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50 HP 2 Stroke not running at WOT

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  • 50 HP 2 Stroke not running at WOT

    Ok - after much searching i still have questions, I will try to explain, fully, the problem. I am new to outboards but am a mechanically inclined motorcycle tech.

    Motor is a 1998 mercury 50 hp 2 stroke,
    The problem is that the engine does not seem to want to run at "high idle".

    When starting - lift high idle lever, push in choke button with key, turn key and she starts right up. Runs up the tach to wherever high idle lever is set. When warmed up she is ideling ok.

    When running - the rpm wont go over 3000, even at WOT. It appears as if the engine is either flooding or being gagged. There is no sputtering or misfire, engine sounds fine and the tell tale is working (warm water, not hot, good stream). The interesting part is that when running at WOT and the tach is at 3, if you push the choke button in, the engine takes off, jumps up on the tach like it should and sounds completely different like it reaches a "high idle". Is there a selenoid or something that could be keeping the engine from reaching full potential or is this just as simple as a high idle needle jet in one of the carbs.

    Was hoping someone could guide me before I start tearing into the carbs first.

    Thanks in advance!!!

  • #2
    Re: 50 HP 2 Stroke not running at WOT

    I would say your carbs are gummed up, but from what you say they are may not be that bad. You could try seafoam to try and clean them up. I have used it before when the carbs were not fouled too bad.
    If that don't work then you need to check the whole fuel system starting at the tank working forward looking for restrictions and air leaks. Either one would cause you to not get enough fuel at wot. When you get to the end of the fuel system you'll be down to the carb clean and rebuild them.

    When I get a motor in the shop that's new to me,
    I do a compression test.
    Spark test
    This tells me, what the over all shape the the motor is in
    It's a good idea to do, low compression on one cylinder would not let it come up to speed as well.

    reply back with your findings
    BT1 USN ret


    • #3
      Sign up today
      Re: 50 HP 2 Stroke not running at WOT

      Thanks for the info - will post findings later today or tom. - runnin out of days in the northeast , getting cold.