart A-4B Fuel Pressure Out of Range Diagnosis

Diagnostic Chart.:

Fuel System Wiring Schematic:

DESCRIPTION:

This procedure tests for proper operation of the fuel delivery system while the engine is running and for the ability of the fuel system to maintain pressure at key off.

NOTES ON FAULT TREE:

1. Fuel pressure should be 32-38 psi depending on engine load and altitude.

2. By disconnecting the vacuum hose, engine load compensation is taken away from the fuel pressure regulator. Pressure should rise to approximately 45 psi. If fuel pressure is higher than 50 psi or lower than 40 psi, go to chart A-4A to diagnose fuel delivery problems.

3. Fuel pressure should hold steady at key off. If pressure bleeds down the vehicle may exhibit extended cranking time upon restart. Pressure bleed down means that either the pressure regulator can't hold pressure, the fuel pump check ball is not seating, or an injector is sticking open.

4. At this point the fuel system has checked out OK. If any oxygen sensor codes were set, go to the appropriate chart listed. If a customer complaint still exists, go to DIAGNOSIS BY SYMPTOM.