Need some helpful advice fellow boaters, my symptoms are soon as it hits between 3-3500 rpm it sets off the guardian alarm, a long beep and have to come back to idle for it to re-set. I have completely checked the cooling system, no blockages in the heat exchanger, replaced new raw water pump, engine thermostat, checked exhaust elbows, bravo 1 leg, in the water again out on a test run with a diagnostic handheld unit and its coming up with overspeed code ? Any suggestions on what the problem could be? Thanks in advance.
It is not sensing that it is in gear. The 496 will not allow you to rev it above, from memory, 3200. If you try to it will set an overspeed code. Have a Merc Tech with a CDS hookup to it and see if it senses the shifting.