A BMW 523Li made 2012 with 3100 miles,the owner discribed that due to continuous flameout when running,so this drove to my garage for repairing.And the owner feedbacked that he can restart engine after flameout.
Trouble Diagnosis:
Before diagnosing,technicians confirm the vehicle had enough fuel in the fuel tank.Then technicians used the ISID to read out DTC ”EKPS481B02:fuel pump with high control current”.Fault frequency 6 times,currently does not exist.
The trouble description show as below:
| Trouble Describtion | If adjust current(phase position A) greater than 18 A,then identify trouble |
| Trouble identify condition | BUS terminal KL.30 between 9v~18v
BUS terminal KL.15 switch on BUS terminal KL.30 switch on Can not active diagnostic mode |
| DTCs stored record condition | Delete trouble record:4s |
| Trouble effects and drop anchor description | None |
| Maintenance measures | Possible cause of the malfunction：
*wire harness *EKPS fuel pump control *fuel tank *query trouble according to testing |
| Driver info | Check control info(309):fuel pump |
| Service prompt |
In order to keep enough fuel supply,ECU sent a massage which include quantity demanded to the fuel control system by CAN-BUS.This demanded massage describes the rated delivery (speed adjustment),or the pulse width modulation specification(pressure regulation).In the speed adjustment,ECU sent a massage which include quantity demanded(unit:L/h).All control progress is called fuel pump electronic adjustment.
Fuel pump electronic adjustment system will control the electronic fuel pump according to the demand.The DME control module will caculate the amount of the fuel required of engine every moment.And this fuel quantity demanded info will be sent to EKPS fuel pump control system.Then EKPS will adjust the power of the electric fuel pump,so that electric fuel pump to transport accurately the required amount of fuel.The fuel pump electronic conditioning system optimizes the fuel supply and reduces fuel consumption.
Fuel pump electronic adjustment system functions:
1. Transport the fuel by demand
2. Diagnosis of fuel low-pressure system
3. Emergency operation (full power trigger fuel pump) when CAN communication problems occur
4. Electric fuel pump cooling and lubrication
According to the trouble syptoms to perform diagnostic plan:
1.Checked the wire connection between fuel pump and EKPS,it was normal.
2. Perform fuel pump function detection,kept fuel pump working 20s,it work correctly,but it can not prove that the fuel pump have kept working correctly.
The vehicle only traveled 5000km, the frequency of failure occurred 6 times, there is reason to suspect that the fuel pump most likely work incorrectly, so it need to replace the fuel pump to solve this problem.
After replacing fuel pump,the flameout syptom is disappeared.