🔍 Key Concepts

• Common rail fuel injection basics: how pressure and timing are managed • Difference between mechanical control (cams, racks) and electronic control • What actually meters fuel quantity to each injector in a modern common rail system

💭 Think About

• Ask yourself: In a common rail system, is fuel pressure created and stored separately from the device that decides how much fuel goes into each cylinder? • Which of these choices would be responsible for metering and timing the injection, rather than just turning or driving the engine’s mechanical parts? • Think about older mechanical fuel systems versus modern electronically controlled ones—what changed in terms of controlling fuel quantity?

✅ Before You Answer

• Identify which options are purely mechanical drive components and which involve control and decision-making. • Recall that in common rail systems the rail maintains high constant pressure, and the fuel amount is controlled at the injector, not by varying pump stroke the old way. • Verify which device can adjust injection quantity and timing based on inputs like load, speed, and temperature.