What would cause a 1981 Ford F-250 not to fire when you turn the key but it fires after you let go?

Answer 1

you have the ignition coil wired wrong you need to have 12v during crank and after to. sounds to me you have it hooked up so when your cranking it over its cutting out the 12v its like when you start your car and the radio shuts off till your done cranking it over well that what happens when you wire you coil up wrong...

It has a bypass to the ignition that gives the coil 12 volts when starting and goes to about 8 volts when running. The bypass wire is not conected or broken