1. 94 grand Cherokee won't stay running

    Hello I have a 94 grand 4.0 my jeep stopped running about a month ago . I finally got a couple things fixed on it but it when I start it . It old stays running for about 30 sec. and then dies. I replaced the fuel pump and the fuse for the ignition coil . I also have checked the relays all good I think . Would love some help if anyone knows what I failed to check.
    thanks.

  2. #2
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    Re: 94 grand Cherokee won't stay running

    Possible that the fuel pressure regulator is stuck open . Pull the vacuum line off from the regulator to see if there is any change in rpm or the problem. If you have a fuel pressure tester you can check pressure with vacuum line on and off. Verify that there is vacuum read from the vacuum line first.
    Never overlook the obvious . It's usually right in front of us

  3. #3

    Re: 94 grand Cherokee won't stay running

    I also heard the crank shafts position sencer can also be an issue . I thought it worked or it didn't .

  4. #4
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    Re: 94 grand Cherokee won't stay running

    Before we just grab straws and try throwing parts at it , how about some history as to what work has been done so far. Since some brands of new parts have been found to be troublesome , could you tell us what work/ parts have been done/replaced ? BTW , have any dtc's ( diagnostic trouble codes ) been found ? I realize the engine won't stay running long enough to set a code but have any been logged at all ? A crank sensor is what tells the pcm what position the engine is in to start the ignition and injection timing to start the engine . The cam sensor follows in advance when the engine is accelerated much like a distributor vacuum and centrifical advance but in electronic parameters to communicate information to the PCM. The fact that the engine starts and runs ( even for just a moment) suggests the ignition is working due to feedback from the crank sensor and cam sensor but these sensors should be checked to be sure. We cannot assume they're not part of the problem. I still feel the fuel system ought to be checked for pressure readings . A fuel pump,was installed but is pressure adequate . Lots can happen in the fuel,system . A bad check valve in the pump , hose connection leak from pump,to sending unit causing pressure drop , leak in line to fuel rail , etc. . Just some thought , please tell us what you know based on my questions hoping to,give some insight . Hope this helps . Greg
    Never overlook the obvious . It's usually right in front of us

  5. Re: 94 grand Cherokee won't stay running

    Have you checked the crank shaft sensor?

  6. #6

    Re: 94 grand Cherokee won't stay running

    Thanks Greg
    it was running fine.
    OK I replaced the fuel pump , the fuel pump relay and engine coil fues.and that's it so far.

  7. #7
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    Re: 94 grand Cherokee won't stay running

    Thanks for your reply. Yes you did mention the fuel pump swap and ignition coil relay and fuse. Sorry I missed that . Still curious of fuel pressure readings . Hoping you can get a pressure gauge to check this ? I should ask if there could be any possibility of a vacuum leak but want to know first if the engine is idling at a normal idle rpm when it starts before it stalls. If the idle air control motor is opening as it should , the idle should increase above normal idle speed . If the engine sounds rough and uneven then I really questioning fuel delivery. Spark quality needs checking with an in line spark tester when starting as well. Good to start with the simple basic things .
    Never overlook the obvious . It's usually right in front of us

  8. #8

    Re: 94 grand Cherokee won't stay running

    Thanks everyone who posted , jeep is running now it was the auto shutdown relay and ignition coil 30 amp fuse. The fuel pump went out at the same time . Do not know what caused it but did have a really bad rain storm with big rain puddles. That's when jeep quit working.
    thanks again
    Gary

  9. #9
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    Re: 94 grand Cherokee won't stay running

    Glad you found the fault. I don't know what lead me to get so fixated on the fuel pump pressure and not give consideration to power to the pump . Sorry I did not suggest to check this but didn't think at any time that your jeep was loosing power to the fuel pump. Guess I fell victim and overlooked the obvious. Good job . Greg
    Never overlook the obvious . It's usually right in front of us

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