This is something I posted in another thread recently -
"Have you checked to see whether or not your getting fuel to the rail? I believe the easiest way is by pulling the hose from the cold start injector, placing it in something that can catch any potential/hopeful fuel and turning the key to the 1st on position (not the start position). You should hear the fuel pump try to prime/pressurize the system for a very short time and if the pump's working, you'll get some fuel out of this hose. If not, but you did hear the fuel pump, there's a check valve (basically a ball with a spring behind it) in the outlet from the pump. Sometimes, this can get stuck in the closed position and will keep fuel from exiting the pump. Eric at HiPerformance told me about this a few years ago when mine was stuck and I couldn't figure out was was going on. A mild push and all was good to go.
If your fuel pump seems to be not working (not turning at all, though you've definitely got voltage going to it), you can get access to it's guts by removing the piece with the check valve. I did once get a non-working fuel pump up and running by spraying a fair amount of PB Blaster into this opening and letting it soak overnight. Then, with gentle use of a screwdriver, I was able to get the inner part that spins to free up."
My car is also a '72 164E. The above occurred after that car sat for a few months while I had pulled the head so that I could clean out the block. I also recently had a non-start problem after driving without any issues from San Leandro to Palo Alto. After playing pickleball for a few hours, the car wouldn't start. Ended up being the ball in the check valve again, though this was a NOS check valve, not the one I had the original problem with, so definitely a possibility, especially if you're not getting fuel up to the injectors.
