🔍 Key Concepts

• diesel engines rely on heat of compression, not a spark, to ignite fuel • what happens to fuel delivery if there is air or contamination in the fuel system • difference between problems that affect starting air vs. those that affect fuel injection

💭 Think About

• Ask yourself: if the engine is cranking at normal speed, what does that tell you about the starting air system? • Which option would most directly prevent the correct amount of fuel from reaching the cylinder at the right pressure and timing? • Which conditions listed would still allow combustion to occur once the engine is already turning normally?

✅ Before You Answer

• Verify which options affect fuel pressure and continuity to the injectors. • Check whether an issue with starting air would still allow the engine to crank normally. • Consider which conditions are more likely to cause no ignition at all, rather than just harder starting or more wear.