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  1. #1

    94 Kawasaki 750 Xi overheating while in the water

    I have a 94 750 Xi that keeps overheating as soon as I put it in the water. It runs cool on the hose but instantly overheats in the water. There is a steady stream coming out of the pisser, but the water is really hot coming out of there when in the water. None of the hoses are obstructed, I've checked and blown them out and I have taken the exhaust off as well, no obstruction there either. I recently replaced the jet pump and still the same issue.

    Anybody got any ideas? Help!! Could the water box be obstructed? That the only thing I haven't taken apart yet. What am I missing? Note I run it mostly in salt water but always flush it after every use.

    Does anybody know what the operating temp should be?

    Perplexed


  2. #2
    splashman's Avatar
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    Check for clog in oil lines and cooling water line. Also, when enough carbon has built up in the combustion chamber it will cause overheating. If no luck after checking the above, It is most likely calcium deposits built up in the ports of the engine. Running in salt water takes it's toll regardless of flushing after use.

  3. #3
    splashman's Avatar
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    Forgot to answer your Q: The temp sensor turns on 190 degrees and at 203 degrees will cut full spark while running which means get ashore and check your cooling system. Dont have answer to operating temp but definitely under 190 degrees

  4. #4
    Thank you. I run it on premix, so oil lines are not an issue. I thought it might be that white calcium salt buildup blocking some of the engine ports but I took it apart again this morning and I couldn't find much build up at all. I think it has something to do with the jet pump, even though I changed it with a new "used" one I don't think it is pumping enough water to cool the engine. I took the pump out again and with an adapter I attached my garden hose to the direct line that comes off the pump and ran the engine and she was cool as can be. Therefore the water seems to be circulating through the engine ok. I'm going to change the impeller on the pump and try it in the water again. If it still over heats - then I'm totally stumped. I'll let you know how it turns out, thanks for your help.

  5. #5
    splashman's Avatar
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    please do as i am interested in what you find. I just checked the troubleshooting chart for overheating and there are only three possible causes on the list that we have not already covered and they are clogged flame arrester, carb not adjusted and wrong oil or fuel being used. Good Luck

  6. #6
    I put a new impeller in the jet pump and she now runs much cooler. The impeller to housing clearance on the old pump was double the normal wear limit. With the new impeller it's within spec; had a nice tight fit. Water out of the pisser is no longer burning hot. I can put my foot in the stream and it's hot, but not burning, like hot bath water. Even though the old pump was working and the ski was moving through the water OK, it wasn't pumping enough water to cool the engine. I still have some other issues to work through, but at least it's not over heating.

    I think this is a common problem for the older Kawi's, I had two engines failed on two separate jet skis both 750's within a week of each other. Both I thought were do to oil pump failure, but now I'm 99% sure it was due to overheating caused by jet pump impeller/liner wear.

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