Thump to kill (1989 25hp Johnson)

[gundy1212]

I have a 1989 25hp Johnson outboard, and it’s having trouble staying at low idle. No matter what throttle I’m at every few seconds there’s a thump noise and the motor jerks, and it drops and then regains rpms, but at lower idle it just dies after one of the jerks. Could this be timing misfire or spark problems?

 

[gundy1212]

Video

 

[flyingscott]

Open up the low speed mix screw an 1/8 of a turn at a time.

 

[racerone]

Perhaps throttle plate is opening too early, or not closed at idle.

 

[gundy1212]

Open up the low speed mix screw an 1/8 of a turn at a time.

Thanks so much dude worked on a full turn out. Must’ve just had the mixture wrong. Thanks so much