General

Bosch VE fuel-injection systems have a vane-type fuel-supply pump that draws fuel from the fuel tank and delivers it to the injection-pump cavity. The supply pump delivers a virtually constant flow of fuel. To obtain a defined pressure level proportional to engine speed, a pressure-control valve is required. With this valve, pressure can be set to correspond to a particular engine speed. This means that the pump-cavity pressure increases along with rising engine speed.
A portion of the fuel flows through the pressure-control valve and returns to the suction side. For cooling and self-ventilation of the distributor injection pump, some fuel also flows through the overflow restriction on the governor cover and back to the fuel tank.