The gas tank on a 1990 Chevy Corsica is 15.6 gallons. A 1990 Chevy Corsica takes unleaded gas not premium.
For a 1991 Chevrolet Corsica : My Chilton's Auto Repair Manual shows : ( 15.6 U.S. gallons )
in the fuel tank
My 95 with the 3.1 V6 has a 15.2 gal tank. It should be in the owners manual under car specs
Inside the fuel tank.
It is in the fuel tank.. You should obtain a HAYNES manual for this job. NAPA stores.
take out the 2 bolts that hold it