9Yr old B&S 20 HP Fuel Problem?

Question

I just rebuilt the carb and fuel pump because of poor running and fuel built up in crankcase. It runs great for about 10 seconds then runs very ruff and then fuel starts coming out of the vent holes on top of carb til I close shut off. The only thing not changed was the plastic float and the needle valve seat. I did check float for holes and found none. Is this the float sticking or something with the fuel pump? Is it possible for the float to warp?

Answer 1

The height of the float is probably not right. There is a tab you can bend to adjust it. The float is supposed to close the needle valve when the gas level is high enough but before it gets so high it overflows. Looking may not reveal pin holes in a plastic float. Take it out, shake it and see if it has fuel in it. Or, better yet submerge it in a pan of water and look for bubbles. If the float is good look closely at that seat. It may have a nick in it which is bypassing fuel.

Answer 2

Sounds like the float valve is not closing.  If the float is sound it should be fine.  I believe that the needle valve and seat need to be replaced.