I am having the same issue with my '76 280z... even having those two wires coming out of the ECU harness. I am going to research it, work on it, and report back. Thanks for all the info already.

~N

Just a follow up, i've managed to go through 3 tank refills and nearly two weeks with out a starting stall after replacing the fuel filter. I'll continue to monitor and post results. If anything, my next step will be to clean the gas tank.

I had the same problem years ago on my 76 and if your car is solid enough don't part it just go with a weber set up I still have them on the car and it runs great

I am experiencing somewhat similar problems.

starts up fine but occasionally it bogs and stalls out and dies shortly thereafter.

in relation to that the clutch is bad since its not responsive however I also started to notice a fuel smell from outside the car. which leads me to believe its fuel related. Im guessing fuel filter as well!

I'll have it replaced soon and report back how it worked!

Another follow up: got a stall / hesitation with new fuel filter. Changed fuels for the past few months (87 to 91 octane) and haven't seen any issues. Still haven't peeked in the fuel tank nor looked at fuel pump, but at least things are promising. At this point if I do get something again I'll drop the tank.

FYI, on my 76 wiring there are 2 unused wires coming to the ECU. If I remember correctly, both are white. Both have female connectors attached. I also had purchased another wiring harness from a 76 which had the same 2 wires. Maybe Datsun engineers intended to use them for something else, and later changed their mind?

Those two white wires come up in discussion periodically. They serve no purpose for the car user, apparently they might be for for diagnostics. They don't do anything and they're always disconnected.