Need help and FAST!!!! 92 gmc 5.0L

Discussion in 'Troubleshooting & Diagnosis' started by bigblock665, Dec 10, 2010.

  1. bigblock665

    bigblock665 Veteran Member

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    Apr 7, 2009
    NY
    1992 1500 gmc 305 TPI... The engine does not idle for s**t!!! The idle fluctuates up and down while in park and stalls the second its in drive... I replaced fuel filter/pump. And still no better. I unhooked the coolant temp sensor on top of the intake and the fluctuating idle starts to go away but still stalls the second the truck is put in gear... I put in a new sensor and still no help, Still i have to unplug the sensor just to get the truck to stay running. Any idea's??? I need to get this done asap and cannot find help elsewhere!!!

    thanx

    joe
     
  2. bigblock665

    bigblock665 Veteran Member

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    Apr 7, 2009
    NY
    Im sorry i mean its a 305 "tbi" throttle body ..
     
  3. bigblock665

    bigblock665 Veteran Member

    1,053
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    Apr 7, 2009
    NY
  4. Philip

    Philip Veteran Member Lifetime Gold Member

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    May 30, 2006
    Marana, AZ
    Check the intake to TBI gasket. Sounds like yours has a small piece missing. This was a common problem with the fleet I worked on back in the 90's. Still never determined the cause for sure but suspected a faulty gasket, the factory gasket always blew out in the same spot and the replacement did not.
     
  5. Knuckle Dragger

    Knuckle Dragger Moderator Staff Member Lifetime Gold Member

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    Nov 2, 2002
    Waddell AZ
    EGR stuck patialy open? I've seen that a lot.
     
  6. GoldenOne7710

    GoldenOne7710 Veteran Member Lifetime Gold Member

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    Jun 23, 2004
    Athens, GA
    Also check your PCV tube. Follow the tube from the PCV valve to the TB. There's a 90* rubber elbow right where it turns into the front of the TB. Make sure that rubber elbow hasn't melted and collapsed. Most of the time when they melt....it melts a hole in the inside bend of that elbow......causing a serious vacuum leak that can cause the symptoms you describe.
     
  7. quadriderkyle

    quadriderkyle Member

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    Jan 4, 2010
    davenport iowa
    if those ideas dont work you could look at the throttle position sensor. my dads 95 tbi350 had that go bad, I dont remember exactly how it was acting as it was a while ago and not my truck but it is something to look at.
     
  8. Kamikaze

    Kamikaze Veteran Member Lifetime Gold Member

    =2^ on the EGR Valve and Gaskets.

    Pretty common on TBI GM vehicles
     
  9. bigblock665

    bigblock665 Veteran Member

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    Apr 7, 2009
    NY
    So your talking about the gasket between the throttle body and intake manifold?
     
  10. bigblock665

    bigblock665 Veteran Member

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    Apr 7, 2009
    NY
    someone has put a straight line on that, no elbow.
     

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