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  1. #1

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    2007 STX 12F stalls and wont go past 5k RPM in water, idles and hits 7k RPM on land

    2007 STX 12F stalls and wont go past 5k RPM in water, idles and hits 7k RPM on land

    The jetski was running perfectly until a couple outings ago..
    Up until a few outings ago, I was getting 60+mph (according to the dream-o-meter)

    The machine has 31 hours on it.

    Not sure what the heck happened...but became harder to start, stalls more, and I lost my top speed.

    At the moment..I am now only getting about 43mph (70-75km/h)

    I did the fuel filter at 22 hours...and I just changed the spark plugs today..which is what I thought the cause was.

    To get it started again when it was giving me trouble and harder to start...I kinked the return fuel line purposely to raise the fuel pressure...but I actually have an adjustable fuel pressure meter on the machine and everything seems to be in order there.

    I replaced the fuel pump with a Walbro at 22 hours as well.

    Any ideas? Anyone have a similar problem with something completely off the wall?


  2. #2
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Did you check the compression or look for exhaust leaks? Is the idle motor still working?

    Check that the prop spins freely as well.

    Sean

  3. #3

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    I checked compression...It was about 220, 215, 215, 205 (pto) site. Do you test compression with the throttle wide open? I also tested it when it was hot.

    How do I test for exhaust leaks? Does that have to be done in the water?

    I don't know what the idle motor is...but that limits the rpm on land? How do I test that?

  4. #4
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Yes, throttle must be fully open during the compression Test.

    Check the thread in my signature, you have done most of it already but give it a read through.

    Sean

  5. #5

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    how would I check that the prop spins freely? isn't it connected to the crankshaft? wouldn't it have a tonne of resistance on it regardless?


    how do I check for an exhaust leak? in the water? or can I plug a hose up to it?

  6. #6
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Pull the pump off. Its not too bad. Run the engine on the hose and feel around the exhaust hoses for leaks.

    Sean

  7. #7
    CJ River Rider's Avatar
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    I had the same problem as you last year, mine turned out to be an exhaust leak. Ski has been perfect since. Good luck.

  8. #8
    +1 on the exhaust leak. Run the ski in the water and pull the plugs. Look for little droplets of water on them. They can cause the ski to misfire under load.

  9. #9

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    Did you guys have to replace the gasket rings/rubber boot (that connects the manifold pipe to the water box?) or just readjust everything?

  10. #10

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    Okay..It is definitely the exhaust leak.

    It was spraying water out of both sides of the pipe tube (exhaust to muffler) 92191-3986

    On the water box..it looked very corroded at the pipe tube..so not getting a good deal i'd imagine.

    There are two holes on the exhaust pipe that goes into the "3" flex pipe" between the exhaust pipe and the muffler.

    Will try and post pictures soon.
    Last edited by vwmikey99; 07-18-2013 at 08:07 PM.

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