Car repair

Fuel Tank

Removal

Fuel should be drained from tank as completely as possible prior to tank removal.
Vehicles with fuel injected engines have reservoirs inside the fuel tank to maintain fuel near fuel pickup during vehicle cornering maneuvers and under low fuel operating conditions. These reservoirs could block siphon tubes or hoses from reaching bottom of fuel tank. This situation can be overcome with a few repeated attempts using different hose orientations.

Disconnect fuel hoses and tubes. On vehicles equipped with fuel injection,
Disconnect electrical hookup to fuel tank sender unit. On some vehicles, electrical connection is inaccessible on top of tank and no intermediate connection point is provided. In these cases, electrical connector must be disconnected from fuel sender with tank partially removed from vehicle.
Place a safety support under tank and remove bolts or nuts from one end of fuel tank straps. The straps are hinged at one end. Remove bolts from unhinged end and swing straps out of the way.
Partially remove tank and disconnect fuel lines and electrical connector from fuel gauge sender, if required.
Remove tank from vehicle.

So I guess you have a leak? A small rust hole is fairly certain the longer you own a tempo especially in northern climates. I've repaired a few by soldering the hole and scraping/cleaning the tank and underrcoating it.