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  1. #1

    Join Date
    Jun 2011
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    Intermitent power loss with warm engine

    The story goes like this: After riding for 30 min to an hour the PWC will experience a smooth, sudden drop in power and just as quickly revs back up to full throttle. It happens in the higher throttle range from 1/2 to full throttle. Sofar the engine has not died during one of these episodes, but if seems like it might. It will continue this cycle of loosing and regaining power every 30 or 40 seconds unless i keep it below half throttle.

    Ive scoured several forums for answers to this tech question. What I have learned is that the problem is not rare, and not restriceted to my make or model. However, I have not found anyone with a real solution

    suggestions that i have seen that dont appear to work are replacing plugs, fuel filters, rebuilding the carb, compression checks, and various others.

    Because the problem doesnt seem rare, Im hoping there is someone around who know exactly what this is


  2. #2
    steve45's Avatar
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    It might be helpful it you'd tell us which model it is.

    Sounds like a fuel venting problem, or a bird's nest in the intake air or something weird.

  3. #3
    Quote Originally Posted by steve45 View Post
    It might be helpful it you'd tell us which model it is.

    Sounds like a fuel venting problem, or a bird's nest in the intake air or something weird.
    Agreed, knowing the model would help.

  4. #4

    Join Date
    Jun 2011
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    Sarasota, Fl
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    2004 Kawasaki stx 900. It doesn't seem restricted to this make or model tho

  5. #5
    There are several things that cause this kind of problem, which is why you won't see a consistent solution. My advice to is start with the simple things and work your way into the more complicated ones. What have YOU specifically tried on this machine?

  6. #6
    I have an 04 stx 900 also acting similar. Mine started off acting like yours, but now it will run excellant for first 10 mins or so when you put it in water. Then will fall on its face like it ran out of gas or something. Feather the throttle and you can get it to go for a little ways and then falls over again. It will die after a couple of times of this. then you can let it sit for 15 mins or so. Will fire right back up and run great for about 100 yards then falls over again. I have messed with it some and had it in 3 different shops. @ of them supposedly rebuilt the carbs and said the other guy didnt. I have replaced all the fuel system lines and filler neck to the tank. Replaced plugs nearly every outing, and replaced wires. I am fed up with the damn thing.
    Time to go trade it in on new yamaha unless someone can help out. Will give it one more chance.

  7. #7
    Quote Originally Posted by pbajeff View Post
    Time to go trade it in on new yamaha unless someone can help out.
    Dang, sounds more like a threat than asking for help!

    Check the fuel pectock assembly for a leak. Actually fuel might be dripping out or air could go into the fuel line causing air lock.

  8. #8
    LOL, guess it could be a threat. I am just fed up with this thing. I have all ready spent enough money on it to of almost paid the difference on a new one. And I have had zero issues with the 2 yamahas that I all ready have.

    All the fuel system has been replaced. It is definitely not leaking gas. I guess there could be a possibility of it sucking air in, but I dont really think so. We have pressured the fuel system checking for leaks - I would think it would of shown up doing this if it was sucking air.

  9. #9

    Ski dying

    Sorta similar to my '97 900 Zxi. Will run fine, doing 40mph and then just die. I am suspecting electrical and have opened the bx and will be cleaning all the wire leads. Had a similar problem on the Yamaha 1200XLT, but it just died one day and would not restart. Bad computer. Replaced that and now runs fine.

    I am thinking I am getting an intermittent signal to the plugs...No spark, no fire.

  10. #10
    steve45's Avatar
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    I bought a used 1100 engine that came with the stator and all accessories. The seller said the engine ran good, but just died. Had good compression, but no spark. He couldn't track down the problem and parted it out. I found the harness to the stator was burned. It apparently had rubbed on the exhaust or something, got hot, and melted the wires together.

    Something to look for.

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