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  1. #1

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    STX15F wont idle and engine seems tight.

    First of all, thank you in advance for any help you may give me. I appreciate the opportunity to ask questions and get the benefit of the knowledge of everybody here.
    My STX 15F is sick. Here are the issues. This first started with the ski running perfectly until it got fully warmed up. Then, as long as you were on the gas, all was well. But, if you let off of the gas fast, it would die. Sometimes it would start right back up and other times, it wouldn't. The times when it wouldn't start back up it acted like it was really hard to crank. If I tried more than a couple times, I would get the battery low alarm and it seemed like it took everything the battery had.
    I put a new battery in it and checked all of the connections. All ok. Same issue. The spark plugs are brand new. I took it to a so called "PWC Shop" and they said it needed an idle control assembly. They installed it and same problem. ($380) It sat there for another month and I finally went and got it. The guy admitted that he just didn't have time to check it out fully. It sat outside the entire time without the cover on it and when I got it home, there was water in the gauge cluster and it was dead. I faulted myself for that because I didn't ask how the ski would be stored when it was not being worked on. So, new gauge($875). And problems remain.
    Took it to a reputable Kawasaki dealer here in South Florida and paid them to diagnose the problem. The technician took it out for a ride. He rode it for about 20 minutes and he said it died and wouldn't restart. Towed it to shore.(I don't know how fast, probable over the 5mph that its supposed to be towed at. He said he took the spark plugs out and 2 cylinders had water in them. He blew them out and said it still wont start. They called me and wanted another $300 to tear into the engine for further diagnosis. I went and got it instead. They said that they think the engine is tight.
    I got it home and charged the nearly dead battery. I took the plugs out and cranked it. It seems to crank fine and I didn't see any water. I put the plugs back in and it seems harder to crank over now than it used to be. I decided to remove the jet pump to see if it may have a tight bearing. Its ok. No problem. I can actually start the engine now but when I let up on it, it dies like it has a load on it.
    My question now is, how can I tell if the engine is actually tight? I cant turn the pto shaft by hand and I have not put a wrench on it to try to turn it over. How hard should it be to turn with everything removed and spark plugs out?
    Also, if anyone has had a similar issue, what was your resolution? Thank you again for any help. Sorry about the long post.


  2. #2
    Take the time to smile sirbreaksalot's Avatar
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    Welcome to the forum..

    but in future try and post general questions in the OPEN DISCUSSION section.
    this section is supposed to only be 4 STROKE PERFORMANCE
    not repairs or help line type questions.

    by posting in appropriate section , it allows the search feature to work way better.

  3. #3
    steve45's Avatar
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    Welcome ab!oard, renneka!

    Sorry to hear you're having problems and especially that you've managed to find a couple of incompetent shops.

    Has anyone actually done a compression test? It sounds to me like you may have a scored cylinder or something like that. When the engine heats up, clearances get smaller and can give symptoms like that.

    I'm surprised that water got into your display when it wasn't submerged. I seal the plug on the back of my displays with 3M 5200 Fast Cure to keep water out, but I've only experienced trouble when a 'Ski has been flipped. Of course, leaving it exposed to heat/UV rays will cause the display to turn black.

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  5. #4

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    I actually had a hard time figuring out how to start a new post. I couldn't get the button for adding a new post to show up anywhere except this thread. Sorry. The water got in because there was a small crack in the material covering one of the softkeys. For all I know, it may have been being sprayed with a sprinkler head every day for a month. I'm just not sure. That's all I could figure because everything else was sealed well. As far as compressions, they are all between 160 and 170.
    Should I be able to turn the engine over by gripping the pto and turning? I need to know if the engine is tight.
    Thanks again.

  6. #5
    With all the spark plugs out the engine should turn over by hand relatively easily. There will always be some resistance when the pistons reach TDC but there should be no binding or unusual noises. Iknow you said you've checked the pump bearings but I'd remove the pump again and check the engine's free spin. Perhaps there's a possibility the pump bearings are getting hot and siezing.

  7. #6
    SplishSplash's Avatar
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    Are you sure there is no back and for motion in the pump? Is the impeller on tight?
    I would buy a new oil filter, remove the old one and cut it open, see if it is full of metal shavings. If so, a beating might have failed.
    You can remove the pump and back the drive shaft up to dissengauge it, See if it starts and idles correctly then.

