[Hudson River Steve]

As Dan suggests, you should get a manual for locations etc. You may want to ask a Merc Mechanic to come for a ride along with his scan tool plugged in, it will probably be worth the hour of his time. Hopefully the problem will occur while he is on board and he can locate the bad sensor or wire. It could be any of the things I already described or it could be other things like the MAP sensor wiring. It will take a process of elimination...nothing worse than an intermittent electrical problem. Happy Hunting.

[DFZ272]

Scott, I just thought of something while working on my boat this weekend. There is an oil pressure safety shutoff switch which is seperate from the gauge sending unit. If u have a remote oil filter follow the lines down where they connect to the engine block. If you dont have a remote filter, the sensor should be next to the oil filter. The sensor should have one wire, probably tan and blue. On MPI this switch will also shut off the electric fuel pump. Just something else you can check.
Happy Boating
Dan