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1981 9.9 missing

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  • #1

    1981 9.9 missing

    I have a 1981 Evinrude 9.9 on my fishing boat. Been a great engine, low hours, very dependable. This past weekend while going through no wake zone I started to lose a cylinder, out in the open running fast ran fine....come back to the no wake zone, cylinder gone again. So, start with spark plugs. Probably the original set, one was wet with fuel, the other not so much, electrodes well worn, so I started there. Played around to see if it was the plugs or wires switched wires went out again and ran great until I came back to the no wake zone again. Went out and got new plugs figured that was the problem. Made no difference. It now is basically running on one cylinder as it won't run on both cylinders even at fast speeds now. Thinking perhaps coil? An expertise would be great.

    Thanks, CP
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  • #2
    Best to check the compression... what are the psi compression readings of both cylinders?

    With s/plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? (The gap is important).

    S/Plugs should be Champion QL77JC4 plugs gaped at either .040 (strong spark) or .030 (longer life).

    Let us know what you find.

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    • #3
      Originally posted by Joe Reeves View Post
      Best to check the compression... what are the psi compression readings of both cylinders?

      With s/plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? (The gap is important).

      S/Plugs should be Champion QL77JC4 plugs gaped at either .040 (strong spark) or .030 (longer life).

      Let us know what you find.
      I don't believe it is compression. The spark comes and goes directly effecting the performance. I can't decide if it is the coil or the plug wire.

      Comment

      • #4
        Originally posted by Captain Planet View Post
        I don't believe it is compression. The spark comes and goes directly effecting the performance. I can't decide if it is the coil or the plug wire.
        Switch the coils... If the problem follows the coil, then the coil is faulty.

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