3 hp yamaha trobble shooting

[jballard]

i have a 1994 3 hp water cooled yamaha that bogs down and stops running under load but runs at all rpm in netural. the carb has been cleaned 4 times by 3 different mechanics, the charge coil, exciter and other coil has been replaced, fuel pump has been cleaned and check, gas tank has been cleaned, spark plug hs been replaced. factory could not help the "master yamaha" mechanic. the mechanic sprayed gas directly into the carb and that did not help. engine acts like something has hold of the prop when in gear but engine cranks easily in gear. compression is 125 psig.

any suggestions???

frustrated!

[99yam40]

good compression, good spark, proper advanced timing, and the proper fuel/air ratio are all things that need to be there for proper running under load.

Are you sure voltage to and out of coils and timing are all in spec

[robert graham]

I have a 3HP Tanaka Outboard and whenever it has bogged down or shut off under load it's been a restriction in the fuel flow or a restriction in the fuel tank vent. Check your on/off pet**** for full flow operation...maybe even bypass it temporarily just to see. Some pet****s have small screen mesh filters in them that can get plugged up. Is your fuel tank vent working properly?...maybe try running the motor with the cap slightly loosened or off just to double check? Good Luck!

[BQUICK]

I've found that these 3hp motors have carb issues due to having no fuel filter. Why they put one on a 6 hp Yamaha but not on a 3 is beyond me. The 3 has tiny passages that clog easily. I finally put a filter on mine (after cleaning carb for the 4th time!) and have no issues since.