Not firing on all cylinders

[rlowhorn]

Have a 70Hp 1980 JOhnson 3cyl. When started and warmed up, at full throttle does not plane out. After running a short distance the other cylinder kicks in and planes out. At home I checked which cylinder by pulling plug wire one at a time. It is first cylinder not firing. What can I do? Is it a coil or what?

[boats.net]

You can swap the coils with #2 cylinder to see if coil works another cylinder.