9. What is located above the plunger ?
• Vertical channel or slot
• Helical channel grove
• Annular grove
10. Types of non-return valve :
• Suction non-return valve
• Delivery non-return valve
11. How does a leak in the non-return valve affect fuel pump delivery ?
• A large leak will cause a drop in pressure, and the injector will not spray properly.
• A small leak will not affect the pump pressure; however less fuel will be sprayed
through the injector.
• A small leak will slow the pump, and the fuel spray will be delayed.
12. Fuel pump pressure : Fuel pump delivers 240-700 Kg/cm2 (4000-10,000 Psi)
13. Wearable and breakable parts of a fuel pump :
• Wear of plunger
• Wear of plunger bush
• Plunger retaining spring can lose tension
• Plunger-retaining spring can break
• Wear of bush and ball bearing
• Wear above tappet and bottom of plunger
• Wear of roller and fan