Fuel Pressure: Testing and Inspection

CHART 6C-2 FUEL PRESSURE CHECK












DESCRIPTION:
The Fuel Pressure Check determines if the fuel system is providing fuel pressure. The components involved include the fuel tank, sender, pump, pipes and hoses, pressure regulator, fuel rail, and injectors. Also checked are the electrical operation of the fuel pump relays. This chart requires J 34730-1 Fuel Pressure Gage.

NOTES ON FAULT TREE:
1. If fuel pump does not run at key "ON", diagnose as if a Code P020 is set to determine the cause. If fuel pump runs at key "ON", check for an open or clogged fuel line or filter.
2. If normal fuel pressure is present, then check for correct injector operation.
3. If fuel pressure is too high, then the pressure regulator is not working properly, or cannot work due to a restriction in the fuel return back to the fuel tank.
4. Fuel pressure leak down can be caused by a regulator, a fuel pump check ball, or a leaking injector. Low fuel pressure that does not leak down can be caused by a regulator or a low output pump.
5. If fuel pressure holds with Engine Compartment Fuse Block Fuse "A5" removed, injector 2, 3, 5, or 8 must have been electrically energized causing the fuel pressure drop.
6. Checking if a short to ground on the low side of the injector or the PCM was keeping the injector energized.
7. If fuel pressure holds with Engine Compartment Fuse Block Fuse "A7" removed, injector 1, 4, 6 or 7 must have been electrically energized causing the fuel pressure drop.
8. Checking if a short to ground on the low side of the injector or the PCM was keeping the injector energized.
9. Checking for a physical cause of the pressure drop ie. leaking injectors, leaking fuel rail pressure regulated. If no leaks are found the fuel pump check ball is not operating correctly then replace fuel pump.