🔍 Key Concepts

• Precision fit between diesel fuel pump plunger and barrel • How wear affects fuel leakage and injection pressure • Why fuel pumps are usually serviced as matched components

💭 Think About

• Which parts of a fuel injection pump are manufactured and fitted together as a matched set? • If the plunger is worn, what happens to clearances and sealing between plunger and barrel? • Would reworking only one surface maintain the original precise fit and injection characteristics?

✅ Before You Answer

• Consider whether clearance between plunger and barrel can be restored by working on only one piece • Think about leakage and pressure loss if the fit is no longer perfect • Recall standard manufacturer practice for replacing precision-matched fuel pump parts