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  1. #1
    michael dever's Avatar
    michael dever Guest

    Default " Was hoping a post might give

    " Was hoping a post might give me some ideas on what to check on my 1992 120hp Johnson. I have it on an 18' Starcraft and while on plane running at ~80% throttle, the motor will slowly increase rpm and boat speed. Maybe like someone has increased the throttle position or its getting more gas. When I ease the throttle back enough to lower the rpm, its always too much and goes off plane. There does not seem to be a sweet spot for running less than full throttle.
    I have replaced the fuel filter and recently tuned it up but this condition seems to be getting worse over time.

    Any advise?

    mtd "

  2. #2
    Join Date
    May 2001

    Default "Mike, Sounds like a strang


    Sounds like a strange problem.

    My only guess is that there is a problem with the fuel system, causing the engine to run very lean. This can cause the rpms to increase. Then, when you decrease the throttle, the engine rpms drop off rapidly due to lack of fuel.


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