I recently aquired a ski/fishing boat with an '82 Mariner 90 HP inline 6 hanging off the back of her. When I initially looked at it, it seemed like it had a miss when cold, but ran fairly smooth when warmed. A compression test showed 130-135 psi straight across the board. Out on the water, it stalled a fair amount at idle, seemed a little slow in the holeshot, and the rpms were low...I attributed this to the wrong prop....I had put a 17 pitch on while the 15 was getting repaired. Anyways, while doing a tuneup in the backyard today, the #6 plug was clean as a whistle....I ohmed the plug wire out.....it was pretty much open....and the coil was severly burnt/corroded at the contact were the plug wire plugs into...anyways, I dont think that there was any way that this cylinder could have been firing.....but it ran really smooth on the water. This is my first outboard, but are two strokes that deceiving, or am I just out of it??
