Gas Gauge

[COOL TOM]

WHAT MAKES THE GAS GAUGE WORK ON AN 82XJ11. WITH A FULL TANK OF GAS WHEN DRIVING DOWN THE ROAD THE WARNING LIGHT WILL FLASH, THEN WILL GO OUT AND SHOW FULL. WILL DO THIS ON AND OFF ALL THE TIME. HOW DO I GO ABOUT FIXING IT? ALSO TACK WORKS BUT IS SLOW, IT HOLDS STEADY GOING DOWN THE ROAD ABOUT 3500 AT 55 MPH BUT AROUND TOWN IT IS LUCKY TO GO OVER 3000.