I have bought this zero turn zg227 , mowed great then went to check the oil the next morning and crankcase is full of gas! Carburetor is clean, with the key on and the engine off the fuel pump runs constantly, I don’t know if it’s supposed to reach a certain pressure and cut off? The engine does stay running after you turn the key off for a few seconds. If anyone can point me in the right direction this would be helpful thanks.