In-line fuel injection pumps have one pump element for each engine cylinder. These are arranged in a row. The camshaft of the in-line fuel-injection pump is driven by the gear wheels or chains of the combustion engine. The in-line fuel-injection pump runs at half the speed of the engine and always synchronously to the piston movements of the diesel engine. The fuel reaches the nozzle-holder assemblies with the injection nozzles via high-pressure lines.
The in-line fuel injection pump is the "classic" among injection systems. Nowadays it is only to be found in commercial vehicles, buses, building-site and agricultural machines or in stationary diesel engines. It permits injection pressures of up to 1,300 bar.