The coil gets it's power from 2 seperate sources. Pretty much 2 wires coming out of the ignition join together and go to the coil. One of them gives the coil power in the 'start' position, the other gives the coil power in the 'run' position. I would assume either the ignition is stuffed, or a wire has come loose.
I've attached a diagram, and went over the wires in colour which is the ones u need to look at. The yellow one would be the suss wire.
Also here's a pic of the wiring I done in my wags. Take note of the 2 wires on the bottom right of the connector. The wire with the yellow terminal comes around and joins into the terminal next to it. This is not the standard wiring, but those 2 wires are wat feeds the coil (one when the ign is in the 'start' position, and the other in the 'run' position), so they are the ones u need to look at. Also, just incase ya wanted to know, the wire in the middle with blue tape around the end is the power source for the ignition, which goes to a direct 12v source (battery or starter motor[not solenoid]), and the wire up top with the blue connector goes to the starter solenoid so it cranks over. Those 3 (well 4, but one joins into the other) wires is all u need for the carby motors to start and run.....it's simple as!
