Abstract: A pressure regulator is provided for the fuel injection system of a spark ignition internal combustion engine. The regulator is designed to regulate the pressure at which fuel is delivered to the fuel injectors, this pressure being constantly referenced to a predetermined value for the purpose of maintaining the correct air/fuel mixture ratio for all conditions of use of the engine. In general terms, the regulator comprises an arrangement of various mechanical components which act to divide the flow of fuel delivered by a supply pump into two parts; one part of this flow is supplied to the injectors which take up the quantity required by the operating conditions of the engine, the remaining part being returned to the motor vehicle tank. To facilitate manufacture and assembly of the regulator, a particular form is given to the regulator valve element used to effect division of the fuel flow.