🔍 Key Concepts

• Follow the direction of fuel flow from the service tank through filters, pump, injectors, and back to the tank. • Know the visual difference between high‑pressure injector lines and low‑pressure supply/return lines on a diesel fuel system. • Understand what the injector leak‑off (return) line does and where it must lead.

💭 Think About

• Look at where item "11" starts and ends: does it go from the injection pump to the injectors, or from filters to the pump? What type of line normally connects those components? • Trace the small line that item "13" labels across the tops of the injectors. What function do these small connections on the injector bodies usually serve? • See where item "15" goes when it leaves the injection pump. Does it feed fuel into the pump, or does it carry excess fuel away from the pump back toward a tank or separator?

✅ Before You Answer

• Verify whether item "11" runs from the injection pump outlets directly to each injector (typical of high‑pressure lines) or from a filter/transfer pump (low‑pressure). • Confirm that item "13" connects the leak‑off fittings on top of all injectors and then leads back toward a return point rather than a supply point. • Check if item "15" is connected to a point on the injection pump where excess fuel/air is bled off and then routed back to the day tank or separator, which would indicate a return line.