The breather tube connects with the crankcase, so if there's fuel coming out of it, the CRANKCASE IS FULL OF FUEL - STOP trying to start it until it's sorted - there is a substantial risk of explosion or serious fire. (Please take this seriously - not a joke - it happened to me and I was lucky to walk away).
This is usually caused by a ruptured diaphragm in the fuel pump, allowing fuel to be drawn directly from the tank into the crankcase via the vacuum tube that powers the pump.
If there is no fuel pump fitted, the the cause will be a leaky carb inlet needle, allowing fuel to fill the engine via the inlet manifold while at rest.
Fortunately, the fuel pump, or a carb kit, is only a few $$$, but drain and refill with oil before starting.
Good luck!
phil(saunders(a)bigfoot.com
Phil Saunders, May 2012
