1983 Johnson 25hp firing only one cyl

[66mstgfsbk]

I have a 1983 johnson 25 only firing one cylinder. I swapped the wire to the coil pack just to check for spark and I have spark. It is the bottom coil that is not firing. When I put the wires back to the original location the other one fires just fine also. I checked the stator according to cdis instruction and it checked within spec. Does this sound like. Bad power pack?

Just changed both plugs, rebuild carb, rebuild fuel pump, will be doing t'stat and impeller after I find ignition issue. This is a rope start engine.

Thanks for any help

 

[racerone]

Re: 1983 Johnson 25hp firing only one cyl

Are you saying that the bottom cylinder has no spark?---- Or when you pull plug wire off there is no difference in the performance of the motor ?----Does bottom coil spark when you install it for the top ?

 

[66mstgfsbk]

Re: 1983 Johnson 25hp firing only one cyl

Are you saying that the bottom cylinder has no spark?---- Or when you pull plug wire off there is no difference in the performance of the motor ?----Does bottom coil spark when you install it for the top ?

The bottom cylinder has no spark at all I check with a tester. But what I did was switched the orange wires to test the coil. Yes I am aware that it changes the firing, but wanted to check for spark. When moving the orange wire from coil to coil the other will spark and leave the other dead. So I think the power pack has a dead spot preventing one pack ,which is the lower one the original one that did not fire. Is that possible? Thx

 

[kbait]

Re: 1983 Johnson 25hp firing only one cyl

Yes, CDI box can lose impulse to just one coil. I've seen it a couple times.. normally they just all-out fail.

 

[M Strawn]

Re: 1983 Johnson 25hp firing only one cyl

Does yours have an over rev limiter /over speed protector? I had a Johnson 40hp that dropped a cylinder due to a faulty rev limiter.

 

[boobie]

Re: 1983 Johnson 25hp firing only one cyl

Sounds like a bad power pack.

 

[66mstgfsbk]

Re: 1983 Johnson 25hp firing only one cyl

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Does yours have an over rev limiter /over speed protector? I had a Johnson 40hp that dropped a cylinder due to a faulty rev limiter.

None that I know of. We were givin a 14 foot alum and this engine from a neighbor that wanted it out of his driveway. But the engine hasn't ran in years. So I did all the basics and fired it to check for sounds and operation and that when I noticed only running on one cyl.

 

[66mstgfsbk]

Re: 1983 Johnson 25hp firing only one cyl

Sounds like a bad power pack.

That's what I'm thinking but not 100% sure. I checked the parts under flywheel and the ohms are within spec according to cdis specs.