Lifan 620 Maintenance Manual page 72

S/N
Connect the fuel pressure gauge valve. Short-circuit
the pin 30 and the pin 87 of the fuel bump relay, and
5
run the fuel pump. Check if the fuel pressure is about
300kPa.
Connect the battery and the fuel injector with a special
6
connector. With the voltage supply of 12V, check the
fuel injector for normal operation.
Wash the fuel injector and check the fuel injector
7
again for normal operation.
Replace the fuel. Check if the fuel is wrong or
8
contains water.
250kPa Check if the fuel pressure is lower than
9
250kPa.
Close the fuel gauge valve. Turn on the ignition
10 switch again and keep the fuel pump working for 3
seconds. Check if fuel pressure can be produced.
Turn on the fuel gauge valve, and block the fuel return
11
pipe. Check if the fuel pressure is quickly produced.
12 Check the fuel intake pipe for leakage or blockage.
13 Check if the fuel return pipe is blocked or bent.
Before the engine coolant reaches 35°C, take out the
14 idle speed actuator connector, and check if the
rotation speed of the engine is decreased.
Turn the ignition switch to ON. Check the voltage of
the following pins of the ECU. Is the voltage of the pin
15
J1-12 (crankshaft position sensor) is about 12V? Is
the empty pin and the pin J1-54 (idle speed stepper
motor A+) is 0V?
Keep the engine at idle speed. After the coolant
reaches normal temperature, ground the pin 51 of the
16
ECU with a short-connected line. Check if the ignition
advance angle is a 6.75° crank angle.
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Table 1-54 (Continued 1)
Operation
71
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Test Results Actions
Yes Next step
No 9
Yes 8
No Next step
Yes Next step
No Replace fuel injector
Yes Replace fuel
No 14
Yes Next step
No 13
Yes Next step
No 12
Replace fuel pressure
Yes
regulator
Repair or replace fuel
No
injector or fuel pipe
Repair or replace fuel intake
Yes
pipe
No Replace fuel pump
Repair or replace fuel return
pipe
Yes
Repair or replace fuel return
pipe
Replace fuel pressure
No
regulator
Yes Next step
No Replace idle speed actuator
Yes Next step
No Check harness and interface
Yes Next step
Adjust ignition advance
No
angle