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RSRBOB
RSRBOB, Technician
Category: Boat
Satisfied Customers: 1078
Experience:  Former Yamaha Factory Service Rep, Dlr Line Tech, Serv Mgr, G/M
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1992 Kawasaki 650 jetski. Will run great 10min and then only

Customer Question

1992 Kawasaki 650 jetski. Will run great for about 10min and then only will idle.
Submitted: 1 year ago.
Category: Boat
Expert:  RSRBOB replied 1 year ago.

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?

Thanks

RSRBOB

Customer: replied 1 year ago.
I have replaced the one way air regulator valve on tank because it was faulty and cleaned out filters and replaced primer ball. It does different things after the ten minutes. Sometimes it will stall right out and other times it will rev back up a couple times and then stall out. It does seem to ideal fine.
Expert:  RSRBOB replied 1 year ago.
Thank you for the additional information.
I would like you to try something. The next time you run the ski and after the 10 minutes, open the cap to the gas tank and see if it sounds like it is letting air in, such as the tank was under a vacuum.
Thanks
RSRBOB
Customer: replied 1 year ago.
I actually did that as well. There was no sound of air escaping.
Expert:  RSRBOB replied 1 year ago.

Did it affect the way the ski ran, as in, did it help?

Customer: replied 1 year ago.
It did not effect the way the ski ran at all.
Expert:  RSRBOB replied 1 year ago.

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.

Thanks

RSRBOB

Customer: replied 1 year ago.
Compression on bothe cylinders is 130psi cold engine. Same exact as my other jetski that runs great.
Customer: replied 1 year ago.
I don't think it is losing spark because it starts right up all the time and will actually start up as it is dying.
Expert:  RSRBOB replied 1 year ago.

Thank you.

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?

RSRBOB

Customer: replied 1 year ago.
The valve allowed air to go both ways. It felt like while I was driving it that the bulb would get soft. I took the bulb off of my good jetski and put it on the bad one and the bulb stayed hard but still would die out but not as often. Do you think it could just need a carb rebuild?
Expert:  RSRBOB replied 1 year ago.

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?

Thanks

RSRBOB

Customer: replied 1 year ago.
It did not make a difference. I thought it might because in the Manuel it said check that first every year. Thought maybe it helped regulate pressure in tank. If not regulated thought it might mess with the flow of fuel to carb. I took carb apart and baffles look trashed. I ordered a rebuild kit. Do you know what the adjustments on the carb do. I am not going to touch anything until I rebuild it and run it. But if it needs some sort of adjustment I would like to know what each set screw controls.
Expert:  RSRBOB replied 1 year ago.

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!

Thanks

RSRBOB

Customer: replied 1 year ago.
I rebuilt carb. It definitely needed it. I put everything back together even double checked to make sure things were right. I put everything together and it won't start at all now. What can i do to test whether or not fuel is getting to spark plugs?
Expert:  RSRBOB replied 1 year ago.

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.

RSRBOB

Customer: replied 1 year ago.
Started 5-6 times but won't keep running. Now won't start. Plugs have whit type foam around them. Not sure what it is. Water and fuel mixture?
Expert:  RSRBOB replied 1 year ago.

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.

RSRBOB

Customer: replied 1 year ago.
I was running it on the hose. I just had the water on the whole time. So I can leave water off and get it running and tuned in before having to turn hose on to prevent overheating?
Expert:  RSRBOB replied 1 year ago.

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.

RSRBOB

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