I just bought a used 1993 750SS Jet ski. It will not start but backfires and acts like it is out of time? Could the flywheel key be sheared or would a bad coil or ignition module cause this?
Thanks for any info..

 

Mine acted like that for a while; it was spark plugs. At least save yourself some money and try that first.

 

I tried the plugs first, no help. I just bought this jet ski so I do not know much about it. I have been a mechanic all of my life and I am not afraid to take it apart. SO, I took the engine out, took the flywheel off and there it was.. a sheared key. I also noticed someone had taken the bottom part of the crankcase off and I assume they did a ring job on it. I put in a new key, put the engine back in a it fired right up, and sounded great. I only ran it for a few seconds and then I hooked water to the head so I could run it longer. After hooking the water up, the engine would not turn over..BAD. so I took the plugs out and water was coming out of the front spark plug hole REAL BAD!! I unhooked the water, cranked it over and got all of the water out and it started right up again, then I hooked the water up again. (whileit was running) It ran fine but when I shut it off, and took the plug out, in about 20 seconds here comes the water again. Now I have the head off and I assume this is a head gasket problem. I think if someone did a ring job on this engine, then they never put on a new head gasket, or maybe put it on upside down. (They had used red silicone on the crankcase bottom and flywheel cover). I hope I do not have any more problems!! Any particular head gasket to use? I think there are a few different ones available (copper, fiber, ss, etc).

 

not too sure......not too many folks on here with jet skis (that I am aware of anyways) Have you tried any local boat shops to see what they would recommend?

Welcome to the forums! Sounds like you could be our resident expert on water toys!!

 

alright heres the deal. the exhaust on all jetskis is water cooled. when running on a hose you MUST start it then turn on the water if it dies turn the water off right away, and turn the water of b4 you shut the motor off. If you do not do it in this order the unit will hydrolock. this is because the water can run back throu the exhaust and in to the engine since the force of the exhaust is not there to cary the water out.

 

Head Gasket...
Kawi dealer sells one for $31.