Backfire at idle
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Backfire at idle

  1. #1
    The Great Humongous P-Money's Avatar
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    Question Backfire at idle

    I keep getting a sporadic backfire out the exhaust at idle. Let it run on the trailer for 20 minutes yesterday and after it started to warm it the popping began. Gas is good, distributor cap is new. Starts right up, idles smooth, just has this goofy backfire out both headers. Not continuous, seems to come and go. Plugs look good.

    468, 660s, 990s, msd pro billet distributor, crane hi-6, bg280, bassetts...

    Any thoughts where I should be looking?

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  3. #2
    Platinum Member BigSteve's Avatar
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    Just a wild hair guess but I had friends twin engine boat backfire at times on one engine and quit at other times when warm, I found a ignition switch getting hot. put a new switch in no more problems
    If you ain't the lead dog the view is always the same !

  4. #3
    Senior Member SoldHondaBoughtHondo's Avatar
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    Missfire...or full blown backfire? Might try slidding the spark plug boots off the plugs with a grounded or insulated screwdriver....just far enough so the spark has to jump inside the boot...it will get you one of 4 things.

    If the miss fire stops, and the motor runs better it's probably a spark plug problem

    If it runs worse and the misfire stops it probably a wire.

    If it misfires the same and runs worse, it isn't that cylinder.

    And if ya get knocked on your ass ya probably don't know what a grounded or insulated screwdriver is
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    Senior Member TwinTurbo540's Avatar
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    Headers? Wht do the exhaust gaskets look like?
    I like my women like I like my boats......Fast and ready to get wet at all times!!

  7. #5
    I'm No Expert Shaun's Avatar
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    Quote Originally Posted by TwinTurbo540 View Post
    Headers? Wht do the exhaust gaskets look like?
    X2, i had a issue that chased down for days where it would back fire when i gave the throttle a slit blip on the trailer. Turned out it was my exhaust gaskets leaking. From what i was told you end up letting fresh cool air get sucked back into the motor and it causes a lean backfire.

  8. #6
    Senior Member motormonkey's Avatar
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    Check your Crane ignition box. Ive ran a into similar problem with them before.

  9. #7
    Senior Member TwinTurbo540's Avatar
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    Quote Originally Posted by Shaun View Post
    X2, i had a issue that chased down for days where it would back fire when i gave the throttle a slit blip on the trailer. Turned out it was my exhaust gaskets leaking. From what i was told you end up letting fresh cool air get sucked back into the motor and it causes a lean backfire.
    Yup, seen it more than once!! Sometimes it just something simple that gets over looked..

    Travis
    I like my women like I like my boats......Fast and ready to get wet at all times!!

  10. #8
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    I had a Crane box go bad but it had a miss from 3000 rpm and up.

    Tim

  11. #9
    Frst Round Runnerup Hondog's Avatar
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    Quote Originally Posted by TwinTurbo540 View Post
    Yup, seen it more than once!! Sometimes it just something simple that gets over looked..

    Travis
    X3.

  12. #10
    Gone
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    Pull the valve covers and check things....just because.

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    Senior Member Schiada 201's Avatar
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    X 2

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    Senior Member Widetrack's Avatar
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    Flat tappet cam or roller?


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  15. #13
    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by Widetrack View Post
    Flat tappet cam or roller?
    I know where you're going with this...been there, done that > and it sucks
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  16. #14
    Senior Member YumaJet's Avatar
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    Quote Originally Posted by HammerDown View Post
    I know where you're going with this...been there, done that > and it sucks
    Quote Originally Posted by Widetrack View Post
    Flat tappet cam or roller?
    x2
    boatless....

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