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Hello. I have a 1997 GP 760. On Sunday, it was running great. I took an hour break, and then went to go back out. My uncoordinated friend and I tipped it 4 or 5 times trying to get on, rolling it both directions. It quickly righted itself every time, but must have taken on some water. After that, I had a terrible time getting it started, and staying running. Once it did stay running, it had no power, it would move, but not get on plane. Yesterday, I took it back to the water, and it started nicely, held an idle, but still no power. It was better, as it would get on plane, but no power out of the hole, or top end speed. I'm thinking that it might have gotten water where it shouldn't have??? Any other ideas, any quick fixes?

Thanks.
 

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The fuel system is pretty well sealed..so you can more or less exclude that..

That leaves you with the ignition..and..mechanical..

Pull the plugs and see what they look like..black and soot can mean a miss-fire(rich)..

If a plug does look fouled..follow its wire up to the coil (it will be under a water-tight cover)..does anything look "rusted" or wet?..water in here will short out a coil and make you drop a cyl...
 

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Discussion Starter #3
One plug seems much more soiled than the other. Is changing the plugs the solution, or do I need to do something else as well??
It starts fine, but won't give over 5000 RPM.
 

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Replacing that plug MAY make it run properly again...

But the cause has not been discovered..

Maybe that plug was a little "off" from the start..if so..swapping it out will fix it..

But..if the problem comes back..then you need to look further into it..
 

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Discussion Starter #5
Thanks Tymeshare. I changed the plugs and it ran fine for about 15 minutes - had it up to its top end very nicely. Then the RPM's began to fluctuate from 5000 to 8000 and back. Then eventually only 5000, as it was only running on 1 cylinder again.

After I took it back home, it will run on the front cylinder, but not the back. The back cylinder has spark. Switching the spark plugs from front to back didn't make a difference, because without the plug wire hooked up on the front cylinder, it would not start with only the back (I'm not sure if that is maybe a normal, timing thing, or if that is my problem!).

I took the electrical box apart, and everything seems dry in there.

What would be the next thing to look for?

Also, how do you hook up a garden hose to let it run on land? My unit only has a plug hole that isn't the same size/thread as a garden hose????
 

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I think i would be looking into doing a little testing on the ignition..

I am not sure i am qualified to tell you exactlly where to look on your particular ski..but..

First thing would be to see if the coil that leads to the affected cyl. is recieving a 12v signal..take volt ohm meter..go from batt neg. side to coil..whats it say?(power on of course)..

If the coil shows a signal(12v)..reomove coil high tension lead(plug wire) from coil and switch ohm meter to "ohms"..whats it say?..write it down and look in tech forum for a factory spec..(i have no idea what yamaha set as a resiestance..or if it even has a reseistor in the wire)

If its a little off of that factory spec its ok(0.1 off tops)..those specs are more of an average then a mandate..

If the wire is ok then you now need to check the ign modules and crank trigger..and I fear that if you have not done that before then it may be above your skill level(sorry..not meaning to judge here)..

Aside from that..you might be looking at a mechanical screw-up..ie. rings, piston, reeds/cage or other..a good bore scope helps with this kind of inspection..it allows you to see inside combustion chamber and inspect reeds without breaking the seal of any of these parts..
 
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