Super Jet Haunted Superjet! Please help!

[AnAboveAverageAlternative]

So now that summer is coming, I decided to pull out my '98 and '01 superjet skis and start them up after sitting in the garage for the last 7 or 8 months.
HERE"S THE MYSTERY: After hooking my '01 ski to water, and running for several minutes, I went to turn the water off. I squeezed the throttle a few times to push out any leftover water. After a few seconds, and after releasing the throttle, my ski decided it was going to mysteriously rev up and run at full throttle on its own! The throttle did not appear stuck, I tried pushing the stop button, wouldn't stop...still running, so I pulled the key out....still running at full throttle!!!! Panicked, I ran to turn the water back on for fear of overheating/engine seize. I was going to start pulling fuel lines from the carb (of course, being in the panic mode I was in, I didn't even think to turn off the fuel, but when there's a ghost in your ski, i don't think fuel matters). But after at least 10 or 15 seconds after turning the water back on, the ski started slowing down and eventually shut off.

WHAT JUST HAPPENED??? PLEASE HELP??? I'm scared to start it again or even take it out on the water. Any thoughts would be greatly appreciated!

only thing I can think of is that my fuel tank is very empty. I wondered if there were just fumes left in the tank and the air pressure in the tank was squeezing fuel fumes into the carb. And simultaneously the kill switch stopped working?
What exactly are the mechanics behind the kill switch???

 

[runninAmuck]

when you say it slowly starting slowing down, did it return to idle or just wine down and shut off ? if it wine down and shut off it sounds to me like it seized. ive seized a couple of motors and they sound like what your describimg. for your sake i hope it didnt but one way to find out is to hit the start button. if it just clips theres a prblem. or pull the plugs and see if theres any metal in there

 

[burton148]

http://www.x-h2o.com/threads/111672

Read this.

 

[MarkWalker]

It's called a runaway, air in fuel lines, leak in carb base gaskets. Best thing to do is give it full throttle and hit the kill switch at the same time. Quick compression check, Fill up your tank and go have fun. search runaway motor here on the X, there is a few threads about this.

 

[vrizi]

definately a runaway. I would guess crank seals,... but it could be air coming in from another source. As mentioned above, a handful of wot would have shut the motor off. Hopefully you did not do any seious damage to your motor, but I would guess this scenario,..... The leaking crank seal caused an excessive lean condition causing the runaway and heats up the psiton causing it to continue to burn even after there is no spark from the plug. This condition continued till it melted the piston causing a loss of compresion which then caused the motor to die.

I hope I am wrong,..... good luck

a comp check at this point would tell you if I am right

 

[surfjunkie]

this has happened to me numerous times on different skis and it has never been a tear your engine down scenario. usually been some issue with carbs. not saying it cant be the worse case scenario just saying dont start disassembling your engine right off the bat. check the easy stuff first. fill your tank and go ride see if its better then clean your carbs etc.

also i dont think it revs as high as it sounds. doubt it damaged your motor

i freaked the first time it happened to me also.

 

[Dmac80sc]

That next start up after it has runaway is always nerve racking. It will die if you go wide open throttle and stop button so just be ready. It is possible since the gas tank is just about empty it had some air in the fuel lines so if you fill up the tank you can back it into the water and start it up it shouldn't rev real high like with a load on the pump. That way it can get fuel through the lines then take it out and start it up and see if it runs away again.

 

[Yami-Rider]

My 98 did this to me a few years ago..only had maybe 1/2 a gallon left in the fuel tank and tried starting it....bad idea.

 

[Balduccimoto]

It had nothing to do with the water running or not. It sounds to me that when you were running out of fuel it created a air pocket inside the fuel lines/carb that allowed it to lean out enough where it would create a hot spot inside and keep igniting the fuel regardless of the killer switch. Probably finally stalled when it ran out of gas to diesel with. Fill the gas tank and run it again and see what happens. If it does it again, then you have a problem and riding the ski is not a good idea (it won't runaway in the water bc extra load, but it would still be lean)

If you have a primer, you can also pull the lanyard and pump a bunch of fuel down there to kill the motor.

 

[stefan]

That is scary ass hell happent too me too http://www.youtube.com/watch?v=IZG2DMKACVo hit the throttel and stop att the same time and it will die

 

[schicks]

my ski died on me in the middle of the lake this weekend. Got to shore and put it on the trailer and tried starting it and it ranaway on me. Checking into it more, i found my pulse line fitting popped out where it hooks up to the engine, the nipple fitting came out of the block somehow; which probably caused the ski to quit on the lake and made it runaway on the trailer.

 

[Hi1mjake]

Can this happen while riding it? Or is it just At idle

 

[Balduccimoto]

Can this happen while riding it? Or is it just At idle

While riding it there is too much load on the motor for it to run away. On the trailer there's no load and it actually makes a huge difference. Worst thing to do is go riding with this problem though, as the motor is running lean and detonation will happen

 

[captainx]

hey AnAboveAverageAlternative did you ever get it fixed??

 

[JamesG]

Air leak. it revved up because the spark plugs got red hot and ignited the gas even without a spark. It was smart to turn the water back on because that helped cool the engine and spark plugs so it could turn off.
By spraying starting fluid or carb cleaner around the outside of the engine near the intake, carbs, and crank seal you can locate the air leak. it will rev up a little when you hit the right spot. That's where the air leak will be.

Also, pump the outa your primer if you have one next time this happens. The oil will cool the spark plugs and reduce the "runaway" symptom.