How to Change a Fuel Pump in Your Car

  • 2-4 hours
  • Intermediate
  • 50-200

Know how to change fuel pump in your car to avoid costly repairs at a mechanic shop. This part of your car pumps fuel from the tank to the carburetor or fuel injectors in the engine. It then converts that fuel into power for the engine through its injection into the cylinders. Some of the older engines used gravity to achieve this purpose, while the later mechanical pumps were located outside the fuel tank. Most modern engines have one electrically driven fuel pump located in the fuel tank. Some vehicles may have an additional fuel pump located close to the engine.

Starting Right

The lines from a fuel pump will always be under pressure, even when the engine is switched off. One of the first things to do before you replace the fuel pump is to relieve the pressure in the lines. See that the level of gas in the tank is small preferably less than an eighth of its capacity. Remove the fuse to the fuel pump from the fuse box. Start the car and run it till it stalls. Continue to do this till the car does not start.

The fuel pressure in the line is now close to zero. Switch off the ignition and raise the hood and disconnect the negative battery terminal. Replace the fuel pump fuse. Now open the cap of the fuel tank, to completely negate pressure in the fuel lines. Now locate the access plate to the fuel tank (normally in the trunk) and disconnect the wiring. You will find hoses attached to the access plate which you would need to detach. Carefully mark all hoses and wiring so that you are sure of what goes where. You may find that there is still some fuel which will spill out when you disconnect the hoses and you should be careful to clean up this with rags, so that a dangerous situation does not arise from spilled gas.

Removing the Old Fuel pump and Putting a New One

Now gently work out the entire assembly from the access plate hole. First remove the fuel level sender till you see the pump holder. Snap that holder open to release the fuel pump. The fuel pump will have a siphon bag that is beneath the pump holder. First remove the power harness on the fuel pump and then loosen the clip that holds the siphon bag. Now remove the clip and use it to connect the siphon bag to the new pump which you must have ready. It is essential that you are using a new fuel pump which is of the correct model and make as suggested in your owner’s manual.

Now reverse the activities. Put the power harness back on the new pump and put the entire assembly back into the tank. Now reassemble the tank access plate ensuring that the hoses are correctly positioned, and reattach the wiring. Use a new O ring on the cover plate even if you think the old one is OK. This assembly is rarely removed during the life time of a vehicle, and it is therefore better to be safe than sorry, as any small defect in the ring could cause problems due to air leakage.

Restarting Your Car

Reconnect your battery. Take this opportunity to attend to any problems with the leads of the battery and its cleaning. Once the battery is reconnected, switch on the ignition without starting the car. You should hear the pump go on for a second, which it does to build up pressure in the fuel lines. This is the time to check that your hoses and other connections which you had loosened are properly clamped and are not leaking. Now remember to put the gas cap back on the tank and start the engine and allow it to idle for a few minutes before taking your car out for a test drive.

You have successfully replaced the fuel pump in your vehicle. Enjoy the drive.