🔍 Key Concepts

• Jerk-type fuel injection pump components and how they meter fuel • How the plunger helix and spill port control end of injection • Difference between pressure generation and quantity control in fuel pumps

💭 Think About

• Which part of the jerk pump actually "decides" when to stop delivering fuel on each stroke? • Does changing cam shape or supply pressure change the timing of fuel cutoff, or the metered quantity for each stroke? • In this type of pump, what rotates or shifts to change the plunger’s effective stroke that delivers fuel to the nozzle?

✅ Before You Answer

• Identify which component directly controls start and end of injection in a jerk pump • Verify how the plunger helix orientation affects when fuel is spilled back to the low‑pressure side • Confirm whether rack movement acts directly on fuel quantity or acts through another part (like a sleeve or plunger) to change effective stroke