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Significant Loss of Power, Throttle hesitation with 1984 9.9hp Evinrude

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  • Significant Loss of Power, Throttle hesitation with 1984 9.9hp Evinrude

    So here's the background story. I recently acquired a 1984 Evinrude 9.9hp outboard model: E10BALCRA, AC Lighting rope start. It started well when tested but then would not start after purchase and i took it into shop where they charged me for a couple hours work to fix what they said was an electrical problem (was told some wires were loose under the fly wheel and were shorting out the motor).
    So the shop got it starting for me and i took it out for a run on my 14 ft alum fishing boat. The motor ran well initially with the exception of acceleration not being so smooth on the throttle (throttle hesitation?) - motor would not power at same rate of throttle being turned, and you had to full throttle it to get it going and then could decelerate to less than full throttle.
    Anyhow, so it ran well for about 5-6 hours of maneuvering about at various throttle speeds and with multiple breaks for fishing. Then I had to run it in full throttle in reverse (not sure if related to problem) to avoid collision with a barge coming around an island, and have been having the following problem since:
    The problem started to present like the engine was running out of gas, sputtering and losing power (had plenty gas). When at full throttle the motor would just slow down and run at about half power. It would go between running at half power for a few minutes to back up at full power without having changed the throttle. Kind of felt like the engine was getting overheated or it was not getting fuel. Sometimes it helped to turn it off for a few minutes and let it cool off, but eventually before making it back to the ramp, it only would run at half power. I tried taking it back on the water again and it will still run but at about half the power that i know it is capable of.
    I was lucky to be able to take a couple video clips and are attaching two videos to show engine running. Both are at full throttle, one when running well and the other when experiencing the above mentioned decreased power. You will be able to see and hear (sputtering) the difference in how the engine runs. Just want it running well again.
    Please advise and help me diagnose the problem. I really can't afford to take it back to the shop again. Thanks for your help.

  • #2
    Re: Significant Loss of Power, Throttle hesitation with 1984 9.9hp Evinrude

    I'd say it's a bad ignition coil (or loose connection to the coil). A weak coil will shut down when it starts getting hot thereby dropping a cylinder and causing the symptoms you describe. It's tough to accurately test a coil with a meter (or, should I say, it's tough for me to test a coil). Hook up an induction timing light on the top plug wire and watch for intermittant flashes, then check the lower plug wire and do the same. This test will show you a weak coil. Did the shop elaborate at all as to what wires they worked on?
    United States Coast Guard Officer #1172938
    Catamount Marine


    • #3
      Re: Significant Loss of Power, Throttle hesitation with 1984 9.9hp Evinrude

      here is a electrical diagram.

      start to check spark first, to confirm if ignition works well
      if ok, then check copression at both cylinders(should be equal and more then 80 psi),
      its good to clean the carb , put apart and clean all with carb cleaner soakink over night, and blow witch compresion air,
      Attached Files


      • #4
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        Re: Significant Loss of Power, Throttle hesitation with 1984 9.9hp Evinrude

        The shop only said some wires were loose and were shorting the engine. I'm been up trying to research this problem. One thing I just found and rectified was a problem with the throttle twist grip gears on this model motor. They were out of sync, and i have just corrected it. I really hope this is the only problem. Posting a couple pics of what was off. If not i will look into your recommendation. Thanks.
        Click image for larger version

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