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  1. #1

    Unhappy 1992 750SS Problem, Fuel?

    I recently traded a dirt bike for my first ski, '92 Kawi 750SS. The previous owner had it in a big farm pond. He rode it around the pond and it seemed to run and sound fine. I took it out to a lake for the first time this past weekend and incountered some problems. After launching it the thing ran perfect for about 15-20 minuntes. Then it developed the problem. It will start/idle/run fine however it only runs at about 1/8 throttle just barley moving no matter how much throttle you give it. Overheat light was not on. Continued to run like this the next day after a full night on the trailer. After researching online I have checked a few things. Fuel lines, fuel filters, good spark plugs/spark, butterfly valve in carb opens correctly, new gas, blew in the gas tank check release valve and it only went one way, However there was quite a bit of resistance is this normal? I pulled the water temp. switch and plan to test it tomorrow. It was not clogged but like I said I plan on testing it in water on the stove per the manual. I have not checked the carb yet could that be part of the problem? One more thing, should the fuel seperator/sediment bowl have a foam filter of some sort as mine doesn't. Any advice, tips, or encouragement are greatly wanted and needed. Thanks Justin

  2. #2
    Welcome to the Hulk Justin! The vent leading off of the gas tank is actually a check vavle. It's purpose is to allow air in and stop splashing fuel from leaving the tank. Sometimes they will seal too well and prevent the tank from getting air and the tank will implode. That will cause the ski to run at only about 1/8th throttle. An easy way to check if that check valve is a or the problem, when you run the ski and it starts to bog down, come to a stop and crack open the fuel cap...give it a few seconds and try again. If it comes back to power then the check valve is defective.

    If you have no idea what kind of condition the carbs are in, then pull them off and give them a good cleaning. The check valve does happen, but not very often. My guess would be carburetion before anything else. It never hurts to give the carbs a cleaning. The fuel filter you speak it the clear platic bowl with 2 or 3 lines running to it? If so it's a fuel separator or sediment bowl. It should only have a screen inside to stop sediment from carrying on into the carbs.

    One other thing you can and really should do is take the plug caps off of the plugs. Pull the caps off of the high tension leads (plug wires) and cut off about a 1/4 of an inch from them. Re-install the caps and really secure them well with a good zip-tie. That may even be your problem right now. Those wires will back out away from the threaded post in the cap and you will drop a cylinder giving the bog effect. That will also only let the engine run at about an 1/8th throttle regardless of how much you open it up. Give the plug leads and tank test a try first...they're the easiest to do and may be all that's wrong. Let us know how you made out.

    **Quick addition** Clean out that fuel separator too. It also will prevent water from getting past it but if it fills up too much eventually the water will be picked up with the fuel and get stuck in the carbs. Water doesn't like being forced through jetting ports so it just stops fuel flow entirely. That too will put the kybosh to your fun.
    Last edited by Schwarzenegger; 08-27-2008 at 05:39 PM.

  3. #3
    Thanks for the quick response. The fuel filters I checked were the ones in the tank itself. My fuel sediment bowl doesn't have a screen of any type in it though. With the check valve I don't think its that because while I never took off the tank cap when on the water I did check for a vaccum in the tank with it on trailer and put it pack in the water the next day with the same problem. My main question on that was more or less how much resistance the check valve should have as mine has quite a bit. As for the spark plug wires they are currently zip tied on now. When I checked the plugs and spark the wire did back out of the cap on the rear cylinder, however that was on trailer and I strongly reiserted it and tested it the next day aswell with no such luck. I don't know if or how much the wires have been in the past, roughly how long should the two be in cut or non-cut form? One last addition is that the fuel sediment bowl is clean but as I said does not have a sceen on/in it. As much as I didn't want to I know that I should've and need to clean out the carb, maybe I'll start that tonight, wish me luck as I hate carbs thats why I have a Suzuki LT-R450 EFI quad. Thanks for the info.

  4. #4

    Join Date
    Jul 2008
    Orange County, NY
    I just had the canister apart on my 94 yesterday and it had no screen in it. The ski was just bought from the original (female) owner and I'm very confident that is the way it left the factory. If you look at an online parts lookup for Kawi parts the diagram shows no screen in there. Check my post from the other day for a picture of what it is supposed to look like. I had a dying problem with mine when we took it out the other day and when I got home I found the top of the tank pretty well sucked in. I'm assuming that was the problem and I have blown out all of the vent hoses under the hood. I haven't had a chance to confirm my repair because the weather hasn't co-operated.


  5. #5
    Well I think I might have just solved my problem or at least part of it. I just finished testing my water temp. switch as the repair manual said. It says to put the switch in a pot of water on the stove with a temp. gauge. Hooked up the ohmeter like they said. The ohmeter should read infinity when below 203 degrees and read .05 when over 203. Then when the water cools down to below 190 the ohmeter should return to an infinite reading. With the cool water the ohmeter read nothing, once over 203 degrees it still read nothing. All this means that the switch is faulty, right? Also if in fact it is faulty how can I tell if its the actual switch that is faulty or if its the wiring going from the switch to the electric box? As the switch is $73.00 and the Wiring is $85.00 I would greatly perfer to only by the faulty section and not a completely new switch/wiring. Can in bypass the water lines and leave the switch unpluged from the electric box to further insure thats the problem before spending $$$ on a new switch, College student/flight lessons to become a commercial pilot have left me on somewhat of a tight budget. Thanks

  6. #6
    I would make sure u didnt suck anything up in the impeller. A Compression check wouldnt hurt either.

  7. #7

    Join Date
    Jul 2008
    Orange County, NY
    If I'm reading your post properly, when the sensor sees over heat (i.e. over 203*) it should short out and when it drops below overheat (i.e. 190*) it should go back to an open circuit. If yours is always reading open, it is NEVER seeing an overheat condition and as far as the ignition system knows all is well. I'm not saying that you don't have a problem with the sensor but if the sensor is always showing an open circuit (no overheat) then it isn't causing the ski to go into any sort of "limp mode". Did you get the water to boil during the sensor test? I don't know how you were determining the temperature of the water but if it is boiling it is definitely above 203* and that will be the best way to test it IMHO. If you are still getting a faulty reading from that sensor, then the sensor is the problem, not the wiring going to it. Even then, I think you might have some other problem since the sensor is just telling the electronics in the rest of the ski that all is well no matter how hard you overheat it. Basically, based on your tests, according to the temp sensor, it should just run great until it cooks itself. Take it out and if it does it again, loosen the fuel filler cap, if you hear a "swoosh" of air rushing into the tank, you've probably got a situation that isn't allowing air back into the tank. I'll probably have mine out this Sunday and if it acts up again I'll temporarily disconnect the vent hose to see if it clears the problem up.


  8. #8
    Correct, Just unplug the heat sensor and you can eliminate that as a problem.

  9. #9
    Check to see if fuel is flowing to carbs.

    1. pull off both fuel in line and return line
    2. Blow in the return line to pressurize the gas tank and quickly put your thumb over the the return line.
    3. Fuel should flow out of the in line.

    Dont confuse any lines with the pulse line just leave it alone..

  10. #10
    You were asking about how hard it was to get air past that check valve and I apologize for forgetting to mention that. It shouldn't be hard at all, you should be able to blow through it almost as easily as blowing through a straw. That valve could just be on backwards. Take it off and try to blow through both sides...if you can get air through the side going away from the tank fairly easily, then turn it around and try the ski again. Also if you can, get us some pics of the plugs please? That will tell so much more and save on a lot of guessing.

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