No Spark while Cranking. Engine starts when key is let go.

There are two circuits for ignition. One is the normal that goes threw your ballast resistor when the key is in the run position. The other bypasses the resistor block and gives a full 12 volts to the coil to aid for the loss of volts during cranking. This is only on when your key is in the cranking position. First place is to look is the hot wires on the ballast and start tracing the wires. Those should be the two blue wires.