68 Evinrude 55hp burning out coils

[northface]

I have a 1968 55hp Evinrude I rebuilt a few years ago. I put in a new power pack, coil, points, wires, plugs... It runs perfect for a while and then starts to break up or become hard to start. Each time it appears to be the coil. One of the new OEM actually developed a crack. Any idea why the coils would keep going bad? I've tried using both the original and replacement OEM coils.

Oddly, the originals will start but then develop a bad miss. The OEM will always run well one started but begin to make it harder to start until they go completly bad.

 

[boobie]

Do you have copper wire plug wires ?? You may want to run a continuity test with an ohmmeter on all the plug wires.

 

[northface]

I'm not sure.I'll check the continuity but they are new wires.

 

[northface]

Good continuity across all the wires. Just checked the coil (which is only a few weeks old) and it's got ~100ohms across the condenser and ~800ohms across the secondary. Pretty sure I should be getting 0 and 3-8k respectively. So I'm convinced it's cooked same as the last one. But no clue what's causing it.

I did connect my stator to the tachometer (which is not working properly). Not sure if that could have anything to do with it.

 

[Tim Frank]

That's the TR-10, I had that model for 35+ years.
At about the 30 year mark I had a lot of ignition issues and it developed an appetite for some of the expensive ignition components.
I traced it to deteriorated primary wiring under the hood.
I replaced it all and the engine never ran better.

Do a good visual and tactile inspection. The insulation tends to just disintegrate when ouched.

http://forums.iboats.com/forum/engi...de-outboards/288586-1969-55-hp-wiring-harness

 

[northface]

It's actually a 55872R. But pretty much the same. You're right, a lot of the wiring was dry rotted when I got it. Much has been replaced along the way but not all. Sounds like a good winter project.

Any advice on what type of wire to use? I'll probably take it right down to the lower unit. It's a electric shift. Not sure if anything shorting down there could cause it but if I'm going to spend time/effort rewiring I might as well go the distance.

 

[Tim Frank]

Ummm....not sure how i missed "Evinrude".....:sleeping::facepalm:

But yes, same motor essentially.

If you check that link to a post, you'll see that I reused the "excess" wire from the original wiring harness. It has been wrapped in that heavy rubber sleeve and was in perfect shape. The wiring harness has at least an extra few feet unless you have a 20' + boat.