fuel regulator

I personally don't think it would matter since there's people here who run without it connected, but my car had the wire soldered onto the sensor. You are talking about the Fuel temperature sensor, right? http://www.twinturbo.info/mediac/400…emp~sensor.jpg

Yes! You are correct.

For the 1984 model year, as the fuel in the fuel rail gets warmer the Fuel Temperature Sensor relays the temperature increase to the ECU in order to enrich the currently referenced fuel cell to add more fuel. This is referenced on page EF & EC-20 of the 1984 FSM. This is not referenced for 1985 and later models in the FSM so this system may have been removed or revamped maybe due to issues with the early models being the prototype. However, if you've got a 1984 model, you might run lean as the temperature inside the fuel rail increases with the fuel temperature sensor disconnected.

It's an 86 N/A.

FSM says "Startability" in the Diagnostic Procedure. I replaced one on my 85 n/a a long time ago, can't remember why. I don't think you could buy the sensor by itself, you had to get the Fuel Pressure Reg assembly, at least from Nissan. I just grabbed one off another Z and life was good again. If you decide to replace the assembly, make sure it comes with the sensor, I don't think the Ebay ones do, but I think the ones from nissan do.

I think the fuel temp sensor affects startability at certain temperatures. It has a one wire connection and mine isn't bolted to the LIM at the moment so there's no ground and it doesn't work. I've noticed that when it's like 10-15 C (50-60 F) outside, it sometimes struggles a bit when starting. I think it was better when I still had the sensor connected.

According to Nistune, if the fuel temp sensor is unplugged or not working, the ECU sees the fuel temp as a constant -50C (which is a sensible safe fail condition, I guess.)