Originally Posted By: Panzerman
Ive had that happen before. Only way to shut them down is smother them. The old Detroit two strokes actually had a pull out shut-off cable in the cab, that controlled a butterfly in the air box to block it off. I ve had it happen several times on two stroke gas engines too. If the crank seal is leaking, they will take off full tilt and you cant shut them down either. You have to smother them.
Oil exploration machinery have this as well, however, it activates automatically. This is needed because natural gas might leak out the oil well, and then cause a runaway engine.