New Holland SmartTrax T8.320 Service Manual page 50

Fuel system Components
Pressure regulator
Located on the high pressure pump, it regulates the
amount of fuel supplied to the high pressure pump on
the basis of signals received from the Engine Control
Unit (ECU) by modulating the duty-cycle. This allows
pressure variation inside the common rail.
The pressure regulator is normally open. The high pres-
sure pump is therefore in maximum delivery mode if no
signal is sent by the ECU unit.
The regulator is Pulse Width Modulated (PWM); it re-
ceives 12 V (battery voltage) from the ECU. The ECU
completes and varies the current by controlling the
ground. The regulator is not polarity sensitive. Resis-
tance if checked should be about 3.2 Ω.
Common rail relief valve
The common rail relief valve is mounted on the end of the
common rail. It functions to protect the system's compo-
nents in case of a failure of the rail pressure sensor or
the pressure regulator that could cause the high pressure
pump to provide more fuel than the system can safely han-
dle.
The common rail relief valve is a two stage valve. When
the rail pressure reaches 2000 bar (29000 psi), the valve
opens and will drop the common rail pressure to approx-
imately 1000 bar (14500 psi). This allows the engine to
be operated but at reduced power.
Low pressure gear pump
RAIL15TR00372AA
(A) Supply fuel drawn from pre-filter
(B) Supply fuel to final filter
(1) Fuel supply relief valve 5.0 bar (72.5 psi)
(2) Supply pump bypass valve (for bleeding)
Engine - Engine and crankcase
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RAIL15TR00373AA
RAIL15TR00368AA
The fuel supply transfer pump is a gear pump located on
the back of the CP3 high pressure pump. The transfer
pump is shaft driven off the CP3 high pressure pump
shaft.
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