fuel pressure SSANGYONG NEW REXTON 2012 Owner's Manual

2210-01
How To Use Pressure Tester
Press the "TEST" button on the tester to
check if the message "TEST?" is displayed.
If the button is pressed again at 4 seconds
after starting engine cranking, the highest
pressure is displayed on the tester. 1.
2.
The fuel rail pressure value can be checked using a diagnostic device.

(6) Low Pressure System Pressure Test
Inspection procedure
All wirings/connectors and fuel lines should be
connected and the engine should work
properly.
Prepare a special tool for low pressure test
and clean it thoroughly to prevent foreign
materials from entering. 1.
2.
Disconnect the key connector for fuel filter connection, and connect both connectors to the fuel filter
and hose. 3.
Start the engine and check visually for clogged low pressure fuel system, excessive air or air entry.
If the fuel flow is not sufficient or air is in the fuel, repair the leak area. 4.
5.

2210-01
Static test for backleak of injector
Disconnect the injector return hose and cover
the openings with caps shaped screw (included
in the special tool). 1.
Connect the hose of the container for
measuring backleak to the return nipple of the
injector.
(prevent air entry to the low pressure line) 2.
Disconnect the IMV connector of the high
pressure pump and then fuel pressure
sensor connector. 3.
The connector of the injector can be easily
contaminated. Always keep it clean.
Crank the engine 2 times for 5 seconds.
Check the time for flow if injector backleak and
confirm that it is within the specified range. 4.
5.
If the value is out of the specified range,
replace the injector.
SpecificationBelow 20 sec.

2210-01
HP pump pressure test
Prepare a special tool for high pressure test
and clean it thoroughly to prevent foreign
materials from entering. 1.
Disconnect the high pressure fuel supply pipe
on the HP pump and install the close rail in the
tool kit. 2.
Connect the other end of the close rail to the
fuel rail for test. 3.
Disconnect the return hose for HP pump and
connect the clear hose and connect its the
other end to the return port of the fuel rail for
test. 4.
Connect the digital tester connector to the
sensor connector of the fuel rail for test.
Crank the engine 2 times for 5 seconds after
removing the IMV connector and fuel rail
pressure sensor connector.
Read the pressure value displayed on the
tester display is within the specified 5.
6.
7.
Specification1,050 bar or more

2210-01
2) Cleanness
(1) Cleanness of DI engine fuel system
Cleanness of DI engine fuel system and service procedures
The fuel system for DI engine consists of transfer (low pressure) line and high pressure line.
Its highest pressure reaches over 1,800 bar.
preciseness.
The pressure regulation and injector operation are done by electric source from engine ECU.
Accordingly, if the internal valve is stuck due to foreign materials, injector remains open.
Even in this case, the HP pump still operates to supply high pressurized fuel. This increases the
pressure to combustion chamber (over 250 bar) and may cause fatal damage to engine.
You can compare the thickness of injector nozzle hole and hair as shown in below figure (left side). The
below figure shows the clearance between internal operating elements.
The core elements of fuel system has very high preciseness that is easily affected by dust or very small
foreign material. Therefore, make sure to keep the preliminary works and job procedures in next pages.
If not, lots of system problems and claims may arise.
Hair
Nozzle holeValve actuator lift - 0.028 mm
Diameter
0.04 mm
Operating
clearance
0.002 mm
Diameter
2.0 mm

