>>94' GMC Jimmy fuel pump/ fuel pressure problems.<<

Discussion in 'Chevy Blazer Forum (GMC Jimmy)' started by Cowpar2, Sep 12, 2013.

  1. Cowpar2

    Cowpar2 New Member

    I have a 94' GMC Jimmy, and I believe I'm having problems with the fuel pump.
    It starts up just fine every time, but after driving it awhile it starts to act as if it's running out of gas. This happens especially on hills, and it will stall if I don't baby the gas pedal. I've replaced the fuel filter, and the fuel pressure is fluctuating between 45-55 psi.
    I think it's the fuel pump dying, my friend thinks it's the regulator, I've heard it could be the coil or a vacuum leak, is there any way to be certain?
    Sorry if this sounds like a dumb question, this is my first vehicle!
  2. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 1000 Posts

    Need to move this to the Blazer / Jimmy section.
  3. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    Welcome to GMTC! I know on the newer trucks you can check if the regulator is bad by unplugging the vacuum line running to it. If fuel comes out then there is a leak in the diaphragm and it is bad. I am not sure on the older models. You can always try it. 45-55 is a large fluctuation.
  4. the phantom

    the phantom Epic Member 5+ Years ROTM Winner 1000 Posts

    Not sure if thats a fuel pump or not but in a 98 and 99 jimmy I had, usually the fuel pump if it was getting weak wouldnt start it because it required 65psi to start and only 55psi to run. but the 99 was doing exactly what your describing. mine would start up and run and as soon as it started to get warm it would lose power and could only go about 10-15mph and barely if at all make a hill. Wait for it to cool down. start right up go for a bit until warm then back to 10mph. thought it was vacumn line related or something that changes at almost running temperature. Never found out what it was I sold it!!!
  5. rudeboi619

    rudeboi619 New Member

    i would put my money on either a vacuum leak or the little black pressure sensor that is on top of the fuel pump. i have a 98 that has this problem and i have replaced the whole ignition system and it was no help. i have read that those pressure sensors are made way cheap and damage easily. replacing mine is probably my next step whenever i have the 50 bucks to get a new one. i will let you know if it works

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