You must be close to finding it.....or not. I mean it is a boat.
Still thinking about the 10-15 second delay before shutdown and what could cause it. Mako knows these distributors and could comment but I am wondering about the possibility of an installation/wiring issue where somehow there is a "floating" ground that causes the engine to get a signal from the distributor for a while, but then a charge difference builds up and the MEFI is no longer told to send a spark. I mention this because the new distributor could be fine, but when you take it out and move it you could solve the problem by accident but not really need a new part.
Weird idea and maybe not really possible. But boat electricals are always a little weird. You might go back and examine your installation with an eye on weak or missing grounds.
Still thinking about the 10-15 second delay before shutdown and what could cause it. Mako knows these distributors and could comment but I am wondering about the possibility of an installation/wiring issue where somehow there is a "floating" ground that causes the engine to get a signal from the distributor for a while, but then a charge difference builds up and the MEFI is no longer told to send a spark. I mention this because the new distributor could be fine, but when you take it out and move it you could solve the problem by accident but not really need a new part.
Weird idea and maybe not really possible. But boat electricals are always a little weird. You might go back and examine your installation with an eye on weak or missing grounds.