De-Carbonizing an Outboard???

[Mercury60]

Last season my carbs gunked up and made my 1986 Mercury 60hp outboard run like doo-doo. The carbs have been rebuilt and I'd like to get rid of the carbon that I'm sure has gunked up in the motor. I've never done this before but there seems to be two schools of thought:

Method 1:
Get the engine warmed up and spray a de-carbing agent into the air intake. After a little while spray enough in to stall the engine. Let it sit for a while and start it back up to blow out the carbon. Seafoam, Mercury, and others make a sprayable product.

Method 2:
Fill an empty gas tank with 1 gallon of gas, 1 whole bottle of Seafoam, and the appropriate amount of oil. Let it run for 15 minutes and shut it down. Wait 15 minutes and start it back up. Keep repeating until it doesn't smoke.

Which method do you think is better?

 

[lckstckn2smknbrls]

Re: De-Carbonizing an Outboard???

Pour 3/4 of a bottle of seafoam in the tank. put the last 1/4 bottle seafoam in a small spray bottle. Run the motor and spray seafoam in the carb.

 

[narvlebenoit]

Re: De-Carbonizing an Outboard???

#2 works did it to my 90 h.p. inline you should have seen the white stuff on the water at the landing.left the boat on the trailer and used the whole gallon of gas I .would put it in gear once in a while.

 

[hkeiner]

Re: De-Carbonizing an Outboard???

I have tried both methods for decarbing a motor and I prefer Method 1. Method 1 provides more visible smoke when the carbon is being burned off. You can more easily tell when you are done since there is no more smoke once the carbon has all been burned off. I found it to be less obvious when using Method 2.