ENGINE FUEL SYSTEM
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1881-01
Fuel Line System
Fuel route
2. COMPOSITION OF FUEL SYSTEM
Components in fuel system are designed to generate and distribute high pressure, and they are
controlled electronically by engine ECU. Accordingly, fuel system is completely different from
injection pump type fuel supply system on the conventional Diesel engine. The fuel injection
system in common rail engine is composed of transfer pressure section that transfers fuel in
low pressure, high pressure section that transfers fuel in high pressure and ECU control
section.
High pressure pipe
Common rail
Fuel pressure
sensor
Priming pump
Fuel pump
(High pressure pump, transfer pump)
Fuel filter
Injector
D20DT: 4 EA
D27DT: 5 EA
common rail
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1881-01
ENGINE FUEL SYSTEM
3) High Pressure Pipe (Fuel Pipe)
Fuel line transfers high pressure fuel.
Accordingly, it is made of steel to endure
intermittent high frequency pressure
changes that occur under maximum system
pressure and injection stops. Injection lines
between rail and injectors are all in the same
length; it means the lengths between the rail
and each injector are the same and the
differences in length are compensated by
each bending.
4) Injectors
The fuel injection device is composed of
electrical solenoid valve, needle and nozzle
and controlled by engine ECU. The injecto
r
nozzle opens when solenoid valve is
activated to directly inject the fuel into
combustion chamber in engine. When
injector nozzle is open, remaining fuel afte
r
injection returns to fuel tank through return
line.
Pressure limit valve, fuel returned by low
pressure and fuel used for high pressure
pump lubrication also return to fuel tank
through return line.
6) Fuel Filter Replacement
Fuel filter change interval: every 30,000 km
Water separation interval: every 10,000 km (same with engine oil change interval)
Never reuse the removed fuel filter -
-
-
The transfer pump is included in the housing
of the high pressure pump. The transfe
r
pump is the volumetric blade type pump. To
deliver the continuously required fuel
volume, the pump transfers fuel from the fuel
tank to high pressure pump.
5) Transfer Pump
