🔍 Key Concepts

• Jerk-type fuel injection pump operation shown in MO-0097 • Function of the plunger helix and spill port in controlling start and end of injection • Difference between a delivery check valve and a spill valve/port in a fuel injection system

💭 Think About

• Trace the path of fuel from the cam-driven plunger up to the injector and ask: what specific event causes pressure at the injector to suddenly collapse? • Look at component "H" in the illustration: how does rotating or moving this part change when the high‑pressure fuel stops flowing to the cylinder? • For each choice, decide whether that event would end high pressure delivery to the injector, or merely control plunger motion or prevent backflow.

✅ Before You Answer

• Identify which part in the drawing is the plunger with the control helix and where the spill port is located relative to it. • Confirm which component actually relieves high pressure in the pump chamber back to a low‑pressure area. • Verify that the delivery check valve function is to prevent reverse flow, not to actively terminate injection in this type of pump.