GM MDI troubleshoot Chevrolet Cruze Engine Fault

GM MDI Multiple Diagnostic Tool is an interface between the vehicle DLC and a PC (by wired USB, wired Ethernet, wireless Ethernet ) and TIS2web.
During driving, the engine fault light is on, but with no other abnormality.
A mileage of about 32,000 km, engine model LDE, 1.6L engine displacement of 2010 Chevrolet Cruze sedan.
Troubleshooting: technician check the car road test, during driving, the engine fault LED is lit, then try again to delete fault code, and fault indicator illuminates.
Then technician may consider:the problem of oil, spark plugs damaged canister valve damage and electromagnetic flow sensor is damaged.
You can use GM Scan tool to check the detailed problem.The system connection failure diagnostic GDS2 detection, fault code: P0172 fuel metering system is too thick. This fault code is common.Usually,the failure is: intake air flow sensor is damaged, the canister valve is damaged, poor quality gasoline, intake manifold check valve damage. Technicians and excluded one by one, which resulted in failure remains.
Check the data stream and found positive long-term fuel trim values ??as high as 23.5%. Remove the spark plug check and found that the spark plug is completely black, and not the original parts. Replacing the original spark plug, then clean the fuel system after the test, the data shows that long-term fuel flow correction value has not changed, but also increase the throttle throttle cleaning temper phenomenon, what is the fuel cleaning 300kP, caused by the pressure is not enough? The fuel pressure is applied to the original car standard 380kPa test, did not change.
Technicians analyze this phenomenon may have oil to gasoline vapor lock, fuel pump pressure limiting valve or judgment may be catching. Tests show that found in the fuel pressure gauge connected to start the vehicle fuel gauge pressure reaches a peak value.
After trying to replace the fuel pump assembly test, troubleshooting.
Fault summary: This fault is not complex, but the process should be paid particular attention that this case has a fault code, it is easy to mix with other symptoms with other faults, such as air filter is dirty or clogged , throttle and other blockage can also occur this DTC, are particularly vulnerable to misdiagnosis.