Yamaha 50 hp won't go full throttle

[frenchy22205]

I have a 50 hp that will start up ok and idle ok and the manual throttle will rev up pretty high. When I put it in gear and try to speed up it will only go about half speed. I know if the oil is low it will reduce the speed but it's full and the green LED is on. The water pump was replaced last year. I tried to clean the carbs with carb cleaner but that did not help. I bought a new tank and filled it with new gas and that didn't help. One of the carbs had a sticking float but that fixed itself (probably from vibration). It's a 1987 vintage yamaha and has worked fine every year until now. What should I do next? Have the carbs rebuilt?

[Ken]

frenchy,
If the outboard was allowed to set up for at least six months without being run, then the carbs are probably gummed up - I would get them overhauled. But before you do, make sure the fuel filter is clean - maybe the motor is starving for fuel at high rpm.
Good luck,
Ken K

[stevemon]

I agree with the carbs as the culprit. As long as you have them off, to be sure do the complete re-build (needles and all). Mine get gummed every year (one day I'll learn!) and seems the "stor" products make it worse.

[jb123]

probably fuel delivery ..have you also checked your fuel pumps for bad diaphrams? you may have to go thru carbs 2-3 times to get them right. check everything from fuel pickups,connections,if you have a quick disconnect,rid of it and run the hose direct. a simple air leak can cause that also.my first check on any power weakness is a comp check tho.