There is no fuel reset button on a 2000 Ford Expedition (or any car for that matter) to reset the fuel gauge or fuel economy calculations. The fuel gauge shows the level of fuel in the tank directly from the fuel level sensor. The fuel economy calculations are handled by the onboard computer and reset automatically under certain conditions (like when the fuel tank is filled). There is no user-accessible button to manually force a reset.
If your fuel gauge is inaccurate, you likely have a problem with the fuel level sensor itself, the wiring to the sensor, or the instrument cluster. If your fuel economy calculations seem off, there's no user reset; the computer will recalculate based on your driving.
