The FSM maintains awareness of an aircraft's fuel supply situation every second of a flight by continuously reading fuel system sensors including level, flow and pressure sensors as well as electrical pump activations.
With this awareness the FSM will detect situations such problems (whether developing or immediate) and annunciate them in a timely manner to the pilot/cockpit crew directly via warning and/or other instrument panel lights.
The FSM will also perform automatic fuel leveling/selection by controlling two fuel pumps, this to maintain the aircraft's lateral (or longitudinal) balance by directing fuel to the engine from different tanks (typically left and right wing tanks).
Should you team the FSM up with our DX1 display, the cockpit crew will get a dedicated page with a graphical representation of the fuel layout as well as current situation, as examples of are shown below.