Fuel Pressure Leak Down
FUEL PRESSURE LEAK DOWNPOSSIBLE CAUSES
- Faulty Fuel Pump Module
- Fuel Injector(s)
Diagnostic Test
1. FUEL PUMP MODULE
NOTE: Before continuing visually and physically inspect the fuel delivery system for external leaks or damage. Repair/replace as necessary.
Turn the ignition off.
WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE (EVEN WITH THE ENGINE OFF). BEFORE TESTING OR SERVICING ANY FUEL SYSTEM HOSE, FITTING OR LINE, THE FUEL SYSTEM PRESSURE MUST BE RELEASED. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
Install special tool #6539 (5/169) or #6631 (3/89) fuel line adapter.
Install the fuel pressure gauge.
Start the engine and allow the fuel system to reach maximum pressure.
Turn the ignition off.
NOTE: Fuel specification is 407 KPa ± 34 KPa (59 psi ± 5 psi).
Using special tool #C4390, Hose Clamp Pliers, pinch the rubber fuel line between the fuel pressure gauge and the engine.
Monitor the fuel pressure gauge for a minimum of 5 minutes.
NOTE: The pressure should not fall below 241 KPa (35 psi)
Q: Does the fuel pressure drop?
YES: Replace Fuel Pump Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 2
2. FUEL INJECTOR(S)
WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE (EVEN WITH THE ENGINE OFF). BEFORE TESTING OR SERVICING ANY FUEL SYSTEM HOSE, FITTING OR LINE, THE FUEL SYSTEM PRESSURE MUST BE RELEASED. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
Remove special tool #C4390.
Start the engine and allow the fuel system to reach maximum pressure.
Turn the ignition off.
NOTE: Fuel specification is 407 KPa ± 34 KPa (59 psi ± 5 psi).
Move special tool #C4390, Hose Clamp Pliers, from between the fuel pressure gauge and the engine to between the fuel pressure gauge and fuel pump module.
Monitor the fuel pressure gauge for a minimum of 5 minutes.
NOTE: The pressure should not fall below 241 KPa (35 psi)
Q: Does the fuel pressure drop?
YES: Replace the leaking fuel injectors. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Test Complete.