🔍 Key Concepts

• fuel injection systems and how they work in diesel engines • difference between mechanical settings (timing/positions) and physical properties of the fuel • what happens between the start of pump delivery and the actual injection at the nozzle

💭 Think About

• Think about which option describes something that would slow down or delay the actual start of injection after the pump begins to deliver fuel. • Ask yourself: which factor would exist even if all the mechanical parts are adjusted perfectly? • Consider what could create a small time delay inside a high‑pressure fuel line before the injector opens.

✅ Before You Answer

• Identify which choices involve mechanical adjustment versus a built‑in property of the fuel system. • Consider how pressure must build in the fuel line before the injector needle lifts off its seat. • Verify which factor would still be present even if the timing, plunger setting, and needle position were all correctly adjusted.