Electrical Mystery

[Fischer53]

Boat - 170CC with Yamaha 70 HP 2S, both 2004. Guages are Yamaha digital.
Problem - Intermittant dead ignition, guages, and power tilt
Mystery - Nav Lights and Bilge Pump still work, and most importantly, the ignition will work IF I use the power tilt on motor! Unfortunately I did not find that fix until after SeaTow brought me in for $250. I also have a strange symptom where my altenator will drop down to 10v - 11v while at idle then the guages will go blank although the motor keeps idling. Also my voltage will fluctuate quickly between 13.4 and ~11.5 while running. Bringing the idle speed up to around 10k rpm gets things back. Is this a digital guage characteristic?

Everything seems to work fine for the first 1/2 hour. The intermitant has only shown up after several hours, but I was always reluctant to shut off the motor if drifting before this happened.

I would like to have some clue as to what is going on so I can get the right person to work on it.

[Dick@merrittmarine]

Fischer, It sounds like a ground problem to me, something in the engine harness or on the motor itself. It's time to take it back to the dealer.

Dick

[Cincinnati]

I agree with Dick. Cean up your terminals at the battery, look under the console and check all connections there, look under the cowl of the motor and check there as well for corrosion. Two years ago, I had a ground connector unplug under my console in heavy seas - all sorts of strange stuff happened. My horn was muffled, dash lights went out, nav lights out, but the motor still ran.