for those so inclined. personally, my Van's stock float gauges have worked flawlessly for 1600 hrs. and I don't need to know, to the last drop, how much fuel is remaining 'cause I fill up after reaching 1/4 tank.
http://www.instructables.com/id/Paramotor-Fuel-Sensor-and-Gauge/
http://www.instructables.com/id/Paramotor-Fuel-Sensor-and-Gauge/