I’m running a 1995 115 2+2 Mercury on an 18ft Astro bass boat. My issue is my #1 spark plug has moisture on it when I pull it and the other 3 plugs look like normal carbon wear. I’m only getting about 38 mph top, but the prop is pitched for a fish and ski boat (19 pitch)
What I’ve done:
New impeller
New lower end gaskets including the prop shaft seal under the impeller since I had some water in the gear oil
Re-tuned the engine per the Seloc. Initially it was idling above 1000 RPM and the book calls for 750-800 RPM. Also adjusted the top 2 carb idle mixtures per the manual. It still runs like a snotty 2+2 at idle and isn’t smooth until a little throttle is pushed in (makes me think #1 isn’t hitting all the time?)
New plugs, checked the ohms on the wires
Re-wired the main power wire since it showed signs of getting hot (stator wire?)
Rebuilt the fuel pump
New fuel and oil lines
Cold compression is 110-112 on all 4 cylinders
Re-torqued the bolts on the cylinder head and the exhaust cover to 18 ft-lb (most of them were 1/8 to ¼ turn loose).
I’ve scope the cylinders and the reed valves; all good (#1 is spotless like its getting some water in)
I’m just curious if there’s anyone has actual experience with the issue. Please don’t tell me to throw random parts at it unless you’ve actually ran into this problem or run a 2+2.
-jt