Ford 6.4L Power Stroke, Manual

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49
100
Fuel ManageMent SySteM
101
End of Main Injection Step 1
• The high pressure fuel, that is allowed to escape
past the valve mushroom (4) into the fuel return
line (6), is routed down a drilled passage to the
drain holes in the sides of the injector just below
the O-ring seal towards the base of the injector.
• The fuel is then routed through the cylinder head and exits
through a banjo fitting on the front side of the cylinder
head before being returned to the fuel supply system.
End of Main Injection Step 2
• When the Engine Control Module (ECM) determines that
the correct injector on time has been reached, it switches
the polarity of the piezo actuator (1) which causes
the piezo discs to return to a non-enerrgized state.
• Switching the polarity of the piezo actuator (1) enables
the valve mushroom (4) to seat via spring pressure
and completely block the bored passage that connects
the high pressure fuel to the fuel return line.
• Seating the valve mushroom (4) allows the pressure
to build in the control piston chamber (2) and
equal that in the high pressure chamber (3).
• Once these two chambers have equalized in pressure
the downward force (F1) of the control valve will
overcome the upward force (F2) of the nozzle needle
due to the larger surface area of the control valve.
• The control valve then moves downward effectively
closing the nozzle needle (5), blocking any fuel
from entering the combustion chamber.
F1x
F2x
6
1
2
4
5
8
6
7
2
3
5
4
F1
F2
1