Gas is leaking into the crankcase

[sblg43]

My cousin just contacted me and has a bit of a problem. She has a Simplicity 12RTH tractor with a briggs and stratton 12 hp model 283707.
She and her husband replaced the carb and fuel line after finding that the fuel is draining out of the tank and getting into the crankcase. But now, with a new carb, it is still happening!


In the past, I dealt with this problem (on a different tractor) by putting on an inline shutoff. Shut off the fuel when you are finished and the tractor runs fine.

But why would this happen in the first place?

[bobodu]

Usually dirt under the float valve. I don't have time to pull the parts list but a hole in the pump diaphragm will flood a case too.

[KE4AVB]

2nd the trash idea. Pull the fuel bowl and check it. If trash is in there then it be at the valve seat too.

When I pull up the basic engine IPL (61 different type numbers shows up), it showed a possible engine mounted tank that can have trash in it.

[bgsengine]

Yeah - also replace all fuel lines after the filter to the carb - fuel lines rot out from the inside and bits of fuel line will do exactly that - and as bobo said, if fuel pump equipped, ruptured diaphragm can dump gas into crankcase through pulse hose.