40 HP Carboned Up

[jim.walters]

I have a 1992 40 HP Mercury 4 cylinder 2 stroke. When I bought it it would not run fast. About 2200 RPMs. Low speeds it worked great. After many part replacements from a mechanic that did not fix it I brought it to another dealer. They tested everything. They found that the exhaust manifold was plugged with carbon. It was a lot of carbon. If you rolled it into a ball it would be about 8 inches around. After that the motor ran great for about 5 runs. Now it seems to not be very quick out of the hole, a slight hesitation, then it planes off and goes fast. When running at full throttle it seems to vary in rpms a little, maybe 200 rpm's, and you can hear the fluctuation. It seems that everytime I take it out it is getting a little slower. I have changed the computer, fuel pump, spark plugs, had the carbs cleaned, compression tested, spark tested. I am having trouble trusting this motor.

 

[Fouled Plug]

Re: 40 HP Carboned Up

Mercury makes a neat product called Power Tune for decarbing outboards. It comes in an aerosol can, and is easy to use. You may want to check it out.

 

[KennyKenCan]

Re: 40 HP Carboned Up

Do like Fouled Plug said.<br /><br />Although there are other products out there that do the same as the Merc stuff.

 

[jim.walters]

Re: 40 HP Carboned Up

Tried the Power Tune. Did not clear it up.<br />I have dropped it off at the dealer and will let you know what they find.<br />Thanks for the help.<br />Jim