Fuel Distributor: Description and Operation

Fig. 2 Fuel Distributor with Frequency Valve:

The fuel distributor, Fig. 2, distributes the fuel to the individual injectors and consists of a fuel control unit and four pressure regulating valves, one for each cylinder.
The skirt of the control plunger is in constant communication with the line pressure, which also acts on the bottom of the pressure regulating valve. When the control plunger is raised by the lever from the air flow sensor plate, four metering slots, which feed the fuel to the top of the pressure regulating valve, will be opened. The pressure above the spring loaded diaphragm acts upon the diaphragm, forcing it downwards and opening the outlet to the injectors. A pressure differential of 1.5 psi (0.1 bar) is maintained between the line pressure and the control pressure acting on the top of the diaphragm. This constant pressure differential is necessary to ensure that the injected quantity of fuel always remains proportional to the open area of the metering slots, measuring the fuel quantity equally to all four injectors.

Fig. 14 Fuel Distributor (Partial View):

Fuel under control pressure is removed from the system via an orifice, Fig. 14, in the in the fuel system. The control pressure is lowered to 54 psi (3.7 bar) and 7 - 54 psi (0.5 - 3.7 bar) during the warm up period due to the pressure drop across the orifice. The amount of pressure dropped across the orifice is determined by the amount of fuel flowing through the orifice and the warm up regulator. An additional orifice is located between the control pressure passage and the top of the control plunger, and is designed to eliminate rapid oscillation of the air flow sensor level.

The fuel distributor also contains fuel inlets and outlets, a fuel pressure regulator, and passages for the fuel control pressure.