Question about 1994 GMC Sierra

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Engine runs rough

I tried changing the plugs but that did not work. I tried unplugging 1 fuel inj. and it will run a little better but if I plug both of them up it runs like ****. The only way to get it to start is by holding the pedal down to get it started.

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  • 5 more comments 
  • snowman_1972 Apr 18, 2009

    there is no check engine light or anything

  • snowman_1972 Apr 18, 2009

    the engine is a 5.7 litre

  • snowman_1972 Apr 18, 2009

    The only problem now is you have to let the truck warm a few minutes or as soon as you try to give it any gas it stalls,and you have to hold the pedal down to get it started. I was wondering if that is because the sensor is unplugged. Thank you for the help so far.

  • snowman_1972 Apr 20, 2009

    I unplugged the temp. sensor and the truck runs better but you have to hold the pedal down to get it started. I have to let it warm up for a couple of minutes or else as soon as you give it any gas it stalls if you let it warm up some it seems to be ok. The temp. sensor is still unplugged because if I plug it back in it runs bad.

  • snowman_1972 Apr 20, 2009

    I am also getting a check engine light now but I figured it was because the temp. sensor is unplugged.

  • snowman_1972 Apr 26, 2009

    I replaced the temp. sensor and the truck runs great thank you for the advise and help.

  • LUIS AREVALO May 11, 2010

    the check engine is on yes or no the car engine side is 5.7l TBI


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Do you have a check engine light. Try unplugging the coolant temp sensor.

Posted on Apr 17, 2009

  • 2 more comments 
  • Clint Smock
    Clint Smock Apr 19, 2009

    If you still have to hold the pedal down then the coolant temp sensor likely isn't the problem, so plug it back in if it didn't help. Does it also stall with the coolant temp sensor unplugged. Do you see any gas dripping from the injectors when you have someone cycle the key but don't crank it?

  • Clint Smock
    Clint Smock Apr 20, 2009

    The coolant temp sensor is fairly inexpensive. Just replace it and see what happens. You are right about the CE light, after you replace the temp sensor, unhook the battery to clear the code for the temp sensor.

  • Clint Smock
    Clint Smock Apr 20, 2009

    Have you checked fuel pressure?

  • Clint Smock
    Clint Smock Apr 27, 2009

    Glad I could help. You wouldn't believe how hard it is to diagnose this stuff without looking at the vehicle.


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