1983 90hp misfire under load

[Lonnie5]

1983 90hp Evinrude has a misfire about every 5-7 seconds under load runs smooth under 1/2 throttle. Any ideas?

 

[racerone]

Misfire or jumping in and out of gear ?.----Take cowling off.----Run motor under load.----Observe shift linkage on starboard side of the motor.----Does it move when motor misses ?-----Was the lower unit off ?----Was the shift rod turned ?

 

[Lonnie5]

Thank you will try this this weekend

 

[Bosunsmate]

Look for a spark plug with a different colour of combustion