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  1. #1

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    Aug 2022
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    Spark loss at high rom

    Got a 2002 Ultra 150. Skis been running great for years. Out last weekend and not ten minutes into the ride she bogged and died. Started back up and took off, but within 15 seconds, died again. Decided to tow her back in. Runs and idles on the trailer with the hose. When revving up, I can see loss of spark on one and three, but two stays strong. Changed plugs, same thing. Swapped out the cdi/coils with a spare I had, same thing. Checked the voltage regulator and it was bad, so changed it out with a tested good one - same issue. Compression is the same across all cylinders.

    These skis don't have a rev limiter, do they?

    Any thoughts on what I can test next?

    I just replaced with a fully charged battery and #1 and #3 still lose spark at high RPM.

    More info: Got a peak voltage tester and all coils are putting out 160v. Tested the pickup and charging circuits - both within specs. Tested all three coils for primary and secondary circuits - all within specs. Put in brand new spark plugs gapped to 0.30 Still, #1 and #3 lose spark at high RPM, but #2 stays strong.


  2. #2
    steve45's Avatar
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    Welcome aboard, huuuge1!

    How did you test the spark plugs at high RPM? I would be inclined to suspect they're not getting fuel unless you can see the spark (or lack of it).

    Yes, these have rev limiters.

  3. #3

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    Using a spark tester inline with the plug and the cap. Do you (or anyone) know how the rev limiter works? Would it just cut out cyl #1 & 3 and leave cyl #2 alone? Doesn't seem like that's how it would work, but if so, that is the symptom I'm experiencing.

  4. #4
    steve45's Avatar
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    I had a spark plug insulator break and slide down over the center electrode, causing it to mis-fire. That was a hard one to find. I doubt that you would have that many plugs with that problem.

    I've never used an inline spark plug tester, don't know how good they are. I used to sell firing indicators that you hold against the plug wire.

    Are you doing this on the trailer?

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