I have worked on all types of equipment from cars to lawn mowers to heavy equipment for 20 yrs and I'm stumped on a 2 stroke boat motor! PLEASE HELP!  My motor is old but has great compression and new plugs fuel and everything else I could possibly change as rotine mantainence. my problem is I'm only getting fire on 2,4 ,and 5. The other three are'nt hitting and Ive ohm'ed out everything I could check acording to the book. Everything checks good and I know the motor runs. I've started it but it would'nt idle. Had to run fast and I know you should'nt run it fast out of water so I'm now trying to get it exactly right and this is what I've found. Can anyone give me a new direction?  PLEASE!  I got the fishing fever and my boat is down!  Thank You!

I feel your pain, same thing was happening to my 40 horse this summer. Finally had to take it in. The problem was a gummed up carb and a lot of water in the fuel. Turns out adding fuel stabilizer isn't a guarantee you won't have water separation because of the ethenol. It was worse this summer because of the high heat and humidity by me and I didn't use the boat as much so the gas just sat there. Maybe this will help you. Good luck.
Lee

i've got a 1986 115 merc and have had some problems as well and last year had to have the ID boxes replaced. i think i have that correct. there are two of them as each ID box powers 3 cylinders.i was out with it last year after having replaced the one IDbox and it was running great and in a second something went wrong and it wouldn't run fast, but would idle.it was the other ID box that went out. was told that when replacing one,do them both.hope you get it figured out.