Electrical Demon?

This MAY NOT be electrical, I'm not convinced either way. After the engine died, did you notice whether the carb accelerator pump would show fuel? That might have indicated a fuel problem


Both the ECU and regulator MUST be grounded, no matter what. Make sure you are stabbing through paint, chrome, rust, etc with your probe. Anyplace on the ECU or VR shell should be ground

It's not clear to me that you are or are not getting spark.

Is this a 4 or 5 terminal ECU? This is IMPORTANT because the newer 4 terminal ECU only needs a 2 terminal ballast, and can make troubleshooting that much easier.

Not all 4 terminal ECUs have 4 terminals. The 5th terminal may be a dummy. If it is NOT a Mopar OEM branded ECU it probably is NOT 5 pin regardless of pin count. Only way to tell is to resistance check the 5th pin to all the others, reverse your leads, and try again, to see if ANY of them show anything other than infinity. Also check to ground.

As Red said, I would pull ALL connectors and give them the wiggle test.

With the key in "run" ground first one, then the other distributor harness wire leading to the ignition. One or the other should produce one single spark when grounded.

With the key in "run" engine off, coil + voltage will be somewhat low, anywhere from 6-9 volts perhaps. If this voltage is near 12V check the NEG coil. A high reading there means the ECU is NOT grounded or is bad.

Probe the ballast for the "high" (KEY) sided, and check that carefully against battery voltage. When you find the high side, move your ground probe to battery positive. This will give you a very low reading, the lower the better. More than .3V (three tenths of one volt) means you have excessive voltage drop in the wiring between battery, switch, bulkhead, etc on the road to the ballast.