1 2 3 45-124replacing air cleaner, always ensure that no dirt enters air duct, never
use ungraded air cleaner.
(2) Simple measuring method:
(Remove joint) turn digital multimeter to ohm position, connect
two meter pens with regulator pin 1, 4 and 2, 3 respectively. Rated
resistance between 1, 4 and between 2, 3 at 20°C should be about
43.2 ohm.
9. Fuel injector
(1) ECU energizes coil of fuel injector to form magnetic field force. When magnetic field force increases to
sufficient to overcome pressure of return spring, gravity of needle valve and resultant force of frictional force,
needle valve begins to rise, oil injection process begins. When oil injection impulse cuts off, pressure of return
spring closes needle valve again.
Symptom
Poor idle speed, poor speedup, failure to start
(difficult to start)Possible cause
Since lack of maintenance, gum builds up in
fuel injector and leads to malfunction
Repair precautions:
1. there are many kinds of fuel injector, their appearance is the same, mountable fuel injector may not be the
exactly suitable one, part number of fuel injector used in repair must be consistent with original fuel injector, wrong
replacement is not permitted;
2. To facilitate installation, it is recommended to apply silicon free clean engine oil on O ring surface at upper
part connecting distributing pipe of fuel oil. Pay attention not to let engine oil contaminate fuel injector inside and
jet orifice;
3. To remove and reinstall fuel injector, O ring must be replaced, here do not damage sealing surface of fuel
injector;
4. if fuel injector has two slots, when mount buckle clamp, pay attention not to clamp in the wrong position,
refer to mounting position of original parts;
5. It is strictly prohibited to remove strainer, clean or replace strainer at discretion; 6. after removal, ensure
cleanness of fuel injector holder, avoid foreign matter ingressing the cylinder.
Simple measuring method:
(Remove joint) turn digital multimeter to ohm position, connect two meter pens with fuel injector pins
respectively, rated resistance at 20°C is 11-17 ohm.
Suggestion: use special cleaning analyzer to conduct thorough cleaning for the fuel injector per 20000km.
10. Electric fuel pump
(1) Fuel pump is a vane pump driven by DC motor, is placed in oil tank, immersed in fuel oil, utilizes fuel oil
for heat dissipation and lubrication. Storage battery supplies power to electric fuel pump via oil pump relay, the
relay switches on electric fuel pump circuit only at the time of startup and during operation of engine. When engine
shuts down due to accident, fuel pump stops running automatically.Symptom
Large running noise, poor speedup, failure to start
(difficult to start)Common cause
1. Gum builds up to form insulating layer;
2. Oil pump bushing is blocked with armature;
3. Fuel level sensor assembly is corroded etc.Engine EFI System-Engine EFI System
Symptom
Poor idle speed, malfunction etc
Symptom
Fail to start5-125 Repair precautions:
1. according to engine requirement, electric fuel pumps with different flows are available, they have the same
appearance, mountable fuel pump may not be exactly suitable, during repair, part number of fuel pump used must
be consistent with original one, wrong replacement is not permitted;
2. in order to prevent fuel pump from damaging, please do not run it in dry state for a long time;
3. in case fuel pump needs to be replaced, please pay attention to clean fuel tank and pipeline and replace fuel
filter.
(2) Simple measuring method:
(Remove joint) turn digital multimeter to ohm position, connect two meter pens with fuel pump pins
respectively, measure internal resistance, it should not be zero or infinite (namely not in short circuit, open circuit
condition).
(Connect joint) connect fuel pressure gauge on sucker, start up engine, run the engine at idle speed, now fuel
pressure of engine should be about 260kPa; unplug fuel pressure regulator vacuum tube, now fuel pressure should
be about 300KPa.
11. Canister control valve
(1) Canister in fuel evaporation control system adsorbs oil vapor from oil tank until saturated. Electronic
control unit controls opening of canister control valve, fresh air and saturated fuel vapor in canister form
regeneration stream, which is led into engine intake pipe again. Electronic control unit changes duty ratio of pulsing
signal to canister control valve solenoid according to different operating conditions of engine, thus controls flow
of regeneration stream. In addition, this flow is also influenced by pressure difference at both ends.
Possible cause
Entering of foreign matter into valve inside results in
corrosion or poor leak tightness etc
Repair precautions:
1. To install, airflow direction must meet the specification;
2. when black granules inside valve body result in malfunction of control valve, and control valve needs to be
replaced, please check the condition of canister;
3. avoid water, oil etc liquids from entering valve as far as possible during repair;
4. in order to avoid transfer of solid-borne noise, it is recommended to install canister control valve suspending
on the hose or use soft rubber to fix.
(2) Simple measuring method:
(Remove joint) turn digital multimeter to ohm position, connect two meter pens with canister control valve pins
respectively, rated resistance at 20°C is 22 - 30 ohm.
12. Ignition coil
(1) When earthing channel of primary winding is connected, this primary winding is charged. Once ECU cut
off primary winding circuit, charging stops, high voltage is induced in secondary winding at the same time, so spark
plug discharges. Ignition coil ZSK 22 (both ends of 2 secondary windings are connected with a spark plug
respectively, so these two spark plugs ignite simultaneously.
Possible cause
Too heavy current leads to burnout, damaged by external force Repair precautions: it is prohibited to use "short circuit ignition testing method" to test ignition function, soEngine EFI System-
Engine EFI System
