A plunger is used in the fuel injection pump...

A plunger is used in the fuel injection pump...

Question 1 of 270705eccefa2bacbc34ba4d47869

A plunger is used in the fuel injection pump shown in the illustration 'timed for port closing.' The injection process will always have a __________. See illustration MO-0063.

Question 1 of 27070

Q

A plunger is used in the fuel injection pump shown in the illustration 'timed for port closing.' The injection process will always have a __________. See illustration MO-0063.

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This question does not have an illustration

🔍 Key Concepts

• Port-closed fuel injection timing and what event actually starts injection in this type of pump • How the plunger helix and spill port affect when injection stops • Difference between controlling start of injection vs. controlling end of injection to change fuel quantity

💭 Think About

• Look at the illustration and identify exactly what happens at the moment the spill ports are closed by the plunger. Does this event depend on rack position, or is it fixed by the cam? • Then, think about what changes when the control rack moves the plunger helix. Does this movement shift the start of injection, the end of injection, or both? • Ask yourself: to vary fuel quantity from minimum to maximum, which is easier mechanically in this design—changing when injection begins or when it ends?

✅ Before You Answer

• Verify which part of the plunger is aligned with the spill ports at the start of effective stroke and whether that point moves with rack adjustment • Confirm how rotation of the plunger (by the control rack) alters the helix-to-port relationship during the upward stroke • Decide whether the design produces a fixed start of injection with variable cutoff, or a variable start with fixed cutoff