a fuel inlet opening 56 at the exposed upper end a ring 58 that is disposed around the outside of fuel inlet tube 12 just below fuel inlet opening 56 cooperates with an end surface 60 of cover 36 and the intervening o d of tube 12 to form a groove for an o ring seal 61 that is typically used to seal the fuel injector inlet to a cup or socket in an associated fuel rail not shown the lower o ring 44 is for providing a fluid tight seal with a port in an engine induction intake system not shown when the fuel injector is installed on an engine filter assembly 16 is fitted to the open upper end of adjustment tube 14 to filter any particulate material larger than a certain size from fuel entering through inlet opening 56 before the fuel enters adjustment tube 14 in the calibrated fuel injector adjustment tube 14 has been positioned axially to an axial location within fuel inlet tube 12 that compresses spring 20 to a desired bias force that urges the armature needle valve such that the rounded tip end of needle valve 24 is seated on valve seat member 40 to close the central hole through the valve member seat preferably tubes 14 and 12 are crimped together to maintain their relative axial positioning after adjustment calibration has been performed after passing through adjustment tube 14 fuel enters a space 62 that is cooperatively defined by confronting ends of inlet tube 12 and armature 22 and that contains spring 20 armature 22 comprises a passageway 64 that communicates space 62 with a passageway 65 in valve body 30.