Hi,
I have a 2002 E39 525d touring, and I have A problem since last November. When there is about 20-25 liters in the fuel tank, DDE light comes up, the engine stops within the next 5 km.I looked under the hood and saw that was air in the diesel line just like there was no fuel left in the tank. I went to the BMW service for the diagnose and they run a test with the results: The fuel gauge is OK, but the transfer pumps are defective, so they replaced the electrical pump in the right side and the transfer( basically some plastic tubes) pump running from right to the left tank. I filled up and drove till empty ONLY ONCE, after that the problem reappeared!!! Went back to the service, they said now that the I need to change the fuel tank, they cannot explain why. I went to other service they checked all the fuel pumps,fuel lines,fuel sensors etc, they are all OK and AIRTIGHT. The problem is that under a certain fuel level the pump aspirates air from the right tank and the fuel system does not aerate anymore. Did anybody have a similar problem? What is the fuel transfer scheme?