1974 johnson 40 hp new coils rand good; now not so much....please help

[stemper57301]

Hello,
I have a 1974 johnson 40 hp outboard. 2 weeks ago I replaced both coils since they were cracked and old. Motor missed pretty bad before and had nothing at WOT. After I replaced the coils in ran great, 30 mph wot on my local lake. Well that lasted for about 2 weeks and now back with same problems. At WOT she wants to die, like its flooding or something and has no top end. Also has the miss again. My question in that when I UNHOOK the lower spark plug wire from the plug it runs good, no miss or anything. Why does it do this? Also could the bottom new coil be shot already? Any ideas are greatly appreciated. Thanks

 

[somesaytim]

Re: 1974 johnson 40 hp new coils rand good; now not so much....please help

Let me know if you figure it out I have the same engine and same problem...will let you know if I figure it out first.good luck

 

[stemper57301]

Re: 1974 johnson 40 hp new coils rand good; now not so much....please help

Let me know if you figure it out I have the same engine and same problem...will let you know if I figure it out first.good luck

Tim, what have u tried? I have done a complete carb rebuild, new coils, new impeller and wear plate, new spark plugs, pulled flywheel and checked gap of points. I'm currently putting new points because the cylinder that stumbles points looked corroded and worn. So I have ordered new points, new coil and lamination for under the flywheel and I'm rebuilding the carb again. Should be done in a week ill let u know how I fare.

 

[bonzoscott]

Re: 1974 johnson 40 hp new coils rand good; now not so much....please help

Not sure about all that you describe, but I'd hold off on carb build until you try new points. It sounds like running on one cylinder and points may be all you need.

 

[stemper57301]

Re: 1974 johnson 40 hp new coils rand good; now not so much....please help

Not sure about all that you describe, but I'd hold off on carb build until you try new points. It sounds like running on one cylinder and points may be all you need.

Scott,
I tried to upload a picture of the points too see what you thought but can't get it to upload. So would the points cause the intermitent problem? Like I said after I put new coils on she buzzed around the lake like a dream, than 2 weeks later back to the aame problem. Another thing it does is when I give it fuel and try to go to WOT it falls flat on its face like the timing isn't advancing. Any help is greatly appreciated.

 

[somesaytim]

Re: 1974 johnson 40 hp new coils rand good; now not so much....please help

I have replace coils,points,condenser.had intermittant spark at first now no spark?...goodluck

 

[geoffwga1]

Re: 1974 johnson 40 hp new coils rand good; now not so much....please help

Sounds like you have a ground somewhere between the points and the plug.Check leads for worn or chafed spots,the wire does not have to be bare for it to arc.Check also the little ground wire between the coil and the points.
Geoffwga1

 

[CrawlHer]

Any new news on your motor? How does it run now?