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Fuel Supply
to HFCM
Fuel Return
to Tank
Fuel Return
to HFCM
Fuel Supply
to Engine
To Filter/Pump
(suction side)
NOTE: Drilled Passage Hidden
Pump
Outlet
Fuel Return Directed via DTRM
to Tank or Back Through Pump
Fuel Cap
Fuel Filter
Fuel Pump
Fuel Inlet
Check Valve
DTRM
Manifold
Drain Valve
Fuel Pump
Power
Water In Fuel Sensor
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Fuel supply s y s t e m
HFCM (Horizontal Fuel Conditioning Module)
• The HFCM is mounted to the frame rail on the drivers side.
• The HFCM is a single module that performs multiple
tasks. It separates water from the fuel, senses
when water is present in the fuel, filters particulates
from the fuel, and creates the fuel flow needed to
supply fuel to the engine mounted fuel filter.
• A DTRM (Diesel Thermo Recirculation Module)
is also part of the HFCM. It recirculates fuel that
returns from the engine mounted fuel filter back
into the fuel filter instead of back to the tank.
HFCM Fuel Flow
• Fuel is drawn into the HFCM from the fuel tank via a
supply line.
• Fuel enters the filter housing via a one-way check valve.
• Once in the filter housing, water is separated from
the fuel. If large amounts of water are found in the
fuel, a sensor in the separator warns the operator of
this condition by illuminating a light on the dash.
• Fuel is then drawn through the 10 micron
fuel filter and into the fuel pump.
• Conditioned pressurized fuel is then supplied to the engine
mounted fuel filter via a fuel supply line. The pump has
an internal regulator that limits fuel pressure to 24psi.
• Fuel returning from the pressure regulator on the engine
mounted fuel filter comes into the HFCM and a DTRM
either allows the fuel to return to the tank or returns it
to the unfiltered side of the fuel filter in the HFCM. The
DTRM starts to open (recirculating fuel back into the
pump) at 80°F (27°C) and is fully open at 50°F (10°C).
HFCM Components
• The HFCM is composed of six (6) main components:
- Housing
- Fuel Filter (10 micron)
- Fuel Cap
- Electric Fuel Pump
- Manifold (contains the fuel inlet check valve)
- Diesel Thermo Recirculation Module (DTRM)
is also part of the HFCM. It recirculates fuel that
returns from the engine mounted fuel filter back
into the fuel filter instead of back to the tank.
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