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  1. #1

    Join Date
    May 2008

    Rough idle after startup question

    Hello all,

    2012 300X, 150 hours, SCOM and no other mods. I change the exhaust filter every 2 years out of habit as well as the plugs..

    When I go to start the engine after shutting it down while in the water, and having it sit for a few minutes the engine will sound like it's missing. Usually a few blips of the throttle will clear it up. I noticed it early in the summer and decided to change the plugs figuring one was fouled. They looked all fine except some mild rust deposits. It still did the same thing after replacement so I then checked the filter which is due to be changed next season and that is fine as well. It doesn't do it on the trailer so it leads me to believe some steam may be fouling the plugs if there is water in the waterbox. Any other ideas?

    Thanks for the help...

  2. #2
    gunner12's Avatar
    Join Date
    Jun 2020
    Not sure if the 2007 ultra 250x has the same filter but I'm experiencing the same kind of issues.

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  4. #3
    dcuhpw's Avatar
    Join Date
    Jan 2019
    There is no exhaust filter on the 250x. My guess is you may be experiencing heat soak when you shutoff your ski. If you turn it back on a few minutes after shutting it off your likely getting a lean run condition until water starts to circulate back through and the temp sensor sees the actual temps which would cause the ecu to Richen yo the fuel. Just a guess but it happens on my 15f all the time and is a well known and documented “hot start” issue. Didn’t know if the ultras had the same issues but I suppose it’s quite possible.

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