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Stalls out on me randomly

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Me89'Jimmy, Jan 6, 2003.

  1. Me89'Jimmy

    Me89'Jimmy 1/2 ton status

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    i have a 1989 GMC fullsize jimmy and for some reason it likes to stall out on me randomly, it usually happens when i come to a stop light but only after ive been sitting there for a while, i just put in a new throttle positioning sensor, is that the problem? somebody help me please /forums/images/graemlins/k5.gif
     
  2. pfloydmaster

    pfloydmaster 1/2 ton status

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    Had the same problem. Turned out to be the battery cable to the starter.Cleaned the cable stud on the starter and replaced the cable...haven't had a problem since.
     
  3. RedBrute

    RedBrute 1/2 ton status

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    It may be the fuel pump going. Does it start up imedeately after or do you have to crank it quite a bit before it fires up?
     
  4. Highlander

    Highlander 1/2 ton status

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    Have you looked for vacuume leaks yet?

    Eric
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Was it doing this before you installed the new TPS? Did you set the idle voltage correctly when you installed the TPS?
     
  6. 90K5

    90K5 1/2 ton status

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    If your truck has a lot of miles on it, you'll want to do this one anyway...Idle Air Control...its on the TBI, jsut a sensor that scres in. Might be that when its idling it gives a bad reading, tells the comp to lower the RPM's till it dies. Even if it doesn't fix the problem, you'll have a nice smooth idle...also check ignition module, mine did that kinda stuff when it was on its way out.
     
  7. HarryH3

    HarryH3 1 ton status Author

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    The Idle Air Control motor isn't a sensor. It's a stepper motor with a pintle on the end. The computer senses RPM directly from the distributor, then uses that data to tell the IAC if it needs to drive in and lower RPM (make the air bleed past the throttle plates smaller) or drive out and raise RPM (make the air bleed larger). The IAC motor doesn't send any information back to the ECM. Each time the engine is started, the ECM drives the IAC motor all the way in, so that it knows where it can start counting the motor steps from. /forums/images/graemlins/cool.gif However, a stuck or broken IAC motor can cause the motor to stall at idle. But it's a rather expensive part to just randomly replace as a troubleshooting step.
     
  8. 90K5

    90K5 1/2 ton status

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    My IAC was only about $20 but it was at autozone...idle had been really bad, stalled on occasion, and wouldn't pass inspection
     
  9. Me89'Jimmy

    Me89'Jimmy 1/2 ton status

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    i have to crank it for a little bit and give it some gas to get it rolling
     

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