Good Evening,
I have a '99 E300 and have been having an excessive fuel consumption problem. After going through the injectors and fuel lines I have found the cause: Diesel is sitting at the brim of the fuel filler neck and spilling out when turning. Filler cap is on tight and does not appear to be defective. When I open the filler cap there is no vacuum that's being released either. I went on the online interactive Mercedes parts catalog to see the fuel tank part diagrams to see if maybe the return line was above the shut-off valve for some reason or if the EVAP system might be clogged. Fuel return is on the bottom of the tank and there does not appear to be an EVAP system on the w210 E300 at all! I am completely stumped on what could be causing this problem. Talked to both dealership techs and Mercedes-certified independent shop techs and both were stumped. If anyone could shed some light on this that would be greatly appreciated!