why does fuel fill up the crancase in my chinese 150atv? after running the 150atv for a half day of so the engine crancase will fill up with fuel and when it is running fuel will spew out of the breather tube located on the on the cylinder head cover. i have replaced the carb twice and it still floods.
why does this happen? i have a chinese atv with a 150cc engine that is a honda scooter clone engine with a electric auto choke cv type carburettor

joe dirt, January 2007

My guess would be that the carby is flooding whilst the engine is not in use. The carby float valve is letting fuel through. It is possibly stuck or blocked open with some dirt; the float could have a leak in it and has filled with some fuel making it sink.

Pull off the carby bowl (bottom of the carby) carefully and gently blow into the fuel inlet whilst manipulating the float to see if the valve is working correctly.

The float is usually set in such a way the the valve is closed when the top of the float is parralel to the carby body/bowl interface.

Good luck.

Aussie Ron

Ron, January 2007