Which of the following is NOT a type of fuel injection system?

• A. Unit injector (designed with simplicity in mind)
• B. Electronic Unit Injectors
• C. Common Rail Type Electronic Control
• D. Direct fuel injection pump system

Answer: (D)

Fuel delivery arrangements are classified by how fuel is metered and delivered to the cylinders. Three modern, recognized configurations are unit injectors (one injector per cylinder that includes its own pump), electronic unit injectors (each injector is electronically actuated for precise timing and quantity), and common-rail systems (a high-pressure rail feeds all injectors with electronic control). The description of a direct fuel injection pump system isn’t treated as a separate injection system type in these classifications. It refers to the pump architecture that supplies injectors, rather than a distinct method of injecting fuel into the cylinders. The other three are established, distinct injection system types, while a “direct fuel injection pump system” is not categorized that way.