I feel like I am running around a bit here...totally my fault. I made an assumption that the power into the bulkhead was adequate. I just found that it is only 10.3V when cranking however the voltage at the starter relay drops to 10.3V when cranking too. The battery is new. Maybe this is normal? This explains why the power is only 8-9V at the coil cranking. There must be nothing wrong with the wiring at the bulkhead and ignition switch. With the engine running I see the voltage across the coil is under 5V today. The voltage at the resistor is 14.6V in / 7.5V out with the engine running. I am losing almost 3V between the resistor and coil. I believe the wire runs directly from the ballast resistor to the coil. I'll have to investigate.
What should coil and ballast resistor voltage be?
- Thread starter 1MeanA
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Perhaps this coil voltage issue is a red herring. If I go back to the beginning the car was hard to start when hot. I mentioned it (albeit in another post) that it seemed like it started when I let go of the key. Perhaps it did this reliably when cold but not when hot. I dunno. I dug out my spark tester and see that even when fairly cold there is no spark when cranking but spark when I let go of the key as the engine fires. 
I'll have to think about where to go from here. I don't have a spare ECU. I do have a ground wire from the ECU to the firewall.
I'll have to think about where to go from here. I don't have a spare ECU. I do have a ground wire from the ECU to the firewall.
Go back and re read his post #11 and see if that helps.
I'm not help. I am so simple minded I still use points! That way I can never blame any issue on the ECU!
Voltage drop at firewall connector? I am so old and so not a purist, I have drilled thru the firewall connector and ran said wire directly in/out!
Some of this almost reminds me of the "bad ballast " thing. That Mopar fires up and runs with Ign.2 but soon as you release the key, it dies! It got full current in "start" and thus fires up and runs, but nothing afterwards in "run" to keep running.
Yes I am little help with electronics.
I'm not help. I am so simple minded I still use points! That way I can never blame any issue on the ECU!
Voltage drop at firewall connector? I am so old and so not a purist, I have drilled thru the firewall connector and ran said wire directly in/out!
Some of this almost reminds me of the "bad ballast " thing. That Mopar fires up and runs with Ign.2 but soon as you release the key, it dies! It got full current in "start" and thus fires up and runs, but nothing afterwards in "run" to keep running.
Yes I am little help with electronics.
This part?
I can check voltage to pin 1 on the ECU when cranking. I'm a mechanical guy not electrical. Give me a break
The coil negative is switched to ground but it is not AT ground. With breaker points, they have resistance, and duty cycle. With electronic ignition, the negative is likely 1 1/2--2V above ground. This is because of resistance through the switching transistor in the ignition box, which can not be improvedWhat's the difference between voltage across the coil and voltage from coil + to ground? I get 3V lower across the coil vs coil + to ground. Me and electricity don't see eye to eye
Actually since you mentioned that, we had one guy where th ECU had one wire that was a poor connection to the ECU terminal, right at/ in the ECU connector itself. ANY wire/ terminal connection can be a problem. The connector terminals for both the VR and the ECU are--- wire--crimped to terminal--terminal to ECU pin. So right there in about 1/4 of an inch, you can have TWO bad connections.This part?
I can check voltage to pin 1 on the ECU when cranking. I'm a mechanical guy not electrical. Give me a break
Same thing at the ballast. The ballast has flag push on terminals. so the wire--crimped to wire end----wire end to ballast terminal. So again right there you can have two bad connections. Oxidized 60 year old wire and terminals, and oxidized ballast and wire end
One thing that can help, if the terminals are still tight is to simply work the connector in/ out off the terminal, to "scrub" them clean. If the spring in the terminal is still tight, that can often clean them
Bulkhead terminals are often quite different. The terminals and wire were undersized for larger alternators and heavy duty lamps and trailer towing. So those terminals are often heat damaged. Only fix is to cut the wire back and clean it, and install new terminals.
I found that the sheet metal nut that the hold down screw goes into on the ECU was jammed into the connector. Perhaps it was preventing it from seating properly. The engine started while cranking so that is a good sign. I'll get it out on the road and warmed up too see if that was the issue.
That is possible. I would pull it out, work it in/ out to scrub the terminals. Inspect it visually for corrosion, etc
Those types of connectors, the distributor pickup, the ECU, the VR, and flat trailer connectors can be cleaned if you can find a .17- .177 rifle bristle brush.
Those types of connectors, the distributor pickup, the ECU, the VR, and flat trailer connectors can be cleaned if you can find a .17- .177 rifle bristle brush.
It’s all new
I have a saying from long ago, and it turns out, some of the guys here have the same one. "New" does not mean functional.
I've got about 14 years at two parts stores in a previous life, and I've seen a few "new" things come out of the box, that were not functional
I've got about 14 years at two parts stores in a previous life, and I've seen a few "new" things come out of the box, that were not functional
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