Fuel Injection System - 4-CYL Diesel: Operation: Injectors
The injection nozzles inject fuel directly into the pre-combustion (swirl) chamber. Injectors are connected in series with a fuel return line. When fuel from the injection pump reaches 2000 psi (141 kg/cm2 ), needle spring pressure is overcome.
The needle valve is lifted off its seat and allows fuel to enter the cylinder. During this process fuel lubricates the nozzle between the needle valve and nozzle body.