1993 40hp Yamaha Fuel Problem

[windknotnc]

I have a 3 cylinder 40hp Yamaha that cranks and runs perfect for about 100yds then starts cutting out and will not take the gas. It sound like it is missing and only will run about 1/4 throttle. If you cut it off and crank back up it will run another 100 yds perfect but then start cutting out. The fuel line bulb is tight, the gas fresh, and the carbs were cleaned about 3 months ago....The engine was doing this during duck season and my son cleaned the carbs and said it was running great. He ran it yesterday and today and the problem is back. Is it possible there is a stuck float in one of the carbs? Any ideas on where to start?

 

[SAMCHAMP]

Re: 1993 40hp Yamaha Fuel Problem

did you check fuel pump to see if diaphram is leaking

 

[windknotnc]

Re: 1993 40hp Yamaha Fuel Problem

Have not checked that...will look at it. I am guessing this is best done by replacing as small pin holes may not be visible?

 

[windknotnc]

Re: 1993 40hp Yamaha Fuel Problem

Just looked at the diaphram and it looked good. No pin holes, tears, or any obvious issues

 

[cr2k]

Re: 1993 40hp Yamaha Fuel Problem

OK now for the obvious...Is the fuel tank vent open?

 

[SAMCHAMP]

Re: 1993 40hp Yamaha Fuel Problem

Just looked at the diaphram and it looked good. No pin holes, tears, or any obvious issues

Take youp pump off but leave the fuel lines hooked up and pump your ball look at the back of pump to see if fuel is coming out of pump

 

[windknotnc]

Re: 1993 40hp Yamaha Fuel Problem

No leaking out of the pump....any thoughts on a possible stuck float in carb?

 

[SAMCHAMP]

Re: 1993 40hp Yamaha Fuel Problem

probably need to take carbs apart and clean them again

 

[morrisdan]

Re: 1993 40hp Yamaha Fuel Problem

I have the same motor and the same symptoms. What did you guys figure out?