Engine will not shut off?

[steve51]

I have twin 1991 200TXRP engines and the Starboard engine starts and runs fine, but will not shut off when the key is turned off. Hitting the choke will kill it.
Could it be anything other than a stuck contact in the ignition switch?

[boats.net]

It could be a bad key switch, bad main harness or bad CDI unit. Since you have twins swap the main harness to other key switch and see it shuts off. Most of the time it's a bad main harness.