Quote:

You mentioned the ECU is mounted under the dash?
Could it be getting power from the ACC side of the fuseblock, and not from the run side of the ballast resistor as is the normal wiring configuration?



Try this test to verify if the ECU is wired to the ACC power.

#1 - disconnect the starter relay spade connector so the engine/starter will not spin when putting the key in the "start" position.
#2 - put key in the ACC position.
#3 - Jumper a wire from the battery positive to the ignition coil "+" terminal.
#4 - use a starter switch or wire from the starter relay spade connection to the positive post of the relay to start the car.

I think the car will now start?

With the engine running, and the starter wire still disconnected from the starter relay so the starter will not engage, turn the key to the "start" position and hold it there. If the engine dies, you just verified the ECU is on the ACC circuit, not the RUN circuit.

When the key is in the "run/on" position you are powering the Accessory circuit (radio, ect), and the engine compartment run circuit (Normally power to the ECU, alt field, voltage regulator, ballast resistor and carb choke heater if equiped.)

Because the ECU was moved to a non-stock location, it may be wired to the wrong power circuit.