I have been experiencing severe electrolysis on 1 of my outboards. After chasing down possible bad grounds and beating my head against a wall I found an article on the interweb about the rectifier going bad. I did notice that the tach was intermittent. I did replace the zincs but that didn't help. It actually ate the trim tab almost off at the end! Now I will go spend some hard earned money on a rectifier....we all know what boat stands for
