Lost spark mid run

Sorry for posting again but I feel like the issue may have changed enough that it garners a new thread.

1977 Johnson 70hp:

I had chased down an electrical problem to faulty wiring on the control box side of things and got that all tidied up and reinstalled and everything was working as it should. As I was taking a lap around the lake everything was running great with zero signs of any trouble when all of a sudden the motor shut off like I hit the kill switch again.

This first thing I did was pull the kill switch wire from the powerpack to see if the switch had again failed on me but still no spark even with the switch bypassed.

The starter is cranking just fine just no damn spark again. From what I’ve been reading it seems like it may be a bad powerpack but I’m unsure of how to diagnose that. What do I start checking at this point? I’m kind of lost here.

By "kill switch wire" I assume you mean the black/yellow wire... also I assume by your wording that you have already replaced the ignition switch. If so, check the ground wire leading from the p/pack to the powerhead for a proper connection.

Visually inspect the stator for a meltdown of the 3 large evenly spaced coils which may be dripping a sticky looking substance down on the timer base and powerhead area. Combined, they supply the needed power to the powerpack capacitor. A meltdown causes that power to drop resulting in what you describe.

Other than that, I'd suggest replacing the powerpack. Even if the new powerpack doesn't cure the problem, having a spare one and the tools to replace it in your boating tool-pack is good insurance.

Thanks so much for your quick and knowledgeable response! Yes, the black and yellow wire, located on the lowest left spot on the block. You are also correct in assuming that I replaced the ignition switch. Planning on going over the wiring on the powerhead with a fine tooth comb shortly. I lost daylight yesterday when it stopped running so I was unable to really take a good look at everything.

To be perfectly transparent, my wiring job was far below subpar getting the ignition switch in. The original wiring was crimped through in several places so as a quick fix I just spliced in small replacements for the crimped bits. It's messy to say the least. I plan on trimming back the harness and putting fresh terminals on everything today.

I am under the impression I will need to remove the flywheel to check the stator? Is there a way to check the voltage coming into the power pack that would allow me to get an idea of the state of the stator without visually inspecting it? I am 100% willing to do what I need to but I am pretty inexperienced and lack the proper tools to pull the flywheel.

I will be ordering the powerpack today for sure regardless of what's going on.

Thanks again for your response!

The stator can be checked easily as is simply by looking under the flywheel with a strong flashlight. If any of the three "Powerpack Capacitor Charging Coils" have started a melt-down process, you'll notice a sticky looking substance having dripped down from that green stator onto the timer-base and/or the powerhead area. No need to remove the flywheel for that visual.

To replace the stator... yeah, pretty sure that flywheel will need removing.

That flywheel nut torques to exactly 105 ft lbs. Don't guess at it!

Got the new power pack in this evening. Working great again! Thank you so much for your help! Man I sure love the way this girl sounds when she’s running! Absolutely love the sound of an old 2 stroke!