Yes Joe, a fuel pressure regulator.

Reference pressure is taken from a sensor tube near the air inlet of the carburetor to create a setpoint for the fuel pressure regulator at the same value as the air inlet pressure of the carburetor.

It's a method to eliminate the influence of the hydrostatic pressure differences and G-load caused by attitude of the plane and location of the tank. Only difference now is the distance between the centre of the regulator and the spraybar of the carburetor.

Picture made from another position does show the reference tube.
Temperature measurement of the glowplug base is done with a thermocouple and the cold junction is mounted on the regulator. This has advantages for the cold junction temperature compensation.



Cees