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  1. #1

    STX 15F Engine Running Problems

    Hey all, I am having problems with my 2008 STX 15F with only 19 hours. First problem is that it just doesn't seem to have the get up power or top end speed anymore. I changed the spark plugs and put sea foam in the gas. The hesitation wasn't as bad but it still didnt seem right. The second problem is the it sounds like it has a rattle coming from the drive shaft/impeller area. The impeller is a little nicked up but doesn't seem too bad. Any suggestion as to what the problems could be I would love the help. Thank You!

  2. #2


    Hey Rich1985


    I have seen many of these same situations come through my shop. There are a couple of things you need to look at, to determine which way we are going to tackle the situation.

    Step 1 : We need to check to see if the pump bearing has not done itself in - a common problem with Kawa's. What happens is the bearing fails, and transfers all of the thrust onto the crankshaft of the engine. Have you had the "Oil overheat" alarm going off? If the bearing has gone and the alarm has gone off, then you need a new engine. This can happen at any hour frame, as it is a defect in some bearings and wear and tear in others. Pull the pump housing off the back. Not hard to do, and it only takes me about 10mins now. Go slowly and watch where all of the parts come from. The ride plate must also come off. Once all of the bolts are undone, you will need to pry the housing out of place. It gets a bit stuck in there. Check to see if the impellor is still tightly in place, but can still spin easily and freely without touching the side. If this is so, I would suspect that you have lost some of the spline on the shaft or impellor, and that is what is causing the rattling. This normally only rattles when it is out of the water. If the impellor falls out of the housing or is wobbly, go and sit in a corner. Then scream. Then cry...

    Step 2 : Tell us the verdict...

    Good luck mate...

  3. #3
    Mine has always rattled out of the water, however after greasing the splines and installing a new shaft boot the tinging or pinging (like a tuning fork) is gone for now due to grease cushioning (it will be back). Most all skis make this noise since the impeller is not loaded into the shaft splines by the water. I have heard a noise in the aft hull from time to time on many machines including the 15F at idle and is gone slightly above. A low frequency vib resonating through the hull, this again is normal when in the water. Top speed should be 58-63mph indicated and it should have similar acceleration as when new. Sometimes after we ride the same shit for a while it appears slower when in fact we have adapted to the newer excitement level-that is what the ocean waves are for 19 hours is dick for a pump and I highly doubt the bearings are at fault as this is a low thrust application compared to say a blown machine like a 250 or 260. Anyway best to check it out for your own peace of mind as per Coastben suggestion.

  4. #4
    Hey thanks for the help. I will look into it and let ya know what I find. Thanks again

  5. #5
    nicjak's Avatar
    Join Date
    Mar 2008
    Warragul, Downunder
    dont go overboard stressing with the first response i put my money on your prop if it has dings more than likely thats where you have lost your speed. im guessing the hesitation you speak of is actually cavitation

  6. #6

    Join Date
    Mar 2008
    +1 nicjak

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