Fuel Gauge Problem - Blame the Gas Pump

[Car Nut]

Those of you who experience the fuel gauge not registering full after filling up at the gas station should not immediately conclude that the MB fuel gauge sending unit is the culprit.

I have been experiencing the problem lately. I found out that the gas pump auto shut off is too sensitive. It shut off prematurely. I did an experiment to prove it. I filled up the tank at one gas station. Of course, the fuel gauge was 1/8 below the full or about 2.5 gallon less . I drove on the highway for 80 miles. I filled it up at another gas station. This time the fuel gauge registered full, but it took about 6 gallon. If that was true, it meant my 1999 E430 MPG was about 13. I believed the real gasoline usage was about 3.5 gallon and translated to about 23 MPG. Therefore the tank was 2.5 gallon short in the beginning. The fuel gauge was registered accurately.

Car Nut
99 E430 Sport

In my owners's manual, the gas gauge is refered to as a ''fuel level indicator''. It gives an indication, which is not necessarily an accurate measurement.
JackD

[tecqboy]

In an attempt to cut down on spilled gasoline and the resulting polution, the EPA has required the shut off pressure to be set to a more sensitive condition. They also post a sign which ask you to please NOT top off your tank. In any case, the pump will almost always shut off as son as any back pressure is detected. I still top my tank off. Tod