The fuel pump in the 2003 BMW Sedan 325i is located inside the fuel tank. As you press on the gas pedal, the pump pushes gas into the engine instead of pulling it. To remove the pump, you must remove the gas tank. Because you are dealing with gas and gas vapors, this task should only be attempted if you feel comfortable working around gas. Take precautions to ensure you are not working around open flames such as heater pilots and cigarettes.
Open the fuel door and remove the two bolts that secure the filler tube to the filler tube mount using a socket and ratchet.
Place a floor jack under the gas tank and raise the jack until it butts up against the bottom of the tank.
Remove the bolts that hold the tank straps in place using a socket and ratchet.
Lower the jack to lower the gas tank out of the vehicle. As you get the tank halfway down, disconnect the wiring harness from the bulkhead on the top of the tank. Lower the tank completely and fully out from under the BMW.
Place a brass rod at a 45-degree angle to the tab on the bulkhead. Strike the brass rod with a rubber mallet and turn the bulkhead counterclockwise. Do not use a metal rod, as it could cause sparking.
Bull the bulkhead free from the tank. The pump secures to the underside of the bulkhead.
Loosen the jam nut that holds the pump to the bulkhead using a wrench and remove the pump.
Thread the new pump onto the tube connected to the bulkhead and tighten it using the jam nut and a wrench.
Place the bulkhead back onto the tank and turn it clockwise to lock it in place. Use the brass rod and rubber mallet.
Slide the tank back under the BMW and lift it into place using the jack. As you get halfway up, reconnect the wiring harness to the bulkhead.
Secure the tank straps using the socket and ratchet.
Secure the filler tube to the filler tube bracket using the socket and ratchet.
