Mechanics

IRRATIC THEN NO FUEL PRESSURE

2002 Jeep Grand Cherokee • 128,000 miles

Have a 2002 GC with a 4.0 L. Recently noticed a problem re-starting once it had been driven for a while and then sits for several hours. Plus there was a 'squeaking noise' near the tank that sounded almost like a pump oscillating on/off/on/off. Concerned the fuel pump was going bad, I changed two weeks ago. The noise is still there (maybe gone for a few days). Two days ago after driving 2-3 miles the Jeep lost power started missing and died. After sitting for a while it would restart but repeat this process. I changed the fuel pressure regulator/filter last night and drove around the block. Died 1/2 way. Finally was able to check the fuel pressure. Around 44 psi with key on - seems to hold but I didn't leave in sitting very long. Started and at idle around 54 psi. After 3-5 minutes as the Jeep reached operating temp the pressure gauge needle started vibrating very fast between approximatley 50 - 55 psi. Soon after the gauge dropped to 40, 30, 20 then to around 0-5 psi, all in about 10 seconds. Up until then the Jeep seemed to be running OK, maybe a LITTLE rougher idle, but soon after the pressure drop the idle became very rough on it died (as expected). Concerned I never really had a bad fuel pump but do now. Could there be something else causing the pump to essentially quit or drop pressure. As noted I changed the regulator/filter and the Jeep did the same thing. Thougths?
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JimmyP
June 7, 2012.



Seems like you got a bad replacement fuel pump. It seems to be failing after running for some time and I believe that is where you should be looking at.

After engine stalled and when there are no fuel pressure, test the fuel pump operations and check for power supply to the fuel pump.


KHLow2008
Jun 7, 2012.
Check the oil pressure switch to see if it is making a good connection as that keeps it running. But scan for codes as well. Pressure should be 44-54 with engine idling. The only other thing I can think of is maybe some type of blockage in the tank or a kinked line that would be causeing this. Check yoru fuel pump strainer in the tank.


Hmac300
Jun 7, 2012.