I purchased a fishing boat with a 90 hp merc a 1987 I believe. It had been sitting in the elements for 3 years. I completed the normal procedures for preping an engine that has not been started for a while. The problem I have is that when I hit the key the engine cranked fine and began to start and sputter a bit but died quickly however, the starter motor stayed engaged, not with the gear spun all the way out to the flywheel but it was still spinning. I turn the key off and it still remained on. I had to disconnect the battery to stop it. I then thought I would reconnect the batter in a few minutes and when I did sparks flew everywhere. Once I got my heart restarted and said a small prayer I decided to ask the pro's. What's happening?