Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
103
Section II. Maintenance Procedures
Fuel system of common rail engine consists of low-pressure delivery pipes and high-pressure oil pipes and maximum
pressure of it is over 1800bar. Some components of fuel injector and HP pump are machined with accuracy of 0.1mm.
Pressure regulation and fuel injection are controlled by engine ECU. In the case of stuck internal needle valve, fuel
injector will maintain open and HP pump keeps operating to supply high-pressure fuel oil. Therefore, excessive fuel
will be sprayed into combustion chamber and this will lead to rapid increase of combustion chamber internal pressure
(over 250bar) and even serious engine damage.
Core component of fuel system possesses very high accuracy and will be easily influenced by dust or tiny foreign
matters. Therefore, the following preparations and procedures should be carried out or there will be a lot of system
failures.
Operation Procedures:
1. It is necessary to keep maintenance site clean (it should be free of dust especially);
2. It is necessary to keep maintenance tools clean (they should be free of oil and foreign matters);
3. Wear ethylene pinafore to prevent hairs, dust and foreign matters from entering engine fuel system. Wash your
hands instead of wear gloves;
4. Prior to fuel system maintenance, carry out the following procedures:
5. If the fault is in HP pump, fuel delivery line or fuel injector, prepare clean special tools and sealing covers and carry
out relevant procedures for engine fuel system. Prior to maintenance, clean relevant areas to engine compartment
completely;
6. Find out faulted parts according to the above operation procedures and replace these parts with parts from OEM;
Carefully listen to customer’s description about
symptoms and faults
Check appearance and connection of wire harness
and connectors in engine compartment
Carry out test procedures with special diagnostic
apparatus (carry out road test when necessary)
Confirm the fault. If the fault is in fuel system,
please carry out Step1~3 above.
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