dajohnson53
Lieutenant Commander
- Joined
- Apr 28, 2004
- Messages
- 1,627
Spent the weekend at a friend's cabin which is accessable only by boat. We met him there about a day after his family had arrived. When we got there he complained that his outboard just wasn't working like it should - started OK, but just didn't didn't have the oomph out of the hole. He's talking dirty carbs and what sort of additive he could put in his fuel to clean the carbs.<br /><br /> Later we were out on the lake getting ready to pull the kids tubing and he was showing me what he meant, but since I'd never ridden in his boat before, I really couldn't tell what the performance decrease was except...<br /><br />He told me he hadn't changed his plugs this spring (but only put about 30 hrs on the engine last year) and ...<br /><br />I tried pumping the bulb while accelerating, no effect. I then noticed it was topping out at about 4000 WOT. I asked and he told me it usually ran somewhere above 5000 at WOT. Hmm I thought, this could be the famous "approximate 25% decrease in WOT in a 4 cylinder caused by a cylinder not firing" that I read about in IBoats Boating Forums! And since he hadn't changed the plugs, it could be a bad plug!!<br /><br />I suggested we take out the plugs and look at them and sure enough one was obviously fouled and not firing. The others looked perfect.<br /><br />Changed the plugs and all a sudden the thing almost stands on end out of the hole and quickly gets up to somewhere between 5000 and 5500 WOT.<br /><br />Last year I couldn't have made this educated guess. Probably I would have suggested changing the plugs anyway - it would have been all I knew to do other than take it to a shop. This year, I could guess based on the performance and the look of the plug, and if changing the plug hadn't worked, could have traced it back at least to the power pack, fuel pump or carb possibly.<br /><br />Baby steps, but kind of fun and my friend thinks I know something.
