I have a 1990 johnson 48 spl have never had any problems with it. Recently I went out to charge battery and before I hooked up charger I could smell something electrical had burnt.discovered my wiring harness between plug on motor and ignition had.melted and caught on fire. Assumed the harness was old and had worn a hole threw insulation and shorted out on aluminum boat somewhere. Everything was severely melted so it was hard to tell. Got new harness and it started getting hot as well. It is definitely the ground wire in harness getting hot. Don't even know where to start. Cables from battery to motor are good and clean, cleaned grounds on motor any ideas?