Page 55 - Foton Workshop Manual - Auman EST-M

Diagnosis - Fault diagnosis of electronic and electrical parts DI - 1
Fault diagnosis of electronic and electrical parts IN

Engine electric failure diagnosis

Overview DI
1. Instruction
EG
The fuel injection system of Commines ISF3.8 diesel engine adopts the electrical common rail fuel injection
system which mainly consists of high pressure oil pump, high pressure oil rail, injector, low pressure oil way,
etc. The electric control common rail fuel injection system of engine is used to meet stricter emission or noise TR
requirements and achieve lower fuel consumption rate by adopting higher fuel injection pressure, accurate
injection rate and injection capacity.
AX
2. Functions of fuel injection system

The fuel injection system is used to inject an appropriate amount of high-pressure fuel into combustion
FR
chamber at appropriate time, while ECM adjusts its fuel injection capacity automatically as per engine load to
ensure stable running of engine.
ST
3. High pressure common rail concept
a. High pressure common rail means several injectors share one high-pressure rail The pressure in the rail is
BR
established by the high pressure pump, which is up to 160MPa
b. The injection system eliminates the interplay between the pressure and fuel injection in the traditional oil
BW
supply system. The injection pressure will not be impacted by the engine speed and the injection quantity The
high pressure fuel produced by the high pressure pump is stored in the high pressure common rail and is ready
for injection at any time EL

c. Injection quantity, pressure and timing can be separately controlled according to the needs, which
thoroughly eliminates the impact of engine speed, circulating oil supply quantity, etc. In the meanwhile, up to
5 times multi-sectional injection can be realized, which makes the injection frequency more ideal

d. The work of common rail fuel injection system of diesel engine is fully controlled by ECM determines the
engine operating status according to the engine speed, vehicle speed, fuel rail pressure, boost intake pressure,
intake temperature, coolant temperature, fuel temperature, intake quantity and throttle position (i.e. driver’s
requirement) so as to accurately measure the fuel injection quantity and control the injection moment, time
and pressure
e. Comparing with the traditional diesel engine, the high pressure common rail electric system provide ideal
air/fuel mixing ratio for the engine. It improves greatly the noise, comfort, dynamic, emission,etc.
f. The system has failure diagnosis and protective function, which optimizes the engine performance and
improves the life of engine
Precautions

1. Safety Precautions
a. When performing service for the fuel system, pay attentions to fire-control measures. No smoking. Do not
perform service nearby fire. Diesel oil shall be far away from rubber or leather parts
b. The high pressure in the common rail diesel oil injection system is up to 160MPa. Prohibit releasing the
pressure with manual tools when the engine operates. Otherwise, it will shoot through a personal body and
cause danger and injury

DI-001