02 Yamaha 30hp 3 cylinder problems/fixes!!!

[3cylyamihammer031]

Ok guys I have searched until I was blue in the face. It seems it’s a crap shoot on trying to find outboard build threads or anything performance related to these engines. My engine is a 2002 Yamaha 3 cylinder 2 stroke with intact oiler system. The problem I am having, I completely rebuilt the fuel pump on this engine. When I opened it up one of the check valves was stuck open. Seemed to be distorted or bent. I replaced everything and went on about my business. Fast forward 3 trips to the river with the motor running flawless, we were frogging last weekend and about half way through the night I got the same fuel pump symptoms. Wouldn’t idle, would bog down under acceleration, and had a heavy smell of fuel. I tied off and removed the fuel pump to find the same check valve was bent again. This time I bent it back into shape and continued on through the night. This is the third time I’ve had this problem in the 4 weeks I’ve owned this motor, as it was showing these same symptoms when I got it, and I just bent it back and ordered the rebuild kit. What would cause this to continuously happen, is there a definite fix?

[Capt.Insane-o]

Does it sneeze on cold starts..or at all for that matter?

[3cylyamihammer031]

No, it runs flawless.

[FMP]

Using Yamaha parts?

[3cylyamihammer031]

Yes, 100% Yamaha parts.

[Capt.Insane-o]

Take a pic next time it happens.

[3cylyamihammer031]

All times it has happened the check valve has about a 32nd of an inch gap between it and the seat.

[FMP]

Which of the two?

[3cylyamihammer031]

The one that’s on the carb side.

[FMP]

Tank venting properly, hose clear to sump, check ball, all that good stuff etc?

[3cylyamihammer031]

Everything is new and working properly.

[3cylyamihammer031]

It happened to me again the other night. It only happens after long periods of being wide open. I fixed it again and the next day I pulled it apart and swapped the check valves around. Ran the crap out of it last night and it did great so I’m leaning towards that one check valve being weak from the factory.

[FMP]

Check for an imperfection at the valve seat surface on the body? Slightly angled etc.
Both the same part, should repeat fail

[3cylyamihammer031]

I will if I have to take it apart again.

[FMP]

Is it propped or ported etc to turn more rpm?

[3cylyamihammer031]

Motor is 100% stock and I’m running a 14 pitch 4 blade prop. Rpms sound good as it’s not screaming but I haven’t put a tach on it yet.