HELP! 71 911T wont start.

[Jeremy911T]

I have a 71 911T with Zenith Carbs and a Marelli distributor. It underwent a complete restoration in the late 90’s and recently came out of a 3.5-year hibernation. After some initial work rebuilding the carbs and getting the some brake work done, it ran great for a few days. Then the CDI unit went bad, had it rebuilt, and again ran great until 2 days ago. After a 10 mile trip I went to restart it after lunch and it wouldn’t fire up. The engine would turn over fine. Waited 20 minutes same thing. Had it towed home and pulled off the fuel line and the pump was pushing plenty of fuel. I don’t have a fuel pressure gauge, but the carbs I think only need 3 PSI. Checked for spark and nothing. I thought it might be the CDI unit again and it wasn’t singing so I took it to the gentleman that rebuilt it along with my coil and he put them through the paces including heating up CDI unit and it was working fine on his bench although the typical “sing” of the unit was very faint. He suggested I check a few things which I did. There was 12 volts coming from the center (B) pin of the 3 pin CDI unit, there was continuity between the CDI “C” pin and the distributor, and there was continuity between the “A” pin and the coil. I also pulled off the distributor cap and rotor. They appeared ok. The points would open and close as I manually rocked the advance on the distributor. Of note and it may not be related, the morning after I had it towed home, I went to attempt to start the car and it would barely turn over like it had a weak battery. I cleaned every terminal and connection I could find in the engine compartment and all the connections to the two batteries in the bonnet and the transmission ground strap under the car. I found a surprising amount of corrosion on the brass connections from the batteries to the starter cable. After I spent a few hours doing this the car would again turn over like a normal Bosch starter. The gentleman that rebuilt my CDI unit said I could borrow another unit to see if that made a difference which I might take him up on. What am I missing here?! Is there a fuse I am missing? Any help would be very appreciated. Thanks, Jeremy.

[timmy2]

Based on your lengthy detailed write up.
1. Clean the points and check the dwell.
2. Swap out the CDI as offered.

[Trackrash]

Another check to do is measure the voltage at the CDI when you are cranking. If it drops too low you may not have any spark.

[doswald]

Make sure the small wire that supplies power to the points hasn’t fallen off or become corroded.

Dho

[WMontald]

Change Coil and bypass the CDI
As within example with 123 Ignition, but with your Marelli
You can use the Bosch Red Coil or Beru ZS 565