dada2727 Posted July 7, 2009 Report Share Posted July 7, 2009 I have a 40HP 2 stroke oil injected Merc, it's either a 2004 or 2005 and am having some problems. The problem only occurs at a higher RPM, most noticably at full throttle. When I have it wide open, it seems like it's missing or not firing on all cyclinders (its a 3 cylinder) but I just had it tuned up and the carbs cleaned. It will run fine if I continuously adjust the trim up, down, up, down...and so on, but as soon as I stop adjusting the trim it starts doing it again. I'm thinking it might be electrical because I just spent $350 getting water removed from the carbs apparently. I had this problem a couple years ago and I had it fixed and they told me it was something like a "starter coil" but I'm not completely sure. I just remember they showed me some wires that were melted together. Any thoughts? Link to comment Share on other sites More sharing options...
solopaddler Posted July 7, 2009 Report Share Posted July 7, 2009 Although you said the carb's been cleaned it sure sounds like a gummed up carb to me. I'd try one those carb cleaners that you mix with the gas. That's worked for me in the past... Link to comment Share on other sites More sharing options...
ohhenrygsr Posted July 7, 2009 Report Share Posted July 7, 2009 so with the miss firing does it still run or just die out? Link to comment Share on other sites More sharing options...
dada2727 Posted July 7, 2009 Author Report Share Posted July 7, 2009 still runs, never stalls or anything...just sounds like its missing. Any recommendations on carb cleaner additives? Link to comment Share on other sites More sharing options...
Fisherman Posted July 7, 2009 Report Share Posted July 7, 2009 Seafoam! Should be able to get it at Carquest or NAPA. Sounds like a Stator coil, makes power.. Link to comment Share on other sites More sharing options...
Sinker Posted July 7, 2009 Report Share Posted July 7, 2009 Its funny you post this, because my 2 stroke 40 mariner started doing the same thing. Only at WOT. I can run 3/4 throttle no problem, but as soon as I crack on it, she misses. I have no idea what it is. I was going to post the same question.......it will idle, troll, run at any speed but wide open no problem. As soon as I crank it open it misses, so I back off. I don't think running seafoam is going to help, I run it in every tank of gas, and I decarb it a few times a year too. She's as clean as a whistle, and the carbs are mint. I almost thought it was starving for fuel at full throttle? S. Link to comment Share on other sites More sharing options...
Garnet Posted July 7, 2009 Report Share Posted July 7, 2009 Try pumping the fuel bulb when wide open might be just losing pressure. Garnet Link to comment Share on other sites More sharing options...
fisher Posted July 7, 2009 Report Share Posted July 7, 2009 Are you using fuel without ethanol...? I swear the issues I had with my 2 stroke 40 HP Merc all started when ethanol was introduced to gas. Since I had it rebuilt, I have switched to the highest octane gas from Esso, Petro Canada or Shell who do not put ethanol in them (they only put it in their lower grade fuels). Link to comment Share on other sites More sharing options...
ohhenrygsr Posted July 7, 2009 Report Share Posted July 7, 2009 Are you using fuel without ethanol...? I swear the issues I had with my 2 stroke 40 HP Merc all started when ethanol was introduced to gas. Since I had it rebuilt, I have switched to the highest octane gas from Esso, Petro Canada or Shell who do not put ethanol in them (they only put it in their lower grade fuels). I have only found that Shell and Ultramar High test have no ethanol never heard that Esso or Petro didn't have it either Link to comment Share on other sites More sharing options...
fishermccann Posted July 7, 2009 Report Share Posted July 7, 2009 I agree put in super gas , no more problem. Link to comment Share on other sites More sharing options...
dada2727 Posted July 7, 2009 Author Report Share Posted July 7, 2009 Well apparently it was just a spark plug, but we'll see. If it is, I feel kinda stupid but before for some reason I don't think it will be the end of it. Thanks fisherman, the Stator coil was the part I was thinking about that I replaced last year, some wires were melted together. To be continued........ Link to comment Share on other sites More sharing options...
Fish4Eyes Posted July 8, 2009 Report Share Posted July 8, 2009 Doesn't high octane gas make your engine run hotter? Is this recommended by marine mechanics? Link to comment Share on other sites More sharing options...
fishermccann Posted July 8, 2009 Report Share Posted July 8, 2009 it has no alcohol to attract the water. Link to comment Share on other sites More sharing options...
dada2727 Posted July 8, 2009 Author Report Share Posted July 8, 2009 How many people just run regular fuel? Link to comment Share on other sites More sharing options...
Fisherman Posted July 8, 2009 Report Share Posted July 8, 2009 Me, in everything unless the mfgr specifically indicates a higher octane requirement. Google what octane actually does in the combustion cycle of an engine and what kind of motors it is intended for. Link to comment Share on other sites More sharing options...
danbouck Posted July 8, 2009 Report Share Posted July 8, 2009 I use regular and add stabil ethanol treatment Link to comment Share on other sites More sharing options...
Sinker Posted July 9, 2009 Report Share Posted July 9, 2009 I use regular and add stabil ethanol treatment Ditto! My problem was a bad o ring on the fuel filter cansiter. So far so good. If I pumped the ball while going WOT she ran fine, so I started at the tank, and worked my way back to the carbs and found the split O-ring. S. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now