Which fuel injection system uses a common rail with electronic control?

• A. Common Rail Type Electronic Control
• B. Unit Injector
• C. Direct Injection
• D. Mechanical Pump

Answer: (A)

A common-rail, electronically controlled fuel system uses a single high-pressure rail that feeds all injectors, with the engine computer regulating rail pressure and injector timing through electronic signals. This shared rail design lets the ECU precisely control when and how much fuel each injector delivers, enabling multiple injections per cycle and optimal performance or emissions.

Unit injector systems don’t use a central rail; each cylinder has its own pump and injector, so there’s no common rail to feed all injectors. Direct injection describes injecting fuel directly into the combustion chamber, but it can be implemented with different rail concepts; the key distinction here is the presence of a single high‑pressure rail shared by all injectors. Mechanical pump systems rely on purely mechanical timing and lack electronic control at the injection point.

So the description that matches a common high-pressure rail with electronic control is the correct one.