Diagnostic Procedure
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURES - CHECKING THE HIGH-SIDE FUEL SYSTEM
| TEST | ACTION | APPLICABILITY |
|---|---|---|
| 1 |
NOTE:
The Low/Supply Side Fuel System must be working properly for this test to be valid. Refer to the Service Information and Perform the Low/Supply Side Fuel System Test before continuing. Turn the ignition on.
NOTE:
This test requires two people. One person to test drive the vehicle while a technician observes the DRB readings With the DRBIII® in Sensors, read and compare the Fuel Pressure (PSI) with the Fuel Pressure Desired/SET-POINT (PSI) while test driving the vehicle under various load conditions such as idle, hard acceleration, cruise and deceleration.
NOTE:
The Fuel Pressure reading should follow (trail) closely to the Fuel Pressure Desired/SET-POINT reading. Does the Fuel Pressure reading follow closely to the Fuel Pressure Desired/SET-POINT reading?Yes --> Test Complete.No --> Go To 2 |
All |
| 2 | Turn the ignition off.
WARNING:
HIGH-PRESSURE FUEL LINES DELIVER DIESEL FUEL UNDER EXTREME PRESSURE FROM THE INJECTION PUMP TO THE FUEL INJECTORS. THIS MAY BE AS HIGH AS 23,200 PSI (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING:
FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM. Inspect the entire fuel system for leakage. Is there any evidence of leakage? Yes --> Repair as necessary in accordance with the Service Information. Perform ROAD TEST VERIFICATION - VER-2 . No --> Go To 3 |
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| 3 | Start the engine. With the DRBIII® in Sensors, compare the Fuel Pressure SET-POINT with the Actual Fuel Pressure readings.
NOTE:
If there is air in the fuel system, the Actual Fuel Pressure will oscillate above and below the Fuel Pressure SET-POINT. Does Actual Fuel Pressure oscillate above and below the Fuel Pressure SET-POINT? Yes --> Refer to the Service Information to purge air from the fuel system. Perform ROAD TEST VERIFICATION - VER-2 . No --> Go To 4 |
All |
| 4 | Start the engine. With the DRBIII® in Sensors, compare the Fuel Pressure SET-POINT with the Actual Fuel Pressure readings.
NOTE:
A sticking Fuel Pressure Solenoid is indicated by Actual Fuel Pressure gradually dropping below the Fuel Pressure SET-POINT then suddenly increasing (spiking) above the Fuel Pressure SET-POINT. Does Actual Fuel Pressure gradually decrease then suddenly increase (spike) above the Fuel Pressure Yes --> Replace the Fuel Pressure Solenoid in accordance with the Service Information. Perform ROAD TEST VERIFICATION - VER-2 . No --> Go To 5 |
All |
| 5 | Turn the ignition on. With the DRB, select Engine, System Tests and perform the following tests:
Were any problems found? Yes --> Diagnose and/or repair as necessary. Perform ROAD TEST VERIFICATION - VER-2 . No --> Go To 6 |
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| 6 | Refer the Service Information and perform the Injector Return Volume Test. Did the Injectors pass the Return Volume Test? Yes --> Go To 7 No --> Refer to the Service Information and replace injector(s) as necessary. Perform ROAD TEST VERIFICATION - VER-2 . |
All |
| 7 | Refer the Service Information and perform the Fuel Pressure Solenoid Return Volume Test. Did the Fuel Pressure Solenoid pass the Return Volume Test? Yes --> Replace the Fuel Pump in accordance with the Service Information. Perform ROAD TEST VERIFICATION - VER-2 . No --> Refer to the Service Information and replace the Fuel Pressure Solenoid. Perform ROAD TEST VERIFICATION - VER-2 . |
All |