Fuel Injection System - 2.3L Diesel: Operation: Injectors
The fuel injector nozzles inject fuel directly into the swirl combustion chamber. When high pressure fuel reaches 1707 psi (120 kg/cm2 ) or more, it overcomes the injector needle pressure spring, lifts the needle valve off its seat and sprays into the combustion chamber.
When fuel pressure drops below injector nozzle opening pressure, the needle valve closes, preventing fuel from entering the combustion chamber. The fuel lubricates the injector nozzle between the needle valve and seat, then returns to the fuel tank through the return line.