2002 Yamaha 40hp Problems

About 6 weeks ago I was getting the boat and motor cleaned up for spring/summer. The motor wouldnt hardly start and when it did, it didnt run smooth. I took it to the shop and repairman said it was water in the fuel tank and dirty carbs. He serviced carbs for $80 each (x3). Motor ran fine for 3 weekends in a row. This past weekend approx. 4 minutes from dock, running at full speed, motor lost power and struggled to push the boat. Maybe running a 1/4 speed. It starts fine and when hooked to the water at home it idles well and seems normal when put into gear at low speeds.

Any ideas????

[boats.net]

Check the fuel filter on motor to see if more water is in it.

My 2001 40HP seems to be doing the same thing. When you move the throttle up it sounds like the prop is spinning like it should and it creates one huge wake behind the boat but the boat is hardly moving. I had the carbs cleaned a couple of months ago but took it out last week and same thing is happening. The primer bulb is hard when I try to pump it. Even at idle speed it runs kind of rough. Does this sound like the same issue?

Ventilation

At the risk of sounding like a dummy, how would I measure that? Measure from the top of the transom to the prop? Sorry for what must be a pretty silly question.

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will this work?

no I do not have a tach on it, it has run fine for 2 years and then this year in March the first trip out in the river it did this. I thought it was possible that it may be from where the gas was left in over the winter and the carbs were gummed so I took to the shop and he says he cleaned them. It worked great for the next 2 trips and then it was back doing it again. It revs up and the prop spins like it should when you push the throttle up but the boat barely moves forward. I thought it was a 2001 but it may be a 2002. 6H4 L 934063 R is serial number if that helps.

Idolan, did you get your problem resolved? Still not sure what is causing mine.

Thanks for the response. I will check the fuel tank for water. Can you recommend anything for me to do to prevent carb trouble if it is that again? Kind of puzzles me that the carbs are messed up again after 2 months of being cleaned supposedly. I use the boat about once or twice a month. Is there any kind of tutorial on the internet that shows how check the carbs?

Thanks again for your time and answers.

[boats.net]

Scratch a line across the hub of prop and prop washer(the prop washer is splined and will not turn, the prop is on a rubber hub). Take boat out and run it, then look at the line you made. If the line is misaligned then the prop is slipping.