I am confused. A flame thrower three is a module for Computer controlled late model cars. Do you mean an Ignitor III?
The pink wire is to reduce the voltage to the coil to about 6 volts during normal running. The wire from the I terminal jumps this to supply 12 V only for starting. If you run 12 volts to a conventional coil full time the coil will burn out. Normally, with full 12 volts,the coil will become intermittent as it gets hot, (possibly what you thought was a bad ignition switch) and then fail completely. To test the coil, remove all wires from the coil. Take the center wire that goes to the center top of the distributor and plug it on top of a spark plug. Rest the spark plug on the block. Take a wire and connect it to the plus side of the battery and the plus side of the coil. Take a wire and connect it to the negative side of the coil (the one that goes to the distributor points). Take the other end of this wire and quickly touch it to the engine block or negative terminal of the battery. Every time you touch it, you should get a spark at the plug. If not, the coil is fried.
Most aftermarket coils such as Accel, require the use of the pink wire and an extra supplied resistor. I believe Petronix requires the pink wire unless you have one of their systems with a current limiting device.

 

Actually, many higher end aftermarket performance coils require a full 12V supply. This is the only way they can make their advertised secondary voltage. They may operate on lower primary voltage, but not at the advertised secondary voltage. For example, the MSD Blaster II and many of the Pertronix Flamethrower coils want a full 12V supply.

 

I'm having the same issues. 65 289 C4auto. Ran when I got it back out, like crap. Dumped a bunch of $ on it, new hoses, battery, coil, cap, rotor, plugs, wires, coil, rebuilt carb and adjusted, fuel pump, filter, odds and ends. Would run but still bad. Found my distibutor bearing was whopped out. Got a new replacement points distributor, fired right up and idled better than ever, set the timing at idle then soon as I pulled out and gassed it fire went out. I have had NO spark since. I have 12V on both sides of the coil but read I should only have 6-9V on one side through the pink resistor wire? Please help I'm in over my head at this point! Electrical on this car is hacked.

 

With the ignition on and the points open you will probably have 12 volts on the coil plus side and about 12 volts at the arm of the points. With the points closed you should have about 6 volts on the coil plus side and 0 volts on the points.. Recheck the point gap first. Make sure it is gaped on the distributor cam high points. Then have someone crank the engine while you watch the points open and close to insure the distributor is a) turning and b) the points are opening and closing. Replace the condenser with a new one. Pull a spark plug wire and put it into the center terminal of the coil. Put the other end on a plug and rest the plug on the block. With someone cranking the engine, the plug should fire 8 or 6 times per engine revolution. If the plug does not fire the coil is shot or you have grease on the points or a bad wire to the distributor from the coil or a bad ground from the block to the battery.