  8. #7

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    The pump is still off. The impeller has a little side to side play but not enough to let it hit the housing. No front to back play. The pto shaft running from the engine to the pump has a coupling with a spider type rubber insert. I can grab the end of the shaft and pull it about a half inch towards the back of the ski. This actually moves the rear part of the coupling away from the engine and it almost moves far enough that I can almost get the rubber spider out of the coupling. Not quite though. The shaft is able to move back and forth in the bearing. It looks like I need to move the engine forward though in order to have enough room to get the coupling apart and the spider removed.
    Grabbing the coupling by hand and trying to rotate the engine isn't working out. It is still tight even though I can get a pretty decent grip on the coupling. Ive made the decision to pull the engine. Im pretty convinced that something is tight in it. I am going to work on it as I have time. Right now, I have most of the hoses disconnected and labeled. Also, the battery is disconnected. The air filter box and the muffler are removed. Im very hopeful that it is just a scored cylinder or something on the top end. If its crank bearings, I may be looking at an engine swap. The oil looks perfect. Almost clear to look at. No discoloration like I would expect if I had a bottom end problem. I will cut the oil filter and inspect it for shavings once I get the engine out. This may take a few days because I am busy this weekend and wont have much time to work on it. Thanks for the help so far. Its appreciated.

  9. #8
    Pain is fear leaving your body.... rlovebk's Avatar
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    First of all this is a 4 stroke so even with plugs out it is difficult to turn by hand. You are also rotating 2 cam shafts and depressing springs and valves, even oil pump.
    Install the pump. Put a little water proof grease on the spline shaft. You do not have to install everything just the pump and 4 bolts, and the cooling hoses. I do not suggest turning the ski over without the pump installed and the closeness of fitment does not usually allow you to push the impeller shaft back enough to completely disengage. Make sure your pump bearings are good. This is vital.
    I saw water in engine comment - pull all of the oil out of it immediately. If there is any sign of water intrusion change the oil and filter.
    Is there any sign of rust on your plugs? Do a compression check.
    Do you have spark?
    Check fuel pump pressure.
    Does it turn over and do you here a strange electric noise cycling (this is normal, throttle/idle sound) when you turn the key on and off?
    I would do these things before removing engine as you may or may not need to.
    Checking for end play on the crank - this can be done with engine in the ski. Get a pry bar and gently push against block trying to move engine coupling away from the block. DO NOT apply much pressure. Just enough to determine if it moves or not. 1/4" is too much. That' mean bottom end is toast. Do the same gently pushing towards the block.
    How many hours on this ski?
    Let us know what you find.

  10. #9
    Pain is fear leaving your body.... rlovebk's Avatar
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    Woops just saw your oil comment. But if water was in the engine it would be hard to not have any in the oil. I wander if your exhaust hose fitting where it connect on the collector pipe is corroded? This can eat into the exhaust side (vs. cooling) and cause it to not want to idle as it allows water into the combustion chamber areas.

  11. #10

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    Oct 2018
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    rlovebk,
    Thank you very much for the comments. I do hear the clicking noise after I turn the key off and on. Where can I check fuel pressure and what is normal psi? The plugs are new so they wont (and dont) show any rust. However, the plugs that I removed a few months ago had a couple of them showing some rust. I kind of discounted the water in the cylinders because I figured the Kawasaki dealer towed it too fast and allowed water intrusion but you may be on to the actual problem I was busy this weekend and wasn't able to work on it. Im going to play with it some today. Im not a mechanic but I have worked on my share of engines in my life. In my experience the color(and smell) of the oil has always been something that I relied upon to determine major engine problems. Or not. This thing has oil that looks like it was just poured into it. No discoloration or smell other than what you would experience from brand new oil. I will check the play of the crank and report back. I still think something is binding somehow external to the engine. I was actually disappointed when the pump turned over freely. I was hoping this would be a easier diagnosis. I think it had about 300 hours on it. I had to replace the cluster so now it doesn't show the true time. Compression's are as follows: #1-160, #2-165, #3-155, #4-160.

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