Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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board due to water ingress of ECU.
5) Troubleshooting
Connect the plug and use engine data diagnosis cable to read the engine malfunction records; disconnect the plug and
check whether the ECU connecting wire is intact. Mainly check whether ECU power supply and grounding circuit are
normal, whether the external sensors are working normally, whether the output signal are reliable, and whether the
circuit is intact.
Check whether the actuators are working normally and whether their circuits are intact. Finally replace the ECU for
test.
III. Actuators
1. Fuel injector
1) Overview
The fuel injectors are located on the engine cylinder head and are mainly functioned to provide accurate fuel injection
for the engine at the correct moment.
2) Working Principle
To realize effective fuel injection start point and accurate injection amount, the common rail system adopts the special
fuel injector with hydraulic servo system and electronic control unit (solenoid valve). At the start of fuel injection
process, the fuel injector needs to adopt a relatively high current to rapidly open the solenoid valve. Till the needle
valve of the fuel injector nozzle reaches the maximum travel and the fuel injector nozzle is fully opened, the control
current is reduced to a relatively low constant current. In
such case, the fuel injection amount depends on the open
moment and the pressure in the common rail. When the
solenoid valve is no longer working and is closed, the fuel
supply process is completed.
The fuel injection start moment and the fuel injection
amount are regulated by the electronically controlled fuel
injector. These fuel injectors substitute the fuel injector
assembly (injector nozzle and fuel injector body). Similar to
the fuel injector assembly of modern direct injection diesel
engine, the holders are used to install the fuel injector on the
cylinder head. In other words, it’s unnecessary to make any
large modification to the cylinder head to install the
common rail fuel injectors onto the modern direct injection
diesel engine.
Design structure
The fuel injector (figure) can be divided into several
functional blocks:
- Injector nozzle
- Hydraulic servo system
- Solenoid valve
As shown in the figure, the fuel enters into nozzle through
high pressure connecting pipe (4) and fuel inlet groove (10)
and enters into the valve control chamber (8) through fuel
inlet (7). The control chamber is connected with fuel return
pipe (1) via fuel drainage hole (6) and the fuel drainage hole
Fuel injector
a. Close of fuel injector (Still state) b. Open of fuel injector (Fuel
injection)
1. Fuel return pipe 2. Electric connector 3. Control unit
(electromagnetic field) 4. Rail fuel inlet (high pressure) 5. Ball
valve 6. Fuel drainage hole 7. Fuel inlet hole 8. Valve control
chamber 9. Valve control plunger 10. Fuel inlet groove to
injector nozzle 11. Injector nozzle needle valve
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