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  1. #1

    951 Engine RPM problems when hot, Great when cold

    Hi Everyone,

    1999 Seadoo XP with 951 carb engine

    Original Problem:

    Purchased a low compression running seadoo. One piston was missing chunks, appeared to have been run lean

    Rebuilt Top End, Bottom end disassembled to clean/check for piston debris. Passed leak-down test. Rebuilt carburetors, changed all fuel lines, cleaned selector valve. Cleaned Rave valves. Changed out gaskets etc during tear down. Compression 130. Clipped Ignition wires. New Plugs.

    For the first 10 minutes the boat runs great with full RPM range. After 10 minutes RPMS won't go above 2200, then engine starts surging from 1500-2200 whether partial or full throttle. Put the boat on the trailer and it runs fine with full RPM range.

    Actions taken so far:
    Went through the carbs again, bypassed the selector valve just for peace of mind. The water valve was rusted but the rubber boot was good.

    Look forward to suggestions.

  2. #2
    SURFnTURF's Avatar
    Join Date
    May 2007
    Check the compression again.It may have done the same thing.

  3. #3
    Compression is fine.

  4. #4
    fuel delivery or tank venting

  5. #5
    AndinoWatercraft's Avatar
    Join Date
    Feb 2008
    Puerto Rico
    How the plugs are coming out? Notice any excesive smoke inside the hull? Check the exhaust hoses this could choke the engine.

  6. #6
    Myself's Avatar
    Join Date
    May 2007
    North Central Arkansas
    While it is experiencing the symptom check the voltage at the battery while running and giving it throttle. You can do that easily by loading it onto the trailer and just keep it in the water. Sounds like it could be electrical, stator or rectifier.

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