Fuel Sender

The fuel level 'sender' is the sensor in the tank.

Sedan sender

Specifications

As measured by club members, by moving the float up and down from stop to stop:

12 ohms fully up
88 ohms fully down
35 ohms half full (per Nissan Factory Service Manual)

NOTE: This does not necessarily match "Full" and "Empty" marks of the fuel gauge, due to normal manufacturing tolerances. Typically a 1200 reads well 'E' before it runs out of fuel, this is normal.

Reference: Forum: Fuel sending unit specs

Also see:

Fuel Gauge (includes Fuel gauge specs)
Wiring - Troubleshooting Fuel Gauge

Return Line

Starting in 1975, North American B210s were fitted with a fuel return line. Here's what the Nissan publication "Introduction of Datsun B210 (1975 model)" says:

Fuel return system
For preventing abnormal fuel temperature rise, the fuel return system has been installed. In this system, fuel from the fuel tank is delivered to both the carburetor and fuel tank.
The fuel return line services to return a part of the fuel to the fuel tank to suit different engine operating requirements, preventing the possibility of fuel heated flowing through the fuel line inside the engine compartment, and elminating "percolation" inside the carburetor.

Parts Sources

Nissan. Call Ericksen Nissan's toll-free number. If Ericksen says they can't get a part let us know (click "Edit" and add it to this article). Also, if they do get the part for you, let us know that too!
- NOTE: Nissan USA is out of stock forever of the Sedan hose. But perhaps they can get the Coupe hose.
Wreckers, if you can find a 1200 in a wrecking yard
Friends with parts cars
Marine supply stores, for general fuel hose and filler hose. NAPA and other old-line auto parts store carry this generic fuel-rated hose also. Trimmed to length using the old filler hose as a guide. It is tough getting it to flex into shape, but can be done.

Filler Hose

Coupe

USA B110 coupe tank

Sedan

Note that the USA B110 sedan tank uses a 2-piece filler hose (there's a small hose inside the bigger one). This is for the EVAPO (emissions market) vehicles:

Two-piece curved filler hose for EVAPO system