Fuel Distribution System

The fuel distribution system includes an electric supply pump, separate injectors for each cylinder, and mixture control unit mounted system pressure regulator and equalization regulators for each injector. The pump supplies sufficient fuel for full throttle operation at all times, with excess fuel returned to the tank through the system pressure regulator. A relief piston within the regulator maintains system fuel pressure at a constant value, and the regulator also supplies pressurized fuel for the control pressure regulator and frequency valve.

The fuel injectors open at a calibrated pressure and spray fuel continuously as long as applied pressure is above this calibrated value. The amount of fuel supplied to the injectors is determined by control plunger position, but actual injector pressure is controlled and equalized by separate regulating valves for each cylinder. Each equalization regulator consists of two chambers separated by a steel diaphragm, with a spring loaded disc valve linking the chambers. Pressure is applied to the lower diaphragm chamber from the lower control plunger chamber, and pressure is applied to the upper diaphragm chamber through the control plunger metering slot. When the control plunger opens the metering slots, pressure applied to the upper chamber forces the diaphragm down, the disc valve opens, and pressurized fuel is supplied to the injector. Approximately 11/2 psi of fuel pressure is ``used up'' opening the disc valve, creating a pressure differential between the inlet and outlet sides of the fuel metering slot. This pressure differential allows the control plunger to regulate the amount of fuel supplied to the injectors without being affected by pressure fluctuations. When the engine is stopped and the control plunger closes off the metering slot, the disc valve in each regulator and spring loaded valves in each injector close, and fuel is trapped in the injectors and lines to aid starting. Calibration of the regulating valves is determined during manufacture and if the valves malfunction, the fuel distributor assembly must be replaced.