Johnson 1979 15hp HELP!!!

[rareheir5]

Help I took my boat out today. Fired up ran fine with water bra.Put it in and under a load (river) it would only do about 5 mph after about a mile it all of a sudden kicked in and went full speed until I slowed down and tried to accellerate and back to 5 mph. Maybe these pics will help
thank you in advance for your time and knowledge.
David

 

[fireman57]

Re: Johnson 1979 15hp HELP!!!

Please stay with one post as it is hard for the members to keep up with multiple posts.

 

[mikesea]

Re: Johnson 1979 15hp HELP!!!

Seems like your dropping spark from on of the cylinders,then it kicks back in. Check for coil grounds,leaking spark plug wires,small wire to coil grounding,rusty plug end of spark plug wire, and bad plugs,if the engine has points,change the points and condensers,or better yet convert to pointless ignition,its cheap.