Diesel engines rely on different types of fuel injection. Mechanical was used early on, but common rail became more popular for a few reasons.

Ford Motor has patented a method for adjusting injection timing of closely spaced multiple injections using the same injector. The system adjusts timing based on previous injections, optimizing fuel ...

Mechanical injection systems rely entirely on engine driven components to meter, pressurize, and time fuel delivery. In these engines, a mechanical injection pump is driven by the engine's gear train ...