HI PRESSURE FUEL SHUTOFF
SOL
DESCRIPTION
The high pressure fuel injection pump has a inte-
grated shut off valve for one of the high pressure
pump elements. The ECM monitors the fuel temper-
ature and will switch off the element if the fuel tem-
perature reaches above 287°F (120C) with the engine
speed above 2200 rpm. The shut off valve is not ser-
viced separately.
OPERATION
The high pressure injection pump element shut off
valve interrupts the fuel high pressure delivery of
one of the injection pump elements in the part load
range. This will reduce the power required for driv-
ing the high pressure pump so as to reduce the fuel
temperature. The pump element is switched off if the
fuel temperature is excessively high forcing it to
return again to the fuel feed to cool. The element
shut off limits the increasing pressure of the injection
pump to ensure that the critical fuel temperature for
the system is not exceeded.
WATER IN FUEL SENSOR
DESCRIPTION
The water in fuel sensor if located in the bottom of
the fuel filter housing. This sensor detects the pres-
ence of water in the fuel. If water is present in the
fuel a signal is sent to the ECM and the ECM signals
the instrument cluster, over the CAN bus, to illumi-
nate the water in fuel warning.
OPERATION
The non-dielectric properties of the water allow the
sensors probes to close the electronic circuit when
water is present in the system. When diesel fuel is
present in the system, it’s dielectric (does not conduct
electricity well) properties do not allow any electrical
contact between the probes. A 12V power signal is
always present in order to illuminate the indicator on
the instrument cluster. For removal and installation
procedure refer to (Refer to 14 - FUEL SYSTEM/
FUEL DELIVERY/FUEL FILTER - REMOVAL).
14 - 16 FUEL DELIVERY VA
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