🔍 Key Concepts

• jerk-type fuel pump basic operation in a diesel engine • how fuel quantity and cutoff are controlled inside the pump barrel • the role of a plunger’s shape or motion versus valves and ports

💭 Think About

• In a jerk-type pump, what physical change inside the pump actually stops fuel delivery at the injector—movement of a valve, opening of a port, or rotation/position of the plunger? • Which component is specifically designed to vary the effective stroke that delivers fuel, rather than just allow leakage or cushioning? • Look at the choices: which one is used to time and meter the end of injection by uncovering or changing a passage, not just to seal or spring‑return something?

✅ Before You Answer

• Identify which part directly determines when pressure drops below injection pressure, ending delivery. • Decide which options mainly act as one‑way valves or springs (supporting parts), not metering/control parts. • Confirm which component in most jerk-type pumps has a special surface or feature that, when rotated, changes the delivery cutoff point.