🔍 Key Concepts

• Fuel injection pump plunger design and how fuel quantity is controlled • The function of the spiral/angled cut on the plunger surface • Difference between a sleeve or barrel and the shaped features on the plunger itself

💭 Think About

• Look closely at what the label M arrow is actually pointing to: is it pointing to a separate part around the plunger, or a shaped surface on the plunger body itself? • Ask yourself which plunger feature is responsible for starting or stopping fuel delivery as the plunger is rotated by the control rack. • Compare the terms in the choices: which names sound like a whole surrounding piece, and which sound like a specific machined feature on the plunger?

✅ Before You Answer

• Verify that M follows a spiral or helical path rather than being a flat shoulder or tab. • Confirm whether M is part of the plunger body or an outer sleeve/barrel around it. • Match the visual shape of M with the common textbook diagram of a plunger’s fuel‑control helical cut.