Ignition help needed

[Redeye]

Having a problem with my boat engine shutting off when I come in to the dock. When I turn the key off the motor will not shut off (sometimes). I have recently replaced the key switch and thought that was the problem but it was not. I can kill the motor by pulling the coil wire and then fire it back up and the key switch will shut the motor off. It is a 1986 Mercruise 170 hp I/O. Any help on where to start looking would be greatly appreciated. Thanks

[Tad Pole]

ok couple questions,

1. does the hot wire from your key switch go to the power side of your coil,or does it go to a relay box that the goes to the hot side of the coil.

2. does the engine continue to run or does it "diesel"

3. ok last one are you sure that the switch you replaced was replaced with a good switch?

I''ll look back tonight