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  1. #1

    Yamaha XL1200 Runaway Engine with lanyard pulled and stop button pushed didnt stop!!

    all weekend we rode my 98 yami xl1200(premix converted) at the lake with no problems, friday saturday sunday and monday...we had a blast.............well last night when I loaded up the ski,I turned it on to clear any remaining water in the engine and noticed it was reving higher than normal, so i pushed the stop button and the engine didnt cut off ........so I pulled the safety lanyard and the engine was still running........so i wot'd it and it cut off.......I read on line that an engine airleak will cause this, also the carbs will do this as well........the engine has new seals and the carbs are rebuilt with new gaskets...........is there anyway to pin point the exact problem without ripping every thing apart?


  2. #2
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    if the fuel tank is near dry, that can casue a runaway also.

    You can pressure test the fuel system to see if it is leaking. a leak at the selector can let air into the lines.

    pulling the choke will sometimes kill a runaway before it flies apart. Other times you have to physically block the air intake

  3. #3
    Quote Originally Posted by nmpeter View Post
    if the fuel tank is near dry, that can casue a runaway also.

    You can pressure test the fuel system to see if it is leaking. a leak at the selector can let air into the lines.

    pulling the choke will sometimes kill a runaway before it flies apart. Other times you have to physically block the air intake
    The tank has about a gallon of fuel in it.....would this be the cause? I just ran it on the flush kit about 5 minutes ago and it did the same thing,would not cut off with the stop switch or lanyard...........wot'd it to cut it off........tried it again and the stopl switch worked this time but it still revs up high...why would low fuel cause it to rev so high??

  4. #4
    Ski Hacks MG's Avatar
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    Runaway is caused by air leak among other things like fuel switch being in the "OFF" position, etc. The reason it continues to run after you pull the lanyard is because it is still catching enough spark off the hot carbon deposits in the cylinder so even yanking the plug wires will not shut it off a lot of the time. WOT or choke is the ticket. Check all vacuum lines also.

  5. #5
    Quote Originally Posted by CCW View Post
    Runaway is caused by air leak among other things like fuel switch being in the "OFF" position, etc. The reason it continues to run after you pull the lanyard is because it is still catching enough spark off the hot carbon deposits in the cylinder so even yanking the plug wires will not shut it off a lot of the time. WOT or choke is the ticket. Check all vacuum lines also.
    The pulse lines are nice and tight,as well as all the carb lines............is there any other lines to look for?I do not want to distroy this engine if there is an underlying issue.....

  6. #6

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    What is your in water idle set at? I have had this issue on a fresh rebuild because the idle was too high, same result on land as an air leak. Runaway.

  7. #7
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    Quote Originally Posted by DanielDucati View Post
    Quote Originally Posted by nmpeter View Post
    if the fuel tank is near dry, that can casue a runaway also.

    You can pressure test the fuel system to see if it is leaking. a leak at the selector can let air into the lines.

    pulling the choke will sometimes kill a runaway before it flies apart. Other times you have to physically block the air intake
    The tank has about a gallon of fuel in it.....would this be the cause? I just ran it on the flush kit about 5 minutes ago and it did the same thing,would not cut off with the stop switch or lanyard...........wot'd it to cut it off........tried it again and the stopl switch worked this time but it still revs up high...why would low fuel cause it to rev so high??
    the fuel pickup, when the fuel is that low will be sucking up air as that gallon of gas sloshes around inside the tank. This creates a lean condition.

    Tigershark skis have a warning sticker for this type of lean condition. Engine seizure and no warranty is mentioned.

    Might have to add this sticker to my other infamous one about a water injection injury.

    In any case, keep engine screaming to bare minimums till you can nail the problem..putting five in the tank would likely be the cheapest and quickest way to deal with this thing.

  8. #8
    Quote Originally Posted by LT1GMC View Post
    What is your in water idle set at? I have had this issue on a fresh rebuild because the Idle was too high, same result on land as an air leak. Runaway.
    after taking the carbs off and the exhaust to do a air leak test on the engine ,I found no air leaks.........got it back together and took it to canyon lake and adjusted the idle on the water and that was the culprit......idle was set to high............also i took my gps out with me and at wot garmin nuvi 500 gps read 64 mph but the digital guage on the ski was reading 73mph......someone mentioned how to adjust the speedo on the ski by using a file to file down some tabs but where are the speedo tabs located? I would like to get the speedo guage as close as possible to the accurate speed......

  9. #9
    Yamaha artisan Cutlass's Avatar
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    Quote Originally Posted by DanielDucati View Post
    someone mentioned how to adjust the speedo on the ski by using a file to file down some tabs but where are the speedo tabs located? I would like to get the speedo guage as close as possible to the accurate speed......
    Don't bother. It'll never be right.

  10. #10
    Ski Hacks MG's Avatar
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    Quote Originally Posted by DanielDucati View Post
    Quote Originally Posted by LT1GMC View Post
    What is your in water idle set at? I have had this issue on a fresh rebuild because the Idle was too high, same result on land as an air leak. Runaway.
    after taking the carbs off and the exhaust to do a air leak test on the engine ,I found no air leaks.........got it back together and took it to canyon lake and adjusted the idle on the water and that was the culprit......idle was set to high............also i took my gps out with me and at wot garmin nuvi 500 gps read 64 mph but the digital guage on the ski was reading 73mph......someone mentioned how to adjust the speedo on the ski by using a file to file down some tabs but where are the speedo tabs located? I would like to get the speedo guage as close as possible to the accurate speed......
    The speedometer wheel is on the left rear of the ride plate and has (4) phillips head screws holding it on and a black cable running to it.

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