Fuel injection system

A fuel injection system for a mixture-compressing spark ignition internal combustion engine with continuous injection including an air inlet passage containing an adjustable throttle valve, said fuel injection system comprising:

• a flow sensing device for measuring the rate of fuel flow;
• a fuel metering valve, actuated by the flow sensing device, in which fuel metering occurs at a controlled constant pressure difference;
• and
• a differential pressure regulating valve which adjusts the fuel metering valve, said differential pressure regulating valve having a first chamber and a second chamber separated from the first chamber by a diaphragm, the first chamber being in communication with a return pipe via a valve element which can be moved in a bore by the diaphragm, and the second chamber being subject to pressure upstream of the metering valve, said differential pressure regulating valve also having a first spring means acting upon the side of the diaphragm facing the first chamber, and a second spring means acting upon the side of the diaphragm facing the second chamber, said first means comprising a strong spring acting directly on the diaphragm and a contact spring which keeps a movable valve element in contact with the diaphragm wherein the constant pressure difference supplied by the differential regulatory valve to the fuel metering valve is varied in accordance with the operating conditions of the engine by varying the force of the contact spring.