It is important to look at the ground where you park your car routinely. If the Cobalt has a fuel leak, you can see it on the pavement-a rainbow will appear on top the gasoline. Gasoline is very combustible, so get the car to a mechanic as soon as possible.
Drain the fuel tank of gasoline in a receptacle. Make sure the container can hold a combustible liquid. Look for a drain cock-some fuel tanks have one.
Twist the drain cock to loosen the valve-this allows the gas to completely drain from the fuel tank.
Find where the three fuel lines connect to the fuel tank and remove them. There will be gasoline in the lines, so have a wide mouth container to catch the excess gasoline. You need to find the supply line, the fill tube line and the vent line.
Search for the clamps on the two metal straps that hold the fuel tank in place under the Cobalt. Place blocks under the fuel tank so when the straps loosen, the tank doesn't fall on you.
Turn the nuts at one end of the straps and let them drop the tank on their own. Gravity will work in your favor if you let it.
Push the new fuel tank onto the blocks and refasten the straps with new nuts. If the straps are rusty, you can replace them at the same time. Reverse the removal of the fuel tank.
Maintain safety at all times, but especially when you pour the gasoline into the new tank. Start your car and let it run for a few minutes before you take it onto the highway. Check to make sure the gas leak is resolved.
