113 

 

No.063 Quick diagnosis for Hall sensor   

Hall effect

 

Principle of hall sensor

 

When the current I

S 

passes 

through semiconductor slice, 
hall voltage U

H

 will occur at 

right-handed rotation direction, 
which is proportion to 
magnetic field induction B 
(vertical to current I

S

) and 

current. Hall voltage is 
affected by induction strength 
B.

 

Hall element at (ON) status 

Hall  element  at  (LOCKED) 
status

 

 

 

 

U

V

 

U

V

 

U

A  

output voltage

 

U

V  

input voltage 

 

Low 

level 

High 
level 

 
 

 

 

114 

Diagnosis flowchart for Hall sensor (ignition distributor) 

 

1. Remove hall sensor, and measure resistance between 
terminal C of sensor joint and ground is between 0-2Ω? 

2. Ignition switch turned on, but unable to start the engine: 
measure voltage between terminal 3 and ground is between 
1.0-1.5V?  

3. Close ignition switch and remove ECU joint; measure 
resistance between terminal 1 of sensor joint and lines terminal 
48 of ECU joint is between 0-2Ω?

4. Measure resistance between terminal 1 of sensor joint and 
ground is infinitely large?   

5. Connect all joints, and clear malfunction code; as road testing, 
malfunction code is displayed?   

6. Replace hall sensor, and confirm malfunction code still exists 
after repairs are completed?   

7. Repair open circuit of lines between sensor and ground, and 
confirm repairs are completed?   

8. Repair problems such as open circuit or shorted to ground of 
lines between sensor and ECU, and confirm repairs are 
completed?  

9. Repair problems such as open circuit between sensor and ECU, 
and confirm repairs are completed 

10. Replace ECU   

Troubleshooting tip   

Y 

Y 

Y 

Y 

Y 

Y 

N 

N 

N

N 

N 

 
 

 

 

115 

 

No.064 Electric fuel pump EKP   

 

 
 
 
 
 
 
 
 
 
 

 
 
 

• Function: Transfer fuel from oil tank to the engine, and provide sufficient fuel pressure and rich 
fuel.  
• Principle: Fuel pump is vane pump driven by DC motor, and placed within oil tank and 
immerged by fuel, using fuel for heat emission and lubrication. The battery supplies power to 
electric fuel pump through oil pump relay, which will only switch on lines of electric fuel pump 
when started and the engine is running. When the engine stops running due to accidents, fuel 
pump will stop running automatically.   
• Mounting position:    Within fuel tank.   
Malfunction: Large running noise, poor acceleration, unable to startup (difficulty startup), etc.   
General causes: Due to uses of poor quality fuel, it will cause: 1. formation of insulating layer due 
to colloid accumulation; 2. locking of oil pump bushing and armature; 3. corrosion of oil level 
sensor elements, etc.     
Maintenance precautions: 1. according to needs of the engine, electric fuel pump is with different 
flows. Even mountable fuel pump with the same appearance is not proper. For maintenance, 
number of part of fuel pump shall be consistent with original one; 2. to prevent damages of fuel 
pump, do not operate it under dry condition for a long time; 3. if fuel pump is to be replaced, 
clean fuel tank and pipes and replace fuel filter.   
Simple measuring method: 
(remove the connector) Place digital multimeter to ohm position, and two pens are respectively 
connected to two pins of fuel pump, and measure internal resistance, which shall not be zero or 
infinite (i.e. non-short-circuited, off state).   
(connect the connector) for oil return system, connect the fuel pressure gauge at oil sucker, and 
start the engine, making it operate at idling speed status. Fuel pressure of the engine shall be 
around 260kPa at this time; take out vacuum tube of fuel pressure regulator, and fuel pressure 
shall be around 300kPa at this time.   

1.  Oil pump end 

cover  

2. Armature 
3. Oil 

duct 

4. Impeller  

 
 

 

 

116 

Diagnosis flowchart of oil pump circuit 

 

1. Check fuse of oil pump relay is open circuited?   

2. Close inigtion and remove fuel pump relay: ignition switched on, and 
voltage of terminal 85, 30 of relay is larger than 10.7V?   

3. Remove ECU joint, and measure resistance of lines between ECU 
terminal 3 and fuel pump relay is lower than 0.5Ω? 

4. Measure resistance between ECU terminal 3 and ground is infinitely 
large?

5. Measure resistance of relay coil (85-86) is about 80-90Ω? 

6. Check lines between fuel pump and fuse, and oil pump relay are 
normally connected?   

7. Replace ECU and confirm repairs are completed.   

8. Repair “shorted to ground” of fuse of fuel pump relay, and confirm 
repairs are completed?   

9. Repair malfunctions such as open circuit, short circuit of relay, fuse, 
power supply, and confirm repairs are completed?   

10. Repair short circuit of lines between relay and ECU, and confirm 
repairs are completed?   

11. Replace oil pump reay, and confirm repairs are completed?   

Repairs  

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

N

N 

N 

N 

N 

N 

Y