🔍 Key Concepts

• minimum firing speed required for compression ignition in a diesel engine • relationship between cranking speed, compression temperature, and fuel ignition • what each option (fuel rack issues vs. mechanical engagement) actually affects in the starting process

💭 Think About

• When a diesel engine is cranking slowly, what happens to the air temperature at the end of compression? Is that enough for auto‑ignition of fuel? • Which of the choices describes a condition that would prevent the engine from reaching the speed needed to ignite fuel, versus conditions that happen after normal cranking speed is achieved? • Look at each option: which one directly addresses why the engine would crank but never begin to fire at all?

✅ Before You Answer

• Identify the role of cranking speed in achieving compression temperature for ignition in a diesel • Decide which options talk about fuel quantity/adjustment versus rotational speed/engagement • Confirm that your choice explains why the engine is turning over, but no combustion is starting