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Hi and thank you for your question.
After the 10 minutes, what happens if you try to rev it up? Does it stall right away or does it just cough and sputter or just not build any revs whatsoever?
Did it affect the way the ski ran, as in, did it help?
Thank you again.
What we need to determine is whether it is losing spark, fuel or has a mechanical issue. The best place to start is a compression test. Let's check that out and make sure the engine isn't hurt. Your symptoms could be an indication of a mechanical issue.
Next, if the compression is ok, put a timing light on the spark plug leads and see if it is getting spark when it won't start or loses spark when it wants to quit.
Let me know what you find and we can go from there.
Then you have a fuel supply problem. Btw, what was wrong with the one way (aka roll over valve) valve? When it dies, if you squeeze the primer bulb, is it hard like there is fuel in it or does it feel like it has been sucked dry?
Thank you for the additional information.
In an indirect way, rebuilding the carb could very well be the solution. I suspect there is a problem inside the carb, so by taking it apart to re-build it there is a very high possibility that the root cause of the problem will be discovered. I think taking the carb apart at this point is a good idea.
I don't know what symptoms you would be having with a one way valve that flowed both ways as far as running problems. The only problem it could create would be to allow fuel to drain out of the tank if the ski were upside down. Running wise, it should not make a difference. Was it?
I can get you set up with the settings on the fuel screws.
The base settings are 5/8 turn out from lightly seated on the low speed screw,
1 turn out from lightly seated on the high speed screw.
That should get you going!
The easiest way to check spark is to pull a spark plug out of the head, put it back in the cap and lay it on the head but away from the open hole and crank the engine over and look for spark.
If you are getting spark, double check your fuel supply and return lines. The fuel supply line goes on the bottom fitting, the return line goes on the top. I know that seems counter-intuitive, but it is correct.
Let me know how it goes.
Thanks for the pics.
You are absolutely correct. That is water on the plugs. Now the question becomes where is the water coming from? Are you running the ski on the hose/flush kit? If you are not, then there is water in the gas. If you are running it on the flush kit, are you starting the ski first, then turning the water on, then turning the water off, then shutting the engine off? That is the correct order for running your ski on a hose. It is the exact opposite of the procedure for an outboard. Skis do not have the rubber water pump impeller that requires water to prevent it from melting. Also, because of the design of the engine and exhaust, without the exhaust pressure of the engine running, the water will fill the engine with water by way of the exhaust system. If you are running it in a lake and it is doing that, then more than likely either you have a warped surface like cylinder head or exhaust manifold or a crank in the water jacket somewhere.
Not exactly. You definitely want to start it with the hose off, once it starts, turn the hose on. When you get done tuning, turn the water off before shutting the engine down. If everything is mechanically correct inside the engine, IE nothing like a crack in the water jacket or warped head, it will not get water in the engine while it is running. If you do not run the water with the engine off following this procedure, but still get water on the spark plugs, there is a mechanical problem inside the engine.