Fuel Draining in to Crankcase

[Lord Mort]

So you're saying that this problem still happens while the engine is running? You've got a bad fuel pump then.

The fuel pump has a thin diaphragm in it - it uses crankcase pressure pulses to move the diaphragm, on the opposite side of which is the liquid fuel (and check valves) that is pumped. When the diaphragm leaks, fuel will go directly into the crankcase. If you had that much fuel running into the engine via the carb, it wouldn't even run due to a too-rich air-fuel mixture.

Sorry that I didn't understand your situation originally.

No worries... so if it uses "pressure pulses" then there is no armature or shaft (and therefore, linkage) that I need to worry about?

I could just simply unbolt the darn thing and verify that is where the fuel is leaking?

 

[Lord Mort]

Sure enough... leaking right out the back of the fuel pump.

Got a new one on order already. Thanks guys!

 

[Farmer Dell]

I have the same problem, had the machine for decades - Dag Float!

 

[keakar]

Hello,

I was looking for some suggestions on how to resolve this problem.

The fuel on my riding lawn mower is draining in to the crankcase. The engine runs perfectly (when the oil isn't diluted) so I'm inclined to think the block and intake gaskets are fine.

I just replaced the carb as I was told it was most likely vapor locked... That was not the issue.

Any ideas?

The mower is a crafstman 917.271012 and has a 15HP Kohler Engine.

Thanks!

assuming the new carb isnt defective, there must have been some trash dislodged in the fuel line when you reconnected it. pull the crab and float and clear the blockage keeping the float needle from shutting off. if its clear then you have a bad float needle and/or seat so send the carb back for replacement.

when you think its done, put the carb in position on the bolts but not fully installed, connect fuel lines and shut of solenoid, then turn key on and wait a minute or two to be sure its not still flooding and nothing is dripping out of the carb. this stops more gas from going into the cylinders and saves a bit of time if you have to take it back off

EDIT - ok, just saw you solved it. good catch.

still, the info i provided above is a very good practice to use anytime you reinstall a carb just to double check things