I have a 1996 STS 750 jet ski with a problem I can't figure out, please help. here's the story. last year it ran great, no problems at all, this year when I took it out the first time after about 10 minutes of riding full throtle (9,000 rpm) the rubber exhausttube between the wet and dry muffler burned a hole in it. I flushed the water system installed new tube and tried again, the same thing happened. took to dealer and they found a rock in the system (at the valve?) anyway said it was fixed. Took the ski out this weekend and now have a new problem??? First the ski ran great for 10 minutes then would only goto 3,500 rpm. it runs great upto 3,500 then the power cut off like a rev limiter. also the water coming out of the side over flow is really hot, I only remember it being warm in the past. after the ski sat for a while we took it back out, this time it ran for two hours before it happened again. any help would be appreciated. also installed new stock spark plugs....
Thanks,
Ken

 

I'll take a guess as a mechanically-inclined person. Admittedly, I'm not the smartest guy on here when it comes to these...

I am about 90% sure that your kawasaki has a temperature probe on the engine (probably in the cylinder head). If the temperature gets above a certain value, the engine speed will be limited to prevent severe engine damage. I'm guessing that is what's happening - your engine is overheating, and the temperature probe is setting-off this safety feature. (Geez, I hope I'm right on this... hopefully somebody can confirm).

So, what could be causing your engine to overheat? Lots of possible answers here:

1. The mechanic didn't find all of the rocks in the cooling system. Maybe a rock is in the cylinder block, another hose,or somewhere else?
2. The clamps that hold the cooling hose to the jet are missing or loose, or the hose coming from the jet has a split.
3. The head gasket is leaking (due to bad re-assembly, need to re-torque head nuts, or warped cylinder head) and allowing exhaust gas to get into the cooling system.
5. There is lots of sludge, sand, debris, etc. in the engine block and cooling lines that is restricting the flow of water through the engine.
6. The temperature sensor is bad and fooling the jet ski into thinking that it's overheating when it's actually not (probably not the case if the water coming from the bypass is hot).
7. Something else that I'm not thinking of right now...

Usually, the simplest/most obvious answer is the correct answer. Check the cooling hoses for weeds/debris, rocks, and other bad stuff. See if a friend can help blow them out with compressed air or a garden hose. Pay particular attention to the hose that comes from the jet pump back to the hull - maybe it's loose or damaged?

Hope this helps...
Mike

 

Thanks, that gives me some things to look at. I'll let you know what happens....

~Ken