Fuel Level Input (FLI)
WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 2012 Lincoln Navigator L, 2012 Lincoln Navigator, 2012 Lincoln MKZ, 2012 Lincoln MKX, and 2012 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.
The FLI is a communications network message. Most vehicle applications use a potentiometer type FLI sensor connected to a float in the fuel pump (FP) assembly to determine fuel level.