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85 GMC Jimmy back firing

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by GloNDark, Sep 4, 2002.

  1. GloNDark

    GloNDark Registered Member

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    Well I put a different exhaust on my 85 jimmy, and now it backfires like a MO FO! Runs great until you let off the gas....and then poof poof poof BANG!!! :O What a noise.

    Could an exhaust leak cause this? The timing is right on, the carb seems to be in good adjustment. But I noticed an exhaust leak where the exhaust manifold meets the exhaust pipe.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah, my car would do that when I had a fairly bad leak at the manifold/exhaust pipe mating surface. ONLY when I let off the gas quickly though of course.
     
  3. Calclips

    Calclips 1/2 ton status

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    I have a problem with this, I'm gonna get rid of the glasspacks and weld up a few holes that are in the headers. I think its a backpressure issue with mine.
     
  4. JW86

    JW86 Registered Member

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    had the same problem, found i was missing the last manifold bolts on each side of the the engine! After putting in the bolts and tightening up the problem stopped, but started again in a few days - bolts loosened up again. expect i will have to put in new gaskets and put in new bolts all that way around, but seems like that may be a good place for you to have a look! LOL /forums/images/icons/cool.gif
     

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