Help with Electrical Gremlin

Looking for some help tracking down an electrical gremlin that popped up this weekend.



Backstory

The 66 Barracuda hasn’t been driven a lot for reasons unrelated to the car. Other than that, the car was in great running order. Normal stating process: remove from trickle charger, partially turn the key for the electric fuel pump (in tank pump from Tanks Inc. installed in January 2021) to turn on, pump the gas pedal, and start the car. Over the past couple of months, when I went to start the car, the electric fuel pump would turn on and then just click when the key was turned to start. This would also take out electrical to the car. I would remove the negative from the battery which would restore electrical to the car and start the process over. It usually started on the second or third try. After research, it appeared to be related to a relay. There are two relays, a 50 amp for the fuel pump and a 40 amp for the fan. I would tap relays and the car would start. After the car started running there were not any further starting issues even after restarting later that day or even the next day. It appeared only after sitting. Sadly, I was busy doing other things to chase down this problem.



This weekend.

My daily car is in the shop, and I had to drive the Barracuda. She drove perfectly fine on Saturday. Early Sunday morning I experienced all the starting issues listed above before getting the car to start. My son and I then drove 35 mountainous miles with zero problems. The car drove great. On the return trip, she started up fine and ran great for about 2/3s of the way home when we hit some traffic.

The symptoms

The car started surging, on the AFR gauge it was leaning out. At times it appeared to die with the tachometer not showing any RPM. It would then come back. As mentioned, it is a mountainous drive and the area would have been super shitty to pull over. Thankfully, it was all downhill and I kept going. I made it a block from my house and the car died at a stop sign that I was rolling through. After 10 minutes I was able to get it started and mostly into the garage before dying. Of note, the electric fan was on and working and I believe that relay was clicking before the car died. The relays are 5 to 6 inches apart in the same area of the engine bay.



Trouble Shooting.

Assuming it was relay related. I’ve replaced both relays and have gone through the immediate wires from the relay to the circuit breaker to the battery. I’ve also tested removing the electric fan and starting the car. Initially, the car would not start. After a couple of attempts, I started the car without the fuel pump. It fired right up off the gas in the carb.

Reconnecting the fuel pump, I was able to get the car started but had surging before it cut off. Also of note, the fuel pressure is around 6.5 psi.



Next steps

I plan to trace all the fuel pump wires to find any faults. Other than that, I am at a loss



Any advice that I should look at? Would a circuit breaker go bad and cause this problem?

Thank you for the help