Replacing Your Mustang Gas Tank

Replacing the gas tank sounds like a pretty tough job. Actually it is one of the easier things you can do for your Mustang. The tank bolts are under the trunk mat. It comes out through the trunk. The concern with this job is getting the gas out of the existing tank, safely, and disposing of the old tank.

Here are the steps:

  1. Purchase a new tank. They are available from numerous vendors. Your choices are one with a drain plug or one without. Your Mustang gas tank came with a drain plug.
  2. Empty the gasoline from the old tank. Now there are a couple of things you can do. Do this when the tank is almost empty and this step is minor. My GT 350 had about 1/4 tank of gas and was leaking through some rust cracks on the floor of it. I had to play the hand dealt to me. I tried to siphon it out of the gas cap. I bought on of those special hoses that has a self primer on it. Trash. Waste of my money. I ended up doing it from under the car. Get a container that can hold the gas. Crawl under the back of the car and remove the gas line from the tank. At the end of the line is a rubber piece that connects the metal gas line and the gas tank, carefully remove the rubber hose at the gas line end. Keep in mind there is gasoline in the tank and when you separate the rubber from the line gasoline will start running out. Drain it into your container or bucket. If you used a clean bucket, you can reuse the gasoline. If you didn't and the gas is contaminated, you have to dispose of the gasoline properly.
  3. Open the trunk and remove the trunk mat. Remove the bolts holding the tank in place. Carefully lift the tank out of the trunk. Check the seal around the tank opening. Replace if necessary.
  4. Reverse the process to install the new tank. Tighten the bolts. attach the new rubber hose you replaced the old one with to the tank. Then do the same with the gas line.
  5. Put fresh gas in the tank.
  6. You will have air in the line. When you start your car, the fuel pump will pull the air out. It will take a few minutes of turning over for the air to be replaced with gasoline. (This applies to carbureted cars only. Fuel injected cars have some different concerns.)
  7. If it doesn't start:
    Moving your old gas line can cause weaknesses in it to worsen. The metal gas line must have integrity the length of it so it does not suck in air. Might be a good time to replace the gas lines. Better safe than sorry.
    Moving the gas line could cause stuff that was lodged in it to move further and plug the line, or the filter. You do have a in-line gasoline  filter, right? If you don't, put one on before you change your gas tank, just in case. Don't want stuff to enter the carb.
  8. My GT 350 started right up with the new tank and some fresh gasoline
  9. Properly dispose of your old gas tank. BEWARE, gasoline fumes are HIGHLY flammable. Your old tank could very well contain fumes. An old gas tank is probably toxic waste as defined by your state laws and so would be the gasoline you removed into an old container. It is very likely it would be against the law to dump it anyplace other than your local toxic waste location. Be safe and be legal.