It may seem simple, but the gas tank located between the rear wheels of your CJ7 does more than just storing your fuel. It actually ensures that the gas you fill it with can be measured, vented, and fed to the engine. It also needs to survive a lot of potential damage and prevent sparks from starting as you fill it up. With all of these functions, it's essential that you take care of any problems that arise before they get any worse. Here are a few signs that you need to be aware about:
Jeep CJ7 fuel tanks are made out of steel, and like any other automotive part made out of metal, it can be susceptible to corrode in areas where moisture pools. Make it a point to inspect the interior of your tank, especially under the straps that hold it to your chassis. If you catch the signs of rust in time, you can remove the spots and then fill up any holes with sealing putty. However, if you let your tank corrode, you'll find that you'll be spending a lot on gasoline that just leaks away. You'll need to order up a replacement tank right away.
Like any vehicle made after 1970, your Jeep CJ7 gas tank has a charcoal canister that filters out pollutants from your fuel system. This canister can sometimes malfunction, and you'll know when this happens thanks to a rough idling experience. You'll need to figure out if the canister has a blockage or if it's got a vacuum leak. Afterwards, you'll know if you should clean out the debris that's blocking the vent or if you should pinch off the vacuum line to take care of the leak.
Rough idling can also be an indication of an extremely common problem with tanks: fuel contamination. You'll know that you need to clean out the gas tank when you also experience loss of power, stalling, and premature failures of your other fuel system components.
If you experience a sudden surge of vaporized gas hitting your face after you open your gas tank, you can be sure that you've got pressure building up inside. This can be due to movement, heat, or the evaporation of the gas itself. You'll need to reduce the pressure by cooling the tank down so that the gasoline will condense.