How to solve the problem of BMW 318i not starting  

 (1) Fault symptoms: The chassis model of this car is E46, equipped with an M43 engine. The fault 

symptoms are as follows: when the engine is started, there is no sign of the engine starting, and the fuel 

gauge on the instrument panel indicates zero. 

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  (2) Diagnosis and maintenance. Remove the rear seat and the two flanges on the upper part of the fuel 

tank. It is found that there is no fuel in the right oil storage chamber, but the left oil storage chamber is full 

of fuel. This condition is usually caused by a damaged siphon mechanism inside the fuel tank. Taking 

out the siphon device, it can be seen that it is a simple siphon device with only a siphon pump and a 

connecting tube. After careful inspection, it was confirmed that there was no problem with the siphon 

device. Analyzing the cause of the failure, it may be insufficient fuel return pressure. After replacing 

the fuel filter and fuel pump, test drive and completely eliminate the fault.  

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(3) Summary The fuel pump is installed in the oil storage chamber on the left side of the fuel tank.

  During engine operation, excess fuel returns to the left oil storage chamber of the fuel tank, and is 

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pumped to the right oil storage chamber through the siphon device for recycling. Fuel requires a certain 

initial pressure when it returns, and the pressure comes from the fuel pump. Therefore, if the fuel pump 

performs poorly or the fuel filter is clogged, a fault like this will occur.