An injector includes an injector body having an upper portion defining a top surface. An injector core is received through the upper portion. The injector core has an interfacing surface that is disposed adjacent and raised with respect to the top surface. A cover member is disposed on the upper portion of the injector body. The cover member has a top wall for receiving at least a portion of the injector core, a side wall extending from at least a portion of the top wall, and a lip that is adapted to be attached to the other of the side wall or the injector body through a snap-fit connection. Upon attachment of the lip to the other of the side wall or the injector body, the top wall of the cover member presses on the interfacing surface of the injector core to restrict an axial movement of the injector core relative to the injector body along the longitudinal axis.