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RSRBOB, Technician
Category: Boat
Satisfied Customers: 1078
Experience:  Former Yamaha Factory Service Rep, Dlr Line Tech, Serv Mgr, G/M
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I have a 1995 Yamaha Waveraider 700 that starts fine and runs

Customer Question

I have a 1995 Yamaha Waveraider 700 that starts fine and runs fine for about 10 to 15 minutes. After that is looses power and will only go about 10-15 miles per hour and sometimes just quits. It is not overheating but I have disconnected the thermal switch to see if that was the problem and it is not. This consistently happens. I had a local mechanic do a quick diagnosis and he indicated it could be the stator. I am just trying to confirm what the cause of this issue is.
Submitted: 2 years ago.
Category: Boat
Expert:  RSRBOB replied 2 years ago.
Hi and thank you for your question.
My first question for you is has anyone done a compression test on the engine? It certainly sounds like it could be an electrical problem, but it could also be a mechanical issue.
If you have done a compression test, what were the results? If not, you need to do one first before attempting to diagnose the electrical system. We need to know which direction to go with our diagnosis to get you back up and running as quickly as possible without wasting your time looking for a ghost.
Customer: replied 2 years ago.
Hi RSRBOB, I had the compression checked two years ago when this problem first surfaced and it checked out fine. There has no no water in the north end of lake Travis where I live until a few weeks ago. Anyway I wanted to launch it and run it around so I could better describe the problem. The ski started right up and ran great for 20 minutes reaching a top speed of 52 to 55 consistently. I then slowed down from running it at 40 to 50 to about 15 to 20. Well at that point it would not reexcelate. It wanted to but just could not. It dropped down to where it would only go 7 miles per hour and was just bogged down. Stayed very close to home so pulled it out brought it up to the house. Turned off the gas and started it to clear the water from it and it ran at full rpm. What are your thoughts. Oh and sorry for taking a while to respond I travel during the week
Expert:  RSRBOB replied 2 years ago.
Thank you for the additional information.
"IF"the ski will still run in the 52-55 MPH range for the first 15 minutes, we will look elsewhere for a problem. If it is not hitting 50+ MPH, I would really like to have the compression tested again.
This sounds like a fuel supply problem (assuming it is not a mechanical issue). Essentially what it sounds like is happening is the fuel system cannot flow enough fuel to sustain WOT. (wide open throttle).
With that thought in mind, the best thing to do is start going through the fuel system, starting at the fuel tank pick ups. I would pull them out of the tank and inspect them and blow air through them. They should flow air quite freely. Start there and work your way back, checking the fuel lines between the filters and the pet cock. Again checking for unrestricted air flow. Inspect the fuel filter, paying close attention to the presence of water or debris. Check through the pet cock in both the on and reserve positions. Continue on down to the carbs. If the fuel supply line is free flowing, we are going to have to pull the carbs and inspect them internally to see what is going on there. Let me know if you get to the point of having to pull the carbs and I will give you some pointers there.
Best of luck,
Customer: replied 2 years ago.
Hello, OK, I completely cleaned out the fuel system to the carb intake and removed and replaced the gas in the gas tank. It starts right up great, however when I put it on the water this time it would not accelerate past 15mph.

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