OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Briggs ser 31 eng. fuel in crankcase

G'day everyone,
I am wondering if anyone has come across this problem. Fuel in crankcase, I will try to give as much info as I can so please bear with me. A customer brought their Husky ride-on in saying it has hard to start, I checked in out and found fuel in crankcase, drained it out. Filled with new oil and filter still was hard to start. So I then removed engine after reading something on an American forum stating these ser 31 engines are notorious for breaking the de-comp assy on the camshaft. Yes I found broken de-comp on camshaft. I fitted a new genuine Briggs camshaft in engine, put it back together fitted to ride-on started ran fine like it should. Gave it back to customer, he used it for about an hour. It has come back to me again same problem crankcase full of fuel again, so I thought the de-comp broke on the new camshaft. Remove motor, took off sump but de-comp on new camshaft is fine not broken no damage. Also the timing is fine as well. I tested the fuel shut-off solenoid on the carby works fine. So my dilemma is if de-comp is ok, fuel solenoid is ok why is the sump filling full of fuel so it won't start. If anyone has any ideas about this, any help will be truly appreciated cheers Mike

The Decompressor has nothing to do with fuel.
There are 2 ways fuel can get into the crankcase, either through the fuel pump, if the diaphragm has gone, in which case it will be going straight into the tappet cover through the pulse hose, or, the much more likely and common cause if the float valve in the carburettor leaking.
I would start in the carby, check the needle, check the float for cracks/ full of fuel. even though the solenoid closes off the main jet, if the float is leaking it will overfill the carb and still make its way into the intake.

I had this issue with my Husqy LT130. Everything else checked out so I fit a fuel tap in the fuel line between the tank and the carby but before the fuel filter. That solved the issue. Now when I want to use the rideon I lift the bonnet, turn on the fuel chock it it and turn the key.

Only way fuel can flow from the tank is down through the carby and as has been said if the float needle doesn't hold then fuel will continue work its way to the lowest point which is the sump

Without the engine model, type, and date code it is only a guess that the OP may have Nikki carburetor. On those carburetor the float gasket set can cause fuel leaks even when float valve is good.