Basically, an out-of-control diesel can't be shut down by traditional means when a combustible material - usually oil escaping from another part of the engine - gets sucked into the air intake. Common causes of runaways are turbocharger or supercharger seals that have gone bad, an overfilled crankcase spraying oil out of the breather, or an external source of flammable gas or liquid. If, for example, your genset fuel line ruptured near the diesel's intake, you could be in for a runaway. Stopping a runaway is fairly simple-just cut off the engine's air supply. Of course, when black smoke is billowing all around you, the diesel is roaring at full volume, and you're trying to back into a slip, this is easier said than done. But these runaway - taming tricks should help you get everything back in order.