Merc90HPnewbie
Petty Officer 2nd Class
- Joined
- Jul 27, 2003
- Messages
- 178
Mercury 90 HP inline 6 outboard, 1985.<br /><br />I was on the water this weekend when I noticed the fishfinder kept going off. I don't fish- in fact most of the time I am going over 25 MPH, but since it was in the boat when I bought it, I leave it on since it tells me MPH, water temperature, and depth. Anyway I kept turning it back on and it would be off within a minute or so. I put it in diagnostic mode and every test passed but it put up two warnings: Overvoltage Detected and Undervoltage Detected. The voltage readings it gave varied between 16.4 and 17.6 volts. This was at 3100 RPM but I checked again when I was going slower and it was the same thing. (For comparison, I think a running 12V system in a car is supposed to be around 13.8V at idle. I don't know if an outboard should be the same.) 17.6V sounds high to me but that only explains the Overvoltage Warning not the Undervoltage one.<br />The fishfinder has turned off in the past but never this often. I am guessing I have something wrong in the charging system. I guess the first step is to put a voltmeter on the battery and make sure the voltage really is going too high and too low. Assuming there's no loose wires or other obvious problems, what components should I be focusing on here and does anyone know what part is a likely culprit? <br /><br />Thanks!!