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1986 Johnson 40 hp outboard

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  • 1986 Johnson 40 hp outboard

    Having trouble with my motor running at high speed. Idles good, run on low speed good. But when at half or full throttle, you have to continually choke it to keep it running. Been having this problem for 2 yrs. I rebuilt carburetor and replaced fuel pump and fuel lines in the fall of '99. Had same problem, and let a local marina work on it in spring of 2000. They rebuilt carburetor and replaced fuel lines. Fall of this year, I rebuilt carburetor, new fuel tank, new fuel lines and fuel pump. Still having same problem. Will run good for about 2 or 3 times out... This last time, motor has not been set up for more than two weeks... ran every other week... Has anyone got any suggestions, or experienced a similar problem? Any comments or suggestions appreciated...

  • #2
    Re: 1986 Johnson 40 hp outboard

    Hi R SloanIt sounds as if it's starving for fuel.Start with the simplest thing first,is the tank vent open? Are the new fuel lines tight? Are the o-rings in the conector good?Is the conection tight? Fuel level in bowl too low? carb to manifold gasket leaking? Look for anything that could be sucking air that is not supose to.Is this a VRO model, if so there might be a problem there. Check the synchronizing, see if throtle is opening corectly. good luck.


    • #3
      Re: 1986 Johnson 40 hp outboard

      Try to sqeeze primer bulb when problem appears. If it helps, it might be fuel pump, lines, tank, etc. Can fuel be pumped in carbureator easy, or is there unnatural resistance ? Test the ignition with a gap tester to see if sparks are strong enough.Has the carbureator been changed - do you know if main jet is big enough ??This is only my ideas of possible errors.