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  1. #1

    Question XL700 Problems Running on Water

    This is my first post; I'm really stuck with a problem with my '99 XL700 and hope there is someone out there able to help.

    I bought the ski 2 summers ago for use on a freshwater lake here in Norfolk (UK, not VA)). It seems to have been well looked after (I doubt that it has ever done more than about 10 hours per year) and ran faultlessly until 2 weeks ago, when engine power suddenly cut whilst in the water (it had previously run well for about an hour), and it managed to limp home about 400 yards to the beach.

    I suspected the fuel system and so have cleaned that right through, the carburettors were in really good condition and look like they have been rebuilt fairly recently (the jets were clear). Having put everything together the ski started quickly on the trailer (connected to a hose), and after adjusting the idle speed ran perfectly well. Whilst running out of the water the engine revs freely, ticks over, the impeller seems fine (I checked the inlet cover and it looks remarkably clean), cooling water exits both from the outlet by the impeller and from the water pilot outlet on the port side.

    All seemed perfect so I tried it out on the water (freshwater lake) only to find the issue remained; the engine will not rev beyond perhaps 2-3000 rmp, but the impeller it providing drive, cooling water is coming out of the pilot outlet and is being discharged vertically from the impeller at the rear of the ski. Everything seems fine, except the engine speed is severely restricted. As soon as the ski is out of the water (on a trailer) it will rev freely (to clear the impeller as normal).

    I suspect the fault may be the overheat warning system mentioned in the operators' manual, but I can't understand why it works perfectly well running on the trailer, connected to a hose, but will not when in the water. I've traced the cooling system through and cant find any blockage (and anyway, water comes out of the pilot outlet both when it is in the water and on the trailer}. The only difference between the two cooling circuits (hose and in the water) is perhaps 3' of hose from the impeller pump to the block (I have blown through that and it seems fine).

    I really cant work out why the motor will run fine on a hose, but not in the water. Does anyone have any ideas? Am I right to suspect the overheat warning system, in which case why doesn't it operate when the ski is on a trailer?

    I'm really stuck, any suggestions would be much appreciated.

    Last edited by othen; 11-03-2014 at 03:21 AM. Reason: typo

  2. #2
    I'm still thinking this problem through, I still can't understand what is going on, but thinking aloud it would seem that either:

    1. The thermo cut out switch is not working, but if this is the case surely it would be defective when the ski is running on the trailer and cooled via a hose? I suppose I could just disconnect the sensor (if I knew where it was, can anyone help me locate it?), then test on the lake again to see if it makes any difference.

    2. The issue only occurs when the ski is in the water, so the impeller is moving some water and so the motor is under some load. This makes little sense as the motor would tend to stall at low speed, however this is not happening, it is just impossible to increase engine speed beyond a fast idle when it is in the water.

    3. Something else I have not thought of is happening.

    Any ideas? I'm stumped.


  3. #3
    gp1200270's Avatar
    Join Date
    Jun 2013
    East Coast
    I would rebuild the carbs.Even if they look good chances are the seals could be bad.Also did you take apart the exhaust pipe the says yamaha on it.I know I picked up some sand one time and it restricted my ski from going over idle.Be sure to take the whole thing apart.There is a few inlet holes that are hard to see.

  4. #4
    Myself's Avatar
    Join Date
    May 2007
    North Central Arkansas
    Check compression first. Might have lost compression in 1 cylinder. Have you tried new spark plugs?

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