Some areas of this tank are...
Some areas of this tank are completely rust-free, while other areas are heavily rusted. This is common when the plated lead barrier coating of Terne steel begins to deteriorate. The filler hole is considerably larger on this '77 tank to permit insertion of the rubber bladder.
The '75 Corvette model year...
The '75 Corvette model year introduced a gas tank with a reinforced rubber bladder to reduce the chance of gas leakage after collisions that damaged the tank. An added benefit is that as long as the bladder is in good shape, rust perforation of the tank won't cause a leak.
If your tank is original,...
If your tank is original, there may still be a buildsheet (tank sticker) glued to the top surface. That's another reason for removing the tank-to preserve the sheet, which lists the options the car was built with. Photograph the sticker before attempting to separate it from the tank. These scraps were all that was left of mine.
Tank Maintenance-Vacuum Water and Debris
Inevitably water and dirt get into a gas tank. Dirt that passes the fuel strainer can cause problems with everything downstream, from the fuel pump valves to the carburetor, and, ultimately, cause engine problems. The effect of water on these parts can be just as bad or worse. water is heavier than gas and settles into the lowest part of the reinforcing channels stamped into the tank, which can cause the tank to rust-through from the inside. Fortunately, it's fairly easy to remove any water and dirt from a gas tank of a '63 to '74 Corvette by using a length of hose and a small metal tube.
Attach about eight feet of...
Attach about eight feet of transparent 1/4-inch rubber hose to a 1/4-inch brake line that's 12 inches or longer. The clear hose makes it easy to see, and, therefore, not taste the gas when starting the siphon. The 1/4-inch diameter produces a convenient slow rate of flow.
Insert the tube into the tank...
Insert the tube into the tank and position it in the front of one of the recesses at its lowest point. A strong flashlight helps, but you can also feel when the tube slides down into the recessed areas.
Start the siphon to vacuum...
Start the siphon to vacuum the water and dirt from the tank. Tip: bump the car slightly to cause the gas to move; this helps to see the edges of the water puddles beneath the gasoline.
A few minutes of gas tank...
A few minutes of gas tank maintenance can prevent future problems by removing water and dirt visible at the bottom of the container. The siphoned gas can be salvaged by pouring as much of it as possible into a second, clean container. If no dirt or water was transferred to the second container, this gas can go back into the tank.