Modular fuel injector having interchangeable armature assemblies and having a lift set sleeve

A fuel injector (100) for use with an internal combustion engine. The fuel injector (100) comprises a valve group subassembly and a coil group subassembly. The valve group subassembly (200) includes a tube assembly having a longitudinal axis that extends between a first end (238) and a second end (239); a seat (250) that is secured at the second (239) end of the tube assembly and that defines an opening; an armature assembly (260) that is disposed within the tube assembly; a spring (270) that biases the armature assembly toward the seat (250); an adjusting tube that is disposed in the tube assembly and that engages the spring (270) for adjusting a biasing force of the member; a filter (284A) that is disposed at least within the tube assembly. The coil group subassembly (300) includes a solenoid coil (312) that is operable to displace the armature assembly (260) with respect to the seat (250). The armature assembly (260) includes a sealing portion (264), a magnetic portion (262) and optionally an armature tube (266) in between. Furthermore, the valve group subassembly (200) includes a lift sleeve (255) to set a relative axial position between the seat (250) and the tube assembly.