🔍 Key Concepts

• Relationship between exhaust smoke color and fuel/air mixture in a diesel engine • What engine "overload" does to combustion and fuel burn • Difference between complete combustion and incomplete combustion

💭 Think About

• Think about what happens if too much fuel is injected for the amount of air available—what color would the exhaust likely be? • Which choice describes a condition that would make the engine work harder than it should for the power demanded? • Which option clearly does NOT match the idea of unburned or partially burned fuel in the exhaust?

✅ Before You Answer

• Match black smoke with unburned/partially burned fuel in the exhaust. • Eliminate any choice that suggests perfect or complete combustion. • Ask which option most directly relates to excess fuel for available air (rich mixture) or engine overload.