120 Johnson,Once again,best decarb method

[mrtool2u]

I just picked up a 1993 Johnson 120,and I want to decarb it.This motor spent it's time on a 7000 pound houseboat,so I assume it need's a good decarb.I know this topic has been beat like a rented mule,,but I want the best for my new outboard.What is the best decarb,,,i can get Seafoam locally,,OMC tuner is within 30 miles.Better to use the spray(motor has the valve on carb's)or the gallon of gas/oil with the pint of Seafoam. If I use the gallon of gas,would it be OK to do it in a barrel,let it sit overnight,then take it out the next day.Any and all info appreciated.

 

[ob]

Re: 120 Johnson,Once again,best decarb method

I personally like using the OMC engine tuner through the schrader fitting on the primer solenoid used as per instructions on can.Then give her a good run in the water the next day.Also ,good idea to inspect and clean sparkplugs after the procedure.

 

[Solittle]

Re: 120 Johnson,Once again,best decarb method

Might want to do a compression check before you do anything else to get a sense of where your motors is at.

 

[mrtool2u]

Re: 120 Johnson,Once again,best decarb method

Actually,before i would buy the motor,I made the guy start the motor on muffs,and did a comp check,around 145 all cyls.My gague seems to read a bit high,so I assume 135 is more realistic.The guy has never did a decarb,so I figured it would be a good idea.

 

[mrtool2u]

Re: 120 Johnson,Once again,best decarb method

Hey OB,,if you do use the schrader valve,do you need to move the red lever.

 

[ob]

Re: 120 Johnson,Once again,best decarb method

Just leave the red lever in the normal 'run' position.All of the injection specifics are on the can.One two second burst for each cylinder waiting two seconds between bursts.The a final burst for 20 secs "no more" or until engine dies.If engine doesn't die ,don't exceed 20 secs on the final burst.Let sit 3 - 16 hours depending on the suspected carbon buildup and then give it a good run in the water.Engine should just be warm at idle while performing the decarb.