I have a 1977 Evinrude 85hp which only has one power pack. I had a similar problem so I swapped the sensor wires (2 for 2) on the power pack and found that the spark was still good on the same side, so I am reasonably sure I have a bad power pack.
An old reply I know, but your information was useful to me, so this might help some one else. I have a 1977evinrude 85 hp with exactly the same problem, but possibly a different cause. Swapped the coils - no change. Swapped the sensor wires - still no change. Every thing points towards the power...
