4 hp Johnson Troubles

[Robj]

Hello,

I was working on a late 1970's vintage Jonhson Seahorse, white in color. It has the built in gas tank and points ignition. Compression on both cylinders is about 110 psi. Both cylinders have spark, and I just installed two new coils. The problem is when running, the top cylinder fires, but the bottom one is dead, it is only running on one cylinder. Anyone have any suggestions as to what could be causing this problem or what to look for. Can't seem to figure this one out. Could it be spark related, it looses spark at higher rpm's? Any other ideas?

Thanx and have a great day,

Rob.

 

[Rick.]

Re: 4 hp Johnson Troubles

I would re-check the coil to plug wire connection. Does it have points? Re-check them if it does. It is possible you got a bad coil but I don't hear of that on this forum, at least not that I remember. You could switch coils and see lf the bad spark follows with the suspect coil. Rick.

 

[Robj]

Re: 4 hp Johnson Troubles

Thanx Rick. When I pull the cord, there is spark to both cylinders. Not sure if the bottom cylinder has spark when it is running. Will check that tommorrow. When I pulled the wire off, I don't recall that there was a spark arcing between the plug boot and the plug. Another thing that I was thinking, it could be the condensor. When those things fail, they do wierd things. Any other suggestions?

Have a great day

Rob.

 

[Rick.]

Re: 4 hp Johnson Troubles

Robj: In your first post you said no spark now you say your not sure. If not sure, pull the top plug while running. If motor dies your right about no spark on the bottom. They do run surprisingly well on one cylinder. They just lack horse power. As I re-read your first post you say very clearly it has points. By all means re-check them if your not getting spark. Rick.

 

[Robj]

Re: 4 hp Johnson Troubles

Hello Rick,

There is spark when I pull the chord with the plug out grounded to the block. When the engine is running, the bottom cylinder is dead, not firing. Since there was spark when I checked it on the bench, I would assume there is also spark when running, but that may not be the case. That is why this is confusing. I will swap ignition components between the cylinders and see what that does, or maybe just buy new condensor since I think that is what is giving me the grief.

Thanx and have a great day,

Rob.