SsangYong Actyon Sports II. Manual - part 25

03-20

(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.

03-21

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

03-22

2. SYSTEM LAYOUT AND OPERATION

1) Layout

For sensor and actuator control logic, refer to Chapter "Engine Control".

Engine ECU (D20DTR)

Engine control by various 
signals

Fuel tank

Fuel metering by sender

HFM sensor

Measuring intake air mass and 
temperature

Crankshaft position sensor

Measuring engine rpm

Injector (C3I)

Pre-injection, main injection, 
after-injection by signals from 
ECU

Camshaft position sensor

Determining injection order

03-23

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