ZONGSHEN ZS125-86 Service Manual page 24

The oxygen sensor mounted on the exhaust pipe of the engine is an important landmark part of the
closed-loop fuel control system. The main sensitive material of the oxygen sensor is zirconia. When the
zirconia is heated and activated by exhaust gas (300°C), oxygen ions pass through the zirconia element
to reach its external electrode. The zirconia element senses the oxygen content of the engine exhaust and
changes its output voltage value.
The oxygen sensor uses teflon insulated wire and stainless steel formed elements. Reference air is input
by the wire, without any blocking problem.
When the ratio of air to fuel that involved in engine combustion is increased, the oxygen concentration
in the exhaust gas increases and the output voltage of the oxygen sensor decreases. Conversely, the output
voltage increases, thereby feeding real-time engine air-fuel ratio back to the ECU.
2. Demolition and Maintenance of EFI System
The motorcycle EFI system has been commissioned before leaving the factory. If any failure of the EFI
system, it is strictly forbidden to adjust the idle-speed screw on the throttle valve body by oneself, and it is
not permitted to replace or adjust the EFI system parts by oneself. If any questions, please visit our special
maintenance service station for maintenance.
The motorcycle EFI system has an EFI malfunction indicator lamp on the dash board. When the
ignition system circuit opens, the indicator lamp keeps bright under normal working conditions; if there is a
fault, the lamp does not work. When the engine starts, the indicator lamp goes out under normal working
conditions; if there is a fault, the lamp keeps bright or flashes.
Target wheel on
24X crankshaft
position
Heating-type oxygen sensor
Engine temperature sensor
Intake air temperature
/pressure Integrated
sensor
Zero position switch
Dumping switch
Ignition Switch
Storage battery
3. Common Faults of EFI System
The fault diagnosis device is used to check the EFI system for any fault information. If any fault, then
install corresponding new EFI parts; if no fault, please check for the following items:
1.Check whether the lines are connected properly, with or without any damage;
2.Check whether the voltage reaches more than 9V;
3.Check whether the vehicle fuse and EFI fuse are damaged;
4.Check whether the oil channel is proper, and whether the oil tube is blocked, squeezed and damages,
18
to ensure smooth oil flow.
Crankshaft position sensor
Malfunction
indicator
lamp
Structural Schematic Diagram for EFI System
Throttle position sensor
Burglar alarm
Optional
ECU
Fault diagnosis switch
Serial communication interface
Engine
Engine high-
speed
temperature
电喷系统的结构原理图
signal
indicator
Optional
I d l e c o n t r o l
valve
Optional
Throttle valve body
Ignition coil
IgniM3.5
nozzletion coil
WCRR oil
pressure
regulator
oil pump
three-way catalyst