Bad Miss

[Outlawzbasser]

I have a 1987 Johnson electric start 25hp motor. It's been sitting for five years, but I'm not sure of the total time. It was on a boat I purchased. I have it running with a bad miss. There is a confirmed spark on both plugs; it is getting fuel. A compression test showed 125 on both cylinders with less than 10% leak down. Will seafoam help? I'm looking for advice on the next steps.

Thank you
Outlawzbasser

 

[racerone]

Could be the classic lean sneeze.-----Open low speed mixture needle 1/4 turn.-----Or if motor sat with fuel the carburetor it might need cleaning.

 

[saltchuckmatt]

I agree, clean carb....I have 4 of these motors.

You can try to backflush the carb but taking it off is better.

Could be the lean sneeze that Racerone is talking about....easy to test.

 

[Outlawzbasser]

Could be the classic lean sneeze.-----Open low speed mixture needle 1/4 turn.-----Or if motor sat with fuel the carburetor it might need cleaning.

Thank you. I will disassemble and clean.

 

[j4jaker]

@Outlawzbasser Did cleaning the carb solve your issue? I am having a very similar issue.

 

[Outlawzbasser]

After performing the carb rebuild and cleaning, the motor sounds great. So yes the carb did the trick. Some fine tuning to do once I get it on the boat.