I agree with the previous reply about the ignition switch and bulk head connector. It might also be the connector under the steering column. The ignition switch has 2 different circuits for feeding the coil, one in the run position, and another in the start position. The start position circuit bypasses the ballast resistor (and feeds 12V directly to the coil) during starting. When it won't start, disconnect the battery and use an ohmmeter to measure circuit resistance from the + battery cable to the + coil terminal (with the switch in "start" position). You will probably measure high resistance. Wiggle the connectors and switch until you see a normal low resistance. That will indicate where the problem is. Good luck.