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1991 Johnson 60hp Idle issues

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  • 1991 Johnson 60hp Idle issues

    Hello. Long time visitor, first time poster.
    I have a 1991 Johnson 60 HP with 3 carbs. Under throttle the engine runs smooth and fantastic. At low idle the engine misses and runs rough. I've looked at many posts here and have followed the recommendations. I have changed the spark plugs (Champion) about 7 months ago when I bought the boat. I just changed them again. They look fine with a little blackness and some oil but no build up. I have cleaned the carbs and adjusted the air intake valves to 1-1/2 and to 2 turns out from seated but it still wants to miss and idle rough. My idle seems high and runs at 2000 rpm if my gauge is correct. Much lower and the engine wants to stall. During idle engine runs from 1800 to 2200 as it misses. I think I need to adjust the needle valves but I do not know how to do this. Or it could be other things. Fuel filter or ball valve maybe? I can give more info if you need but I need help please.

  • #2
    Re: 1991 Johnson 60hp Idle issues

    things I would turn do, sync$linc, idle timing, is it making temp., as your manual says to adj. in lean(clockwise) out rich(counter clock) eighth turn 15 sec to let motor respond. do that for all 3.


    • #3
      Re: 1991 Johnson 60hp Idle issues

      Thanks for the reply. I've pulled the bottom carb because I think that one is the issue and I will clean it and see what I find in the bowl. Also, I have switched from Pennzoil Semi Synthetic Oil to Mobil QuickSilver. The Mobil is an ashless oil and may help with anything getting fouled in the future. I will go through it 1 carb at a time and I hope that will solve my issue. If not, I will look into the low idle circuit. I'll report back what finally worked for me. Thanks again.