My Motor Died...now wont start...

So after a near two month process of rebuilding my 30 year old tin, I had a GREAT weekend boating and fishing. My happiness ended when I went on a solo trip yesterday. Before I left the house on Friday, I cleaned out the tanks, replaced everything with new oil and gas, and went on my merry way. The first launch was eventless, motor started right up, and the boat went great!
Yesterday, a few hours of use later, I finally ran the first tank dry. The motor died after sputtering. No big deal I said...I have an extra tank! I swapped the hose over, primed it up, and turned the key...nothing. Thankfully I was near my father-in-laws camp along the brook. I tied up to avoid drifting down stream too far. I tried everything I could think of. I pulled the spark plugs out, they were saturated with gas/oil. I cleaned them, let them dry off, and plugged them into the plug wire. I turned the key and no spark. I was quite upset...and somewhat stranded to boot.
I did some checking and found that all the wires were connected tightly, no loose ends, no shorts that I could see. I wiggled and tugged gently to make sure. Still no spark. I have no cell service where I am...enough for a text message thankfully. I fired off a message to my honey (HELP ME!) I was stuck. I remembered that father in law had a trolling motor, so I went up and got that out, hooked it up, and thought...hmmm, I wonder if I can make it...it was a bad idea from the start. I paged my honey again and she answered, she was on her way.
I randomly turned the key to start the motor, and vroom...it fired, sputtered, and died again...I changed nothing...
I have read about the stator assembly going bad, the rectifier going bad, and the coils going...I hope its easier and cheaper than that...

the motor is a 1974 Johnson 70 HP, electric start. I appreciate any ideas and input, thank you!!!! Bob

Sounds like what happened when I ran my tank dry on my old Chrysler. After letting it crank a looooong time it finally started. Mine ran good once it finally fired though. I would make sure of the obvious first like having the vent opened on the tank and the primer nice and firm. Otherwise I would look into the fuel filter to make sure it didn't get gummed up from something in the bottom of the tank. Does your starter utilize a solenoid? If so that might need changed? Mine has a starter circuit breaker as well that I had to reset once in order for the starter to fire.

So, thanks to a few folks, and some helpful web sites, I found the issue. I did some troubleshooting, had no spark at all. Check the coils, check the stator, everything....The last thing to check was the ignition kill circuit. Removed the lead from the terminal, turned the key, and VROOOOOOM...off she went.

Only problem now was that I could not shut if off without making that connection again...CAUTION**** 20,000 Volts is more than a tickle!!!!!

Rigged a switch to get me out of my jam, and tested it a few times, worked like a champ! Boat should be out of the water and on the trailer tomorrow, only to launch again a few hours later.

Just want to say again how AWESOME you guys are on tin boats!!!!! I'll post pics of the maiden voyage today!

Glad you figured it out! It is never fun to have a problem that needs a lot of diagnostics.

OEM Manual called for a neon test block...never even heard of one! I got lucky, glad I did but lucky non the less.

Well, it's not quite 20,000 volts......more like 300 but it does hurt like Hell ! Chances are the back of your key switch has a visible carbon track to the ground terminal on it. New style OEM switches have a raised boss for that black/yellow terminal to eliminate this from happening.

Thanks Pappy, i'll be looking this weekend. I think I screamed and cursed 20000 times...YEOUCH!

Thanks!!!

Bob