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backfire through exhaust

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by scrappyk5, Sep 17, 2003.

  1. scrappyk5

    scrappyk5 1/2 ton status

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    sometimes when i go down the road , and the rpms are up ,
    but i have to let off the gas to coast , i will get a load backfire through the exhaust , what could that be ?
    it doesnt do it all the time /forums/images/graemlins/thinking.gif
     
  2. R72K5

    R72K5 Banned

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    check for any exhaust leaks like at manifold-to-head pipes, or at any pipe seams/joints,

    sometimes when raw unburned fuel getsignited int he exhaust system when theres an exhaust leak, even if its small and unnoticed, check carefully for leaks with engine running, have them welded. carb may be allowing too much fuel for y0our engne,.pull spark plugs and make sure they are light grayor tan andnot dark brown or black
     
  3. scrappyk5

    scrappyk5 1/2 ton status

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    sounds like the culprit with the exhaust leak. i think i
    have a very small one at the muffler. i will check the fuel/air mixture also. thanks
     
  4. loudnowlouder

    loudnowlouder 1/2 ton status

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    i've had it happen before if the timing was off a little, still started and ran fine, but wasnt getting a complete burn when the engine wasnt loaded..
    but i'll admit it mostly happens when i shut the engine off when its timing related, something else to check real quick though
     

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