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  1. #1
    towrider's Avatar
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    Jun 2007

    140 FX slight backfire on full throttle


    Thanks in advance had this post on another forum but no takers, any ideas? Had the ski out today and the same slight backfire/popping at full throttle even without pulling a skier. Noise goes away after acceleration continues.Just at the start.checking plugs tomorrow am
    140 FX "slight popping" full throttle takeoff
    Well I got my new ECM in, and changed the oil, checked cleand the spark plugs and took out the ski yesterday.

    There's a slight "popping" sound coming from the exhaust when taking off from a dead stop pulling a skier at almost full throttle which later goes away.

    Everything else is fine,
    Top end/ full throttle, pulls good with good power , mid range is good too and idles great.

    I'm thinking possibly a timing issue or one spark plug.(?)

    Everything else is pretty new in there I think that the plugs have maybe 25 hours on them but one cylinder had fuel fouling from a previous problem which has been fixed.

    I took all of the plugs out they looked okay cleaned them with brake clean checked the gaps and was careful not to close the gap when installing

    Any ideas what would cause this, happens under extreme load like I said pulling me at 210 on a wake board from a dead stop is a good full load test
    Added did it today with just me and g/f on the ski, goes away after ski gets going mainly just at the first 15-20 seconds or so

  2. #2
    My buddy has a ski which is the same and it is in the shop for the same type thing--and they have not been able to find the demon

  3. #3
    depending on year check coil if coil on plug, if it has wires check your wires. Sounds like something ignition related.

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