Yamaha FT 50 CET outboard problem

[GART]

I have a petrol leak when the engine is tilted in the fully up position. Petrol is dripping from the air filter. I have taken the carb stack off, and when tilted to the same angle as when leg is raised the bottom carburettor out of 4 is filling up with petrol, held back by the throttle butterfly running slowly into the air filter. I have checked the float & valve, both seem to be working fine. There does not seem to be any adjustment on the float or needle valve, the needle clips onto the float pivot. Any Ideas how to stop the leak? Or what could be causing it?
Any advice would be appreciated. The engine is a four stroke 50 hp 2001 model with only 425 hours use.

 

[RichardS]

Unless something is cracked somewhere I think it has to be a leaking float needle valve. It could be the needle is slightly damaged or the valve seat. If you've blown it all through and it's definitely not just dirt then the only way to be 100% certain of a fix is to change the needle and the valve. I usually test them by sucking through the fuel inlet to the carb once it is rebuilt. If you suck hard (you might need to tip the carb to close the valve initally) and cannot sustain a permanent vacuum with your tongue over the end of the inlet then it is no good.

Richard

 

[VicS]

I have a petrol leak when the engine is tilted in the fully up position. Petrol is dripping from the air filter. I have taken the carb stack off, and when tilted to the same angle as when leg is raised the bottom carburettor out of 4 is filling up with petrol, held back by the throttle butterfly running slowly into the air filter. I have checked the float & valve, both seem to be working fine. There does not seem to be any adjustment on the float or needle valve, the needle clips onto the float pivot. Any Ideas how to stop the leak? Or what could be causing it?
Any advice would be appreciated. The engine is a four stroke 50 hp 2001 model with only 425 hours use.

I would critically re-examine the float, the needle valve and its seat.

Adjustment, if adjustment is needed, is usually by bending the float arm or the tab which contacts the needle but I would not attempt to do this without checking the float level and referring to a workshop manual. Yours looks as though it might be entirely plastic anyway.

See the warning note in your owner's manual regarding disconnecting the fuel line, or closing the fuel cock, if the engine is to be tilted for more than a few minutes. It sort of implies that what you are seeing is normal.

 

[GART]

Thanks Richard & Vic, I have now tested the valve again using Richards method of sucking and it held a vacuum. I have also taken apart again, the float is entirely plastic with no adjustment, however it is exactly correct according to the manual the needle valve is rubber tipped and in new condition no chips or marks where it seals even. I blew compressed air both ways through the hole from what I can see it is fine.
There is no fuel cock, but I did disconnect the fuel line, however fuel is still coming out from the air filter when fully in the up position, ok when vertical or trolling.
maybe I am being over cautious, but after my explosion & fire in 2014 I do not even like the smell of petrol under the hood.