The fuel level sender is part of the fuel pump. It is entirely possible (and don't ask how I know this) that the rod with the float on the end could become tangled in the fuel lines inside the tank, resulting in the float getting stuck in the "up" or full position. MB has just come out with some new updates concerning the fuel pump assembly and also some external hose changes for the ML, your dealer will probably want to do these updates now also. Bulletin was released about a week ago concerning both of these changes........Gilly