(2) Di engine and its expected problems and remedies can be caused by
water in fuel
System supplement against paraffin separation
In case of Diesel fuel, paraffin, one of the elements, can be separated from fuel during winter and then
can stick on the fuel filter blocking fuel flow and causing difficult starting finally. Oil companies supply
summer fuel and winter fuel by differentiating mixing ratio of kerosene and other elements by region and
season. However, above phenomenon can be happened if stations have poor facilities or sell improper
fuel for the season. In case of DI engine, purity of fuel is very important factor to keep internal
preciseness of HP pump and injector.
Accordingly, more dense mesh than conventional fuel filter is used. To prevent fuel filter internal clogging
due to paraffin separation, SYMC is using fuel line that high pressure and temperature fuel injected by
injector returns through fuel filter to have an effect of built-in heater (see fuel system).
System supplement and remedy against water in fuel
As mentioned above, some gas stations supply fuel with excessive than specified water. In the
conventional IDI engine, excessive water in the fuel only causes dropping engine power or engine
hunting. However, fuel system in the DI engine consists of precise components so water in the fuel can
cause malfunctions of HP pump due to poor lubrication of pump caused by poor coating film during high
speed pumping and bacterization (under long period parking). To prevent problems can be caused by
excessive water in fuel, water separator is installed inside of fuel filter. When fuel is passing filter, water
that has relatively bigger specific gravity is accumulated on the bottom of the filter.
Water drain from water separator
If water in the separator on the fuel filter exceeds a certain level, it will be supplied to HP pump with fuel,
so the engine ECU turns on warning lamp on the meter cluster and buzzer if water level is higher than a
certain level.
Due to engine layout, a customer cannot easily drain water from fuel filter directly, so if a customer
checks in to change engine oil, be sure to perform water drain from fuel filter.
Water
separator
To separate the water from the fuel filter,
remove the fuel filter assembly first.

2210-01
1. OVERVIEW
The components in fuel system supply the fuel and generate the high pressure to inject the fuel to each
injector. They are controlled by the engine ECU.
The common rail fuel injection system consists of fuel tank, fuel line, low pressure line which supplies low
pressure fuel to the low pressure pump (including high pressure pump), common rail which distributes
and accumulates the high pressurized fuel from the fuel pump, high pressure line which connected to
the injector, and the engine control unit (ECU) which calculates the accelerator pedal position and
controls the overall performance of vehicle based on the input signals from various sensors.
1) Fuel Flow Diagram

2210-01
Accelerator pedal position
sensor
Detecting driver's intention
for speed up/down
Fuel rail assembly
Relieving the pulsation.
Measuring the fuel pressure.
Distributing the fuel to injectors.
Fuel filter assembly
Supplying clean fuel/fuel
heating/water separation by
priming pump
Plunger type HP pump (1,800 bar)
Vane type LP pump (6 bar)
T-MAP sensor
Measuring booster pressure
and temperature
High pressure pump
Generating high pressurized fuel and
supplying it according to engine rpm,
required volume, required pressure

2) Fuel System Flow Diagram
The fuel from the fuel tank is supplied to the fuel heater of fuel filter/priming pump and then low pressure
generated by the low pressure pump (built into HP pump) is transmitted to the HP pump.
The fuel pressure at the HP pump is controlled by the IMV valve, and the maximum allowed pressure is
1,800 bar. The compressed fuel at the fuel pump is delivered to the rail, and injected by the injectors
according to the injection signals. The injection method is the same with the conventional method; Fuel
return by backleak which operates the needle valve.
The major difference is that the fuel return line is connected to the fuel filter inlet port, not the HP pump
venturi.
The pressure from the high pressure pump is increased to 1,800 bar from 1,600 bar, and the pump is now
installed to the cylinder head (cylinder block for previous model). The fuel pressure is generated by the
operation of intake camshaft and gears. The specifications for the IMV valve and the fuel temperature
sensor are not changed.

The engine ECU calculates the accelerator pedal based on the input signals from various sensors, and
controls the overall operation of the vehicle.
The ECU receives the signals from various sensor through data line, and performs effective air-fuel ratio
control based on these signals.
The crankshaft speed (position) sensor measures the engine speed, and the camshaft speed (position)
sensor determines the order of injections, and the ECU detects the amount of the accelerator pedal
depressed (driver's will) by receiving the electrical signals from the accelerator pedal sensor.
The mass air flow sensor detects the volume of intake air and sends the value to the ECU.
The major function of the ECU is controlling air-fuel ratio to reduce the emission level (EGR valve control)
by detecting instantaneous air flow change with the signals from the mass air flow sensor.
Also, the ECU uses the signals from the coolant temperature & air temperature sensors, booster pressure
sensor, atmospheric pressure sensor to: a) determine injection starting point and set value for pilot
injection, and b) deal with various operations and variable conditions.