79 Z28 won't idle and sounds rough

Discussion in 'Troubleshooting & Diagnosis' started by Andy Jones, Nov 21, 2020.

  1. Andy Jones

    Andy Jones Veteran Member

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    Hi
    Have a 79 Z28. Rebuilt the carbs (Rochester qjet) a few weeks back and the car ran great. My son drove it here and there for a few weeks and then to college (120 miles), also great. Half way home it died. Now I can start it but it won't idle. You can keep it running on the throttle but sounds like a cylinder is missing and you can smell gas like it's running rich.
    Have just changed all the vacuum lines but no difference.
    Any help appreciated. Am at a loss.
    Andy
     
  2. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

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    Could be a bunch of things but my first guess is its electrical. Pull all the plugs. They should be a tan color but if one or more are black then I would check those cylinders first. check compression and the condition of the wires or distributor cap. If the plugs are all black/sooty then it could be the distributor or timing chain. Then again, it could be the carb. Start with the basics.
     
  3. Andy Jones

    Andy Jones Veteran Member

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    Thanks
    I pulled 2 plugs and they looked good. All plugs and wires are new
    I will check the rest and do a compression check. Was hoping to avoid this as the back 2 on the passenger side are terrible to get to. But needs must.
    Also checked fuel inlet. Pump seems to be working fine
     
  4. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

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    check the distributor cap for cracks.
     
  5. Andy Jones

    Andy Jones Veteran Member

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    It's new also but will check.
    It feels to me like a fuel issue but don't see how.
     
  6. Zspoiler

    Zspoiler Veteran Member

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    Check for vacuum leaks as well
     
  7. Andy Jones

    Andy Jones Veteran Member

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    Thanks
    Changed all the vacuum hoses
    I'm thinking it could be the float.
    Thoughts?
     
  8. berg2695

    berg2695 Veteran Member

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    I think you are on the right track. Gonna have to take the top off the Q-Jet.
     
  9. Andy Jones

    Andy Jones Veteran Member

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    Yeah. If it fixes it, it will be worth it...
    Will let you know tomorrow if it works.
     
  10. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

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    Did you adjust the timing and possibly not tighten the hold down bolt and the distributor moved? I'm just wondering how something could change so quickly.
     
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