[Yeager]

I have a 74 911 S with a Permatune CDI, Bosch coil, and Pertronix electronic ignition.

I am not getting a spark from the coil.

However, if car sits overnight it tends to fire right up but after a minute or two dies and will not crank again.

I have performed the coil ohm test and it is good. I have checked the supply voltage to the CDI and it is good. I have checked the resistance of all of my wires and they are good. I have checked and rechecked for ground loop problems and cannot find any. I have pulled on wires to try and find shorts and have found none. I have removed the CDI box and performed ohm tests and it is good - as far as I can tell. I have removed the relay panel and looked for bad connections and have found none. I have also disconnected the black/violet tach wire and nothing changed. All other electrical items work well. I have never had an issue with the starter not turning or any other electrical issue that would indicate a ignition switch problem.

Two things that I have not checked and would like to know how are:

How do I check the signal from the petronix ignition to the Permatune CDI (3 wire)?

How do I check the voltage to the coil when starting? I have checked with the ignition on and it has good voltage to the A terminal.

Also, I do not see any external ground wire on my distributor. Is this normal?

Thanks for any help. I have spent countless hours reading and testing without any progress.