🔍 Key Concepts

• Diesel fuel injector operation and spray pattern • Effects of overheating at the nozzle tip • Differences between leakage past the needle vs. blockage of nozzle holes

💭 Think About

• What engine condition would cause the very tip/lower end of the injector to run hotter than normal for a long period of time? • Which of these faults would most directly expose the nozzle tip to continuous combustion gases? • Which options would more likely affect pressure or flow inside the injector body rather than overheating the very end?

✅ Before You Answer

• Note that heat discoloration at the lower end means the nozzle tip has been excessively hot, not just the body of the injector • Consider which fault would allow hot combustion gases to blow back around the nozzle tip • Eliminate options that mainly involve internal fuel return or lift without directly overheating the nozzle tip