I could be the coil and you could replace it and see what happens, but I am thinking something in the electronic ignition circuit is defective because of the tachometer issue, if the tach drops out while the engine is still turning over. If you are sure no water is in the fuel, then it almost always comes down to either ignition or fuel starvation. Usually ignition problems cause an instant stoppage. Your stoppage seems a stumbling one with rough running before stopping. So because of this rough running, my other guess is debris in the fuel tank are plugging things up ahead of the filters because the problem occurred in rough weather where the junk in the bottom of the fuel tank are getting into the fuel delivery system. What you need to do is some trouble shooting. Put a fuel pressure gauge after the fuel pump and see if the pressure drops when the engine quits. If you have access to an ignition analyzer, you could try that. Upending a sparkplug in the center of the distributor cap and tying the wire from the coil to it would give a visual indication of a viable spark; however, someone is likely to accuse me of trying to kill you by blowing the boat up if there was any gasoline about in the engine compartment.
Last edited by LakeSuperiorGeezer; 11-15-2011 at 12:34 AM.
Reason: Is tach dead while engine still turning over