No spark on one cylinder while cranking.

[hardwater fisherman]

Evinrude 40604R. Some history. A month ago on the lake I had a hard time starting and when taking off I could tell it was only running on one cylinder. Then it started to run on both for the rest of the day. The next time out it started and ran good first thing. But later in the day it was dropping in and out at low speed and hard starting. It would catch and go with increased RPMS. I have tested the driver coil it is within spec. I have 3 external coils that read the same and all produce good spark on top. New points clean and gaped. New condensers. I have checked all wires related to the bottom cylinder. I have tried 2 different cut out switches and the safety switch that goes with it. The safety switch works because I tried it in place of neutral safety switch and the motor cranked. The top lead jumps at least 3/8 or more while cranking and the bottom only barely jumps the plug gap in open air. I am running in a barrel right now and when it does start it is only running on top. Some times if keep the throttle on it will "grab" on the bottom and rpms will increase but if I let off it spits out the exhaust and dies. This is what it was doing on the lake but once in gear and with increased rpms it would run on both. I have had the flywheel off so much that I dont need a torque wrench, I can do it by feel. EDIT I should ad I have new plugs gaped at .030. Also new high tension leads, boots and the little spring things that fit over the plugs.

 

[hardwater fisherman]

For some that do not know this is a rope start motor converted to electric start. Which has run well for 4 years since the conversion.

 

[kbait]

Your motor is a '76. If the armature plate has any lateral play, it'll change point gap, and run poorly. If no play there, check entire kill wire from bottom cylinder, button to point set. Also confirm good ground strap/connections from armature plate to power head. If that's all good, swap condensers and test spark. If still weak on bottom, switch pointsets and test again. No change, swap coils and test again (good clean ground connections). It's not the charge coil under flywheel, as that supplies both coils.
You'll find the issue..hang in there!

 

[hardwater fisherman]

The mag plate has a tiny bit of movement but I think it is ok. I have switched the points and the coil that is on the bottom right now works on the top . I made the wiring harness because the old one was toast. But I was also thinking about the kill wire also so thanks. I will check that out. I just got back from the hospital and I have shingles, and not the type you put on your roof. This the 5th time in 12 years I have this. 3 times in the last 2 years. I have had the vaccine 2 times and it did not take. I have not missed one minute of work though. Got to go back to work on labor day. Maybe tomorrow I will take another look at it.

 

[gm280]

Oh WOW I know all about Shingles and not the type that goes on the roof as well. I had them once and don't want them anymore. Between Lyrica and Celebrex it finally worked out. Take care and I feel your pain. :sorry:

When your engine drops a cylinder, have you swapped the spark coils to see if the problem follows the coil? That is the easiest first procedure you can try without removing the flywheel. If the problem is still on the dropped out cylinder and you know it is actually a lack of spark, then you need to go into the ignition system under the flywheel. JMHO

 

[hardwater fisherman]

My doctor told me that I should only get it once but in rare cases it comes back. It is nasty for sure. This time and the last it is only in a small area so it is not too bad, but 2 years ago it was half way around my body. Regarding the coils I have 3 coils that work on the top so they should work on the bottom also. But yes I have swapped them. Last time on the lake I went up on the side and swapped them and had the same result. Spark only on top at low rpms.

 

[gm280]

My doctor told me that I should only get it once but in rare cases it comes back. It is nasty for sure. This time and the last it is only in a small area so it is not too bad, but 2 years ago it was half way around my body. Regarding the coils I have 3 coils that work on the top so they should work on the bottom also. But yes I have swapped them. Last time on the lake I went up on the side and swapped them and had the same result. Spark only on top at low rpms.

Well I surely hope I never get them again. Painful is an understatement.

As for the spark coils, Since you have swapped all three into a working cylinder, then they are out of the equation now. So you have to work backward from there. And that leaves points and condensers. You can easily check condensers by simply disconnecting them out of the circuit to try. Don't leave them disconnected but for testing. Because they are there to help keep the points from arching over time and burning the point contacts. Which leads me to another idea. Have you cleaned up the points themselves? You can take some fine sandpaper, like 600 grit, and sand the surfaces and then use contact cleaner or something equivalent maybe Acetone or Lacquer Thinner or even Alcohol to clean them off. Could be the points have some film on them and stopping spark occasionally. ANd make sure to regap them at 0.020" again. Just an idea. :noidea:

 

[hardwater fisherman]

It is a new tune up kit and yes I lightly sanded and cleaned the points. The condensers are new but I guess one could be bad.