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  1. #1

    STX-15F Power issue

    I took my 2006 stx-15f out for the first time this weekend. It seemed to have an issue where when I would first accelerate it would take some time, almost felt like something had been sucked into the impellar, but after a few seconds it would get up to full speed.

    After cruising for a minute or so the performance would drop to a top speed of around 48 MPH almost like one cylinder wasn't firing. I would keep it at full throttle and would get occasional busts up to top speed (around 62) but usually after hitting a wave it would drop back to 48 or so. It seemed like after I would slow down and punch it it would go back to full speed only to drop down after a minute or so.

    I had no waring lights and no trouble starting the engine after I would turn it off. I changed the oil and battery before I went out.

    My question is do you think it could just be a fouled plug. I took them out when I got home and they looked fine, although I have 240 hours on the original plugs. Also the gas is the same from last fall, I only topped it off with about 4 gallons of gas before I went out.

    Any thoughts on what the problem may be?


  2. #2
    jetskr's Avatar
    Join Date
    Jul 2005
    Beaumont, Texas
    I would get the all of the old gas out and replace with new and certainly change the spark plugs. Your problems sound like what fouled plugs would make a ski do. Remove the filler tube from the gas tank to get a syphon hose to go down into the tank, its almost impossible to do it with it on. good luck.

  3. #3
    Where was the rpm at when it dropped power, maybe the thing is coming unhooked with the water or you have a coil, injector, fuel delivery problem? Could be a spark plug too.


  4. #4
    No drop in engine rpm's. I don't think it was coming unhooked from the water, it would also happen on flat water, I am going to drain the gas and change the plugs and see what happens. Thanks

  5. #5
    So if the rpm didn't drop then engine power was available, it just wasn't coming out the big hose. If that is the case it may well be pump cavitation.Two things will cause the top speed to drop-a loss of rpm or a loss of pump output/efficency.

  6. #6
    If that is the case, pump cavitation, would I need to replace the pump?

  7. #7
    Maybe the ride plate is not sealed to the hull, intake grate and/or pump correctly. That's the first place I'd work on for the simple reason that sometimes you get top speed and sometimes you don't at the same engine rpm. Cavitation will eventually burn material from the impeller blades. Quickly look up its ass as best you can and check the blades and the gap around the impeller tips for obvious defects before removing ride plate and grate for resealing using RTV.


    Pumps can be rebuilt, it's a matter of knowing where the wear is on the impeller, pump casing or both. Not sure if anyone makes sleeves for the pump and will machine casing or not. Some of the guys in here will know maybe.


  8. #8

    Join Date
    Mar 2008
    Well I think i would start with the simple things first... drain the fuel and replace the plugs, and add sea foam to the fuel, to take care of what is in the fuel rail. Take it out and run it .. it might be possible you have a injector trying to quit on you or have one that is stopped up. You can go to a local parts house and tell them you need a noid light and find out if all your injectors are firing, the noid light should flash rapidly, almost a steady light at times When the engine is running on the hose.
    If there is no improvement then go after the more labor intensive stuff.
    thats just a suggestion.It doesn't sound like a pump problem and a stopped up injector might or might not give you a light or a code. You can remove the plug wires and see if you have any burn marks on the outside(a white looking burn line on the shaft of the plug wire). if so replace them when you replace the plugs.
    Last edited by STX-15FER; 05-07-2009 at 06:29 PM. Reason: typo

  9. #9
    I drained the gas, filled up with fresh gas, poured in a bottle of injector cleaner and changed the spark plugs. I did the test on the injectors that it said to do in the service manual, hold a screwdriver to the injectors while the engine is running and make sure you here clicks. I heard all injectors clicking.

    I ran it on the hose for awhile it seems ok but did sort of bog when I applied full throttle to it. That brings me to another question, how long can you run it on a hose and is applying throttle ok?

    I looked underneath and the intake gate had a couple of chips out of it, nothing major though and it was sealed solid. I will take it out and ride today and report back. thanks

  10. #10
    Draining the gas and changing the plugs was the answer, it is running great, as strong as I can remember and it has 260 hours on it.

    I have changed the oil, and lubed cables every 20 hours or so on it, other than that really nothing else. What other maintenance do you think is vital at this point, oh I also replaced the battery before this summer.

    Thanks a lot.

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