Abstract: A three-part valve means is used in an electromagnetic fuel injector to control fuel flow out through a metering orifice, defined by the valve means in an open position relative to an associated valve seat, to an injector discharge orifice located closely downstream of the metering orifice. The three-part valve means includes a valve member provided with a flat surface on one end thereof and a semi-spherical seating surface at its opposite end for seating engagement with the valve seat; a movable armature having a flat at one end thereof for abutment against the flat surface of the valve member; and, a valve retainer operatively connected to the armature for supporting the valve member with its flat surface in abutment against the flat of the armature for movement therewith, the valve retainer permitting the flat surface of the valve member to move transversely relative to the flat of the armature.

Abstract: An electromagnetic fuel injector has a guide pin for axial alignment of a movable armature. The guide pin is provided with an abutment shoulder thereon for engagement with a surface of the armature whereby to serve as an abutment so as to establish a predetermined minimum working air gap between the opposed surfaces of the armature and the pole piece of the associated solenoid coil.

Abstract: In an electromagnetic fuel injector at least one and preferably the physically softer one of the opposed working air gap surface of the pole piece and armature of the injector solenoid assembly has a roughened surface texture thereon with an average surface roughness rating value of the order of 16 to 32 microinches.