If your gas tank is full but your engine isn't getting any gas, you may need to replace the fuel pump. However, first make sure the problem isn't a broken gas line, clogged filter or an electrical problem.

Warning: Use extreme caution when working around gasoline. Work in a well-ventilated area, and keep electrical equipment and cigarettes far away. Keep a fire extinguisher handy, and use safety goggles, gloves and approved gasoline containers [source: Bumbeck].

Here's how to replace the fuel pump in a gas tank for cars with a carburetor engine.

  1. Disconnect the ground cable (it's usually black) from the battery's negative (-) terminal.
  2. Examine the fuel line from the gas tank and replace it if it's cracked or leaky.
  3. Release the gas tank pressure according to the instructions in the car's service manual.
  4. Loosen the clamp connecting the fuel tank hose and the vapor return hose, if there is one, to the old fuel pump. Disconnect the hose(s) from the pump.
  5. Plug up the end of the hose you just disconnected with a dowel or bolt.
  6. Disconnect the fuel outlet line going to the carburetor by grasping the fuel pump fitting firmly with one wrench while unscrewing the nut with another wrench.
  7. Unscrew the two fastening bolts and discard the old fuel pump.
  8. Remove any remaining sealant from the mounting flange.
  9. Coat both sides of the new gasket with a sealer.
  10. Insert the fastening bolts in the new pump and then slide the gasket into place.
  11. Mount the new pump. Make sure that either its rocker arm sits against the eccentric gear on the engine, or its actuating pushrod is properly connected to the fuel pump and engine.
  12. Connect the fuel outlet line to the new pump. First disconnect the line from the carburetor. Then connect the other end to the pump, reconnecting the free end to the carburetor. Tighten the nut using two wrenches the same way as when you disconnected the fuel outlet line.
  13. Tighten the clamp securely on the fuel tank hose (and on the vapor return hose, if there is one).
  14. Attach the ground cable to the battery's negative terminal.
  15. Start the engine and check the pump for leaks [source: Cockerham].