At the Lake, need help. 2003 mercuriser 5.0 mpi keeps shutting off randomly.

[Wipley1]

Ok, newbie here... I have a 2003 Galaxy Runabout. It has a 5.0 mercruiser 5.0 mpi with an alpha 1 drive. It only has 112 hours. Its never had problems its been a great boat. Heres the problem, the last couple trips out it been shutting off at random times, like someone turned off the ignition. I'm thinking bad ground. I have checked battery and starter connections, all tight. It will die then start right back up. Sometimes for 1 min and other times 20 min. The only thing I notice is the oil pressure, drive elevation and the tach are having issues. Oil pressure goes from 0 to 42 pounds at a blink of an eye. If i put the drive up or down the oil pressure will sometimes go from 0 to 42 pounds.The tach just seems to fast, it sometimes read 5000 rpm at what should be closer to 3000 rpms. Just before the boat shuts off I do get 2 audiible beeps. Yesterday it stopped twice on the way in. I shut the key off and the fuel pump stayed on, had to shut off the battery switch to shut it off. "That was a first" I've done some reading, fuel pump relay? Could that have been the issue and now has failed. Nothing like going somewherenot knowing you'll make it back. If anyone can make since of my post and has any suggestions please feel free to let me know. Thanks in advance...

 

[o2batsea]

First of all, please don't use the boat until you resolve this huge safety issue. It sure sounds like an electrical problem, maybe something as simple as a bad key switch. Are you comfortable doing electric troubleshooting?
Now this is probably not true of your boat but I will say that I have seen some extremely awful factory wiring that is nowhere near compliant with ABYC guidelines nor even safe. Boatbuilding is an unregulated industry and quality varies.