Page 318 of 600
2. MAINTENANCE AND INSPECTION
1) Maintenance Procedures for DI Engine Fuel System
Always keep the workshop and lift clean (especially, from dust).
Always keep the tools clean (from oil or foreign materials).
Wear a clean vinyl apron to prevent the fuzz, dust and foreign materials from getting into fuel system.
Wash your hands and do not wear working gloves. 1.
2.
3.
Follow the below procedures before starting service works for fuel system.
If the problem is from HP pump, fuel supply line or injector, prepare the clean special tools and sealing
caps to perform the diagnosis for DI engine fuel system in this manual. At this point, thoroughly clean
the related area in engine compartment. 4.
Clean the engine compartment before starting service works.
Tool kit for high pressure lineTook kit for low pressure line
Page 319 of 600

2210-01
Priming pump cap
Follow the job procedures. If you find a defective component, replace it with new one. 5.
Once disconnected, the fuel pipes between HP pump and fuel rail and between fuel rail and each
injector should be replaced with new ones. The pipes should be tightened tospecified tightening torques
during installation. Over or under torques out of specified range may cause damages and leaks at
connections. Once installed, the pipes have been deformed according to the force during installation,
therefore they are not reusable. The copper washer on injector should be replaced with new one. The
injector holder bolt should be tightened to specified tightening torque as well. If not, the injection point
may be deviated from correct position, and it may cause engine disorder.
Plug the removed components with clean and undamaged sealing caps and store it into the box to
keep the conditions when it was installed. 6.
To supply the fuel to transfer line of HP pump
press the priming pump until it becomes
hard. 7.
Priming pump
Fuel filter assembly
Check the installed components again and connect the negative battery cable. Start the engine and
check the operating status.
With Scan Tool, check if there are current faults and erase the history faults. 8.
9.
Page 320 of 600
2) Diagnostic Test for Engine Fuel System
(1) Overview
If a DTC is displayed on the diagnostic device, check the low pressure- and high pressure fuel systems
before removing the components.
To run the system properly, the electric system must be intact but for the DI engine, the fuel pressure
should be measured also when there is a malfunction even after the diagnostic test with a diagnostic
device.
(2) Hydraulic system
Page 322 of 600
(4) Loss of pump pressure/flow
Loss of HP pump pressure/flow
Faulty fuel supply line, or damaged or worn pump causes the lack of flow pressure and flow volume
Example:
Air in fuel supply line
Burned out and mechanical worn pump
-
-
-
-
Page 323 of 600
2210-01
3) DI Engine Fuel System Pressure Test
(1) Test device (Tool kit)
Device for high pressure
Device for low pressure
(2) Pre-check
Check-tighten fuel supply line
Check fuel level in fuel tank
Check air in fuel supply line (bubble in fuel supply line or fuel)
Check fuel supply line for leaks (low pressure and high pressure)
Check that specified fuel is used
Check fuel filter for contamination -
-
-
-
-
-
Page 324 of 600
(3) DI Engine Fuel System Check Procedure
If several DTCs are output simultaneously, check the electric wiring for open or short circuit.
Check the low pressure fuel system and fuel filter and confirm that there are no abnormalities. Carry
out the high pressure fuel system check.
Page 325 of 600
2210-01
(4) Fuel System Check Procedure
Page 326 of 600
(5) High Pressure System Pressure Test
Fuel rail pressure test
Disconnect the fuel rail pressure sensor
connector and then IMV connector. 1.
Connect the pressure tester to the fuel rail
pressure sensor connector. 2.
Crank the engine 2 times for 5 seconds. 3.
Read the highest pressure value displayed
on the tester display.
If the highest pressure value is 1,050 bar or
less, refer to the section "Fuel System
Check Process". -
-