Re: 1974 Johnson 50 hp...no fire on #1
How it works: Magnets passing by coils under the flywheel create electricity that is fed to a capacitor (just one) within the power pack. The capacitor stores that electricity until time to fire (either cylinder). There also are a pair of magnets in the center of the flywheel that pass by a sensor coil. As one passes by, it generates electricity of positive polarity, which is fed to a SCR (electronic switch) within the power pack. That turns the SCR on, which allows the storage capacitor to discharge to one of the spark coils. The spark coil increases that pulse of electricity from the power pack to whatever it takes to jump the spark plug gap. Then it is all over till the next time.
Comes the "next time", the same thing happens, except this time the other magnet passes by the sensor coil, generating electricity of negative polarity, which is fed to the other SCR, turning it on and discharging the storage capacitor to the other spark coil.
Note that:
1. The same charge coils generate electricity to the same storage capacitor, no matter which cylinder is about to fire. So it can't fire one but not the other.
2. There is only one sensor, it's output polarity determined by whichever magnet is passing by. The one sensor triggers both SCR's. The wires connecting it all together are also common to both cylinders. So, the sensor cannot trigger only one SCR. (Unless one magnet was bad, which is unheard of).
2. There are two SCR's, one for each cylinder. So, one SCR, if it is bad, will not fire it's associated cylinder.
See a pattern here? Only the one bad SCR within the power pack, or it's associated coil, can cause loss of fire on just one cylinder. You pretty much eliminated the coil possibility by swapping them. So, logical conclusion is a bad SCR. Entire power pack must be replaced, since you cannot get in it to replace the bad SCR.
Judging the spark by color or sound can be interpreted differently by different people. The spark from those things is very fast and does not have all the harmonics of other systems. Compared to a conventional spark from other ignition systems, it is not as blue. In fact, I would judge it as being white. Ambient light also affects the perceived color of the spark. If you could get a conventional system to make a 7/16" spark, it would be a lot bluer, fatter, and noisier. With all that in mind, I just say it should jump a 7/16" gap with ease and let it go at that.
So...............is your system producing a 7/16" spark off both coils or not? If not, I'd say you have a bad power pack.
EDIT: Let me clarify. There are two SCR's one is turned on by a positive pulse from the sensor, the other one is turned on by a negative pulse. The both are "seeing" both pulses, but only react to the one that has the correct polarity, and ignoring the other polarity pulse.