Small Engines (Lawn Mowers, etc.): B&S v-twin

Question
I have a 23 hp Vanguard v-twin. For some reason when you turn off the key it will continue to run for about 15-30 seconds. Not very safe on a grain auger! Can you tell me why this is happening and how to fix it?

Answer
Check your ground connection and key switch connector/connection.

There is small gauge, single wire, that connects to the engine block.  It is usually a push-on spade terminal.  There will a couple of alternator wires and possible a wire or two connected to the carb...this is not the wire you are looking for.

Does the engine have an electric start and a battery?

Eric