90 hp merc no get up and go

[tobias30907]

90 hp 2 stroke 2000 merc. Starts and seems to idle fine but engine lags at about 2200-2400 rpms and then tops out at about 3200-3500 rpm. I've checked the plugs, wires, and compression. Engines getting plenty of gas. I've looked at the carbs but am a little lost so I'm not messing with them too much. occationally when running on the water I can get around 5000 rpms but its short lived and then she dies back down to around 3300 rpms. In neutral I can rev the engine and get high rpms but thats it. One mechanic I spoke with said it might be a problem with the electrical time and another mechanic said that the cards needed to be cleaned and sync. Anyone have any input that would be great.

 

[Willyclay]

Re: 90 hp merc no get up and go

Welcome to the forum. First, I am not an expert like so many on this forum but I'm an old guy with some experience with outboards since I was a pup! I just finished working through what sounds like your problem on my neighbor's 2004 Mercury 60HP three cylinder. It was clogged main jets in the carbs. We deteremined that by taking the boat/motor out in the river and after warm-up, tried WOT. When revs peaked at 3000-3500RPM, we pushed the choke/primer button and got instant response from the motor which indicated clogged main jets. We did not have a manual, but his jets were behind a brass hex-head plug on the side of each carb. We did not remove the jets as that required a special tool/screwdriver. We did insert a needle into the jets to free any clogs and then sprayed aerosol carb cleaner through each jet. WARNING: Wear eye protection when you spray because carb cleaner comes out of the intake! That fixed our problem and it is running great now. We also adjusted the carburetor throttle linkage to get the butterfly valves horizontal at WOT. The motor's intake cover had a "link and sync" decal on it. If you are uncomfortable with attempting any of this, get a manual and read up on the motor and maybe you have a neighbor who will work for beer!
Good luck and post your results.

 

[Willyclay]

Re: 90 hp merc no get up and go

FYI, do NOT rev the motor over 1500 RPM in neutral because it is highly likely it will break a connecting rod! Been there, done that.