A modern Cummins fuel injector is a complex assembly, not just a single part. Understanding its key components helps in diagnosing issues. The main parts include:
Nozzle and Tip: This is the business end of the injector. It has extremely fine holes that atomize the fuel into a fine mist for optimal combustion. Wear here leads to poor spray patterns, dripping, and increased smoke.
Plunger and Barrel: This is a high-precision pump assembly. The plunger moves up and down inside the barrel to create the immense pressure needed for injection. Wear between these two components results in low injection pressure and power loss.
Solenoid/Actuator: This is the electronic trigger. It receives a signal from the Engine Control Module (ECM) to open and close the injector at the exact millisecond required.
Check Valve/Spring: This component ensures a sharp end to the injection event, preventing fuel dribble after the solenoid closes.
Filter Basket: A small internal filter that catches any large contaminants in the fuel before they can damage the sensitive internal parts.