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Discussion Starter #1
Hi, Im new ro the Jeep world having recently acquired a 99 Grand Cherokee with a 4.0 engine. I really love it need some opinions on this problem . It runs fine for a while and then suddenly it starts bucking like its starving for fuel. Then within a minute or so, completely quits. It wil restart for 2 or 3 seconds and die again. If I let it sit for an hour or so, it starts up fine and I can drive away. I replaced the Fuel filter, no help. Could it be an intermittent fuel pump problem or maybe a problem with the fuel pump relay? Ive never seen an intermittent fuel pump but who knows. Could it be debris in the tank clogging the fuel intake screen? It was sitting for a while before I got it. Im really not sure and don't want to just randomly replace parts hoping to find the problem. Any thoughts or suggestions would be appreciated. Thanks for any input.
 

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The beast from Brazil
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Welcome to the garage.
When the problem is there and you switch the ignition to RUN, do you hear the fuel pump run for a few seconds? If it does, you have to check if there is fuel pressure in the fuel rail. I don't know the 4.0, but there probably is a shräder valve where the pressure can be checked. Best would be to check the actual fuel pressure with a gauge, but if you don't have one, you can at least press the schräder valve with some pointed tool and check for fuel under pressure to come out. Keep a rag at hand to catch the fuel. If there is no pressure, but you could hear the pump, then probably the pump is bad. If you could not hear the pump, then switch the fuel pump relay with the horn relay for trouble shooting.
 

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Welcome again!
Hope you had a chance to try Frango's 'field' test to see if the fuel rail is pressured or not.
Only other thought I had was possibility of broken( breaking) wire to the fuel pump--hence the intermittent nature of your problem.
Is a whopping big job to replace the fuel pump as its inside the fuel tank and obliges a full day- even with a helper. A little bit longer if you have a tow bar.

She's a '99 and the wires get brittle with age. Would suggest examining them too to round out the diagnosis.They are pretty well protected ( up above the tank) but the leaders to the connections could be snagged by anything if out off the pavement.

Hope this helps and you're back on (or off) the road soon! Keep us posted, ok? GL!

 

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Discussion Starter #4
Thanks for your suggestions. Next time it hapoens, I will check the fuel pressure at the schrader valve and I will go from there. I will post if that shows a problem
 
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