Fuel System Supply

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.

NOTE: The gear rotor pump in the back of the high pressure pump, draws fuel from the tank, through the filter, to the back of the high pressure pump. The gear rotor pump is capable of drawing up to 20 in. of vacuum, depending on cranking speed. A specification of under 3 in. of vacuum reveals the high pressure pump suspect if there is no air intrusion into the fuel system.

Fig 1: SPECIAL TOOL #9663

Courtesy of DAIMLERCHRYSLER CORP.

1 - FUEL FILTER HOUSING ASSEMBLY

2 - FUEL SUPPLY TO HIGH PRESSURE PUMP

3 - FUEL SUPPLY TO FUEL FILTER HOUSING

4 - SPECIAL TOOL #9663

Test Set Up

Assumptions for this test are that the fuel gauge is operating properly and that there is know good fuel in the fuel tank.

Disconnect the camshaft position sensor to prevent the vehicle from starting.
Remove the bleeder screw on the fuel filter housing and install special tool fitting #9663. See Fig 1.
Connect vacuum and pressure gauge # 6828 to the #9663 fitting. See Fig 2.
Re-prime the fuel system to remove all air (Refer to FUEL SYSTEM/FUEL DELIVERY - STANDARD PROCEDURE) .
Restrict the inlet side of the fuel filter by clamping the inlet hose close to the filter assembly.
Crank the engine 3-4 times in 15 seconds intervals while monitoring the gauge.

Results

The supply pump should draw at least 3 in. of vacuum. If the supply pump was unable to reach 3 in. of vacuum, replace the high pressure pump (Refer to FUEL SYSTEM/FUEL DELIVERY/FUEL INJECTION PUMP - REMOVAL) .

If the pump was able to reach 3 in. of vacuum, continue with this test.

Fig 2: SPECIAL TOOL #6828

Courtesy of DAIMLERCHRYSLER CORP.

1 - GAUGE #6828

2 - FUEL FILTER ASSEMBLY PRIMER BUTTON

3 - FUEL FILTER ASSEMBLY

Pressure Test

This test will check the ability of the fuel system to hold pressure.

Reconnect the camshaft position sensor.
Remove the clamping pliers from the fuel inlet hose.
Pump the hand primer until 10 psi. is obtained on the pressure side of the gauge.

Will the engine start ?

Results

If the engine starts, refer to the fuel filter restriction test (Refer to FUEL SYSTEM/FUEL DELIVERY - DIAGNOSIS AND TESTING) .

If you were able to obtain 10 psi. with the hand primer, refer to SYMPTOM: *ENGINE CRANKS BUT WILL NOT START . If you were unable to obtain 10 psi. with the hand primer, check fuel supply from tank to filter assembly. If the fuel supply is OK, replace the fuel primer/filter assembly.