I have a 2001 40hp 4-stroke Mercury that I purchased late last fall with a pontoon boat. It was only run twice...first when I purchased it and the 2nd time when I put it in the water, putted around the lake and pulled it out for the winter. I'm quite sure I had it on mid- to high throttle when I purchased it.
Since the start of this summer it feels like it's missing when I start to throttle up. It doesn't sound different, but it definitely hesitates constantly until I back down on the throttle. It starts fine, idles fine and I can putt around the lake at low speeds (I'm guessing up to about 25% full speed) without any issues.
I originally put in Sea Foam. No change. I changed the plugs (3-cylinder), with no change. The plugs I pulled out didn't look abnormally fouled (black, but not fouled).
A friend of mine said he had the identical problem with his pontoon and it was water in the gas. That was "cleaned out", the mechanic said just put HEET in future gas tanks and he'll never have the problem again. I did that and no difference yet, although I admit I have very little time on the engine since doing that (it was in the tank for 1 2week before I ran it).
I put in new non-oxygenated gas in the tank at the start of the summer (filled 6-gallon tank, about 1/2 full right now).
I'm a little concerned that there's a larger problem. My plan is to continue using it at low speeds, because I only have a few weeks left in the season. Then, take it in next early spring. But, I'd sure like to see if it's something I can fix before bringing it in, i.e. it needs 1 hour of runtime with HEET before it gets rid of any "bad" gas in the motor. My buddy says it may take multiple tanks, but at the rate this thing burns gas that may take years.
Any help would be greatly appreciated. I am basically non-mechanical when it comes to engines, so please be nice with your response
Since the start of this summer it feels like it's missing when I start to throttle up. It doesn't sound different, but it definitely hesitates constantly until I back down on the throttle. It starts fine, idles fine and I can putt around the lake at low speeds (I'm guessing up to about 25% full speed) without any issues.
I originally put in Sea Foam. No change. I changed the plugs (3-cylinder), with no change. The plugs I pulled out didn't look abnormally fouled (black, but not fouled).
A friend of mine said he had the identical problem with his pontoon and it was water in the gas. That was "cleaned out", the mechanic said just put HEET in future gas tanks and he'll never have the problem again. I did that and no difference yet, although I admit I have very little time on the engine since doing that (it was in the tank for 1 2week before I ran it).
I put in new non-oxygenated gas in the tank at the start of the summer (filled 6-gallon tank, about 1/2 full right now).
I'm a little concerned that there's a larger problem. My plan is to continue using it at low speeds, because I only have a few weeks left in the season. Then, take it in next early spring. But, I'd sure like to see if it's something I can fix before bringing it in, i.e. it needs 1 hour of runtime with HEET before it gets rid of any "bad" gas in the motor. My buddy says it may take multiple tanks, but at the rate this thing burns gas that may take years.
Any help would be greatly appreciated. I am basically non-mechanical when it comes to engines, so please be nice with your response