F 250 4WD Super Duty V8-6.4L DSL Turbo (2008)
Main Injection Step 1
Fuel under pressure from the rail (7) reaches the control piston chamber (2) and the high pressure chamber (3) of the nozzle needle (5).
^ The bore hole to the fuel return line is closed via the valve mushroom (4) which is held closed by a spring and high pressure fuel.
^ The surface area of the control piston is much larger than the surface area of the nozzle needle in the high pressure chamber.
^ The force (F1) exerted by the control piston due to its larger surface area along with the force of the needle control spring overcomes the force (F2)
exerted by the smaller surface area of the nozzle needle in the high pressure chamber which holds the nozzle needle closed.
