Clean the body and its oil passage, assemble the pressure regulating spring and pressure regulating screw together. Pay attention to the pressure regulating screw should not be screwed too tightly, so that in the later performance check for easy exhaust and overall cleaning. Place usable or new injector assemblies in a container with clean diesel oil and pump the needle valve back and forth for a thorough cleaning. Fix the pressure regulating part of the injector (should be below) on the bench vice, fasten the needle valve couple on the joint surface according to the positioning requirements, then tighten the screw sleeve of the nozzle, and then conduct the performance inspection.