Mower engine dumping fuel into crankcase

[dlundblad]

Anyone ever hear of a lawn mower engine dumping all its fuel into the crankcase?

The girlfriends dad has an old mower with the same good ol Tecumseh engine as our LB. It had sat in a barn for a few years with low oil, fuel in the carb and mouse nests. We topped off the oil and filled it with a little gas and started it up. It ran for about 5 seconds while puffing white smoke then died. We were unable to get it started again so I dug into the carb. The float floated, but the float pin seemed excessively loose. I dug into it more only to find all the gas was mixed in with the oil. I have never heard of this before. Is the engine shot?

*I've heard of fuel dilution, but I think this is a bit excessive.

 

[EdwardC]

Sounds like the float needle isn't operating right, allowing the the fuel to keep flowing. I'd clean up that area and replace the float needle.

edit: I don't know anything about those engines in particular, my thoughts are for a generic carb

 

[Olas]

After you look at the float pin, look at the fuel pump. If its a mechanical pump the diaphragm could be split..

 

[old1]

It is just the float/ needle and seat not sealing. might need to take the carb off, to easily replace the needle and seat. Does it have the viton seat, or the one that screws in? Screw in type is reeealy old. Also check the float for gas in it by shaking it and see if it sloshes. change the oil, and you are ready to go.

 

[dlundblad]

Thanks for the replies guys. Should have specified: Its a push mower.

 

[jeepman3071]

Yup, +1 on it being a needle/seat problem. I've seen it on a few different engines where the needle valve leaks and fills the whole crankcase with gas.

 

[Merkava_4]

Check the float needle and seat and also make sure all the vents are open.

 

[Nukeman7]

Also check for a crack or pinhole in the brass float or a fuel saturated non-metal float. If it doesn't float, the needle valve won't seat and all the gas will gravity drain through the carburetor on a Tecumseh.

 

[Rand]

I usually put a fuel shut off valve on everything then it cant do more than drain the carb down.

there have been a few times where over winter the whole gas tank has drained into the crankcase... sometimes amounts in the gallons.. ugh

definitely a carb problem.. not shutting off the gas/leaking past