Things You'll Need
Replacement fuel sending unit
The fuel pump and fuel sending unit are one unit located in the fuel tank in your Nissan Xterra. Many vehicles have an access hole under the rear seat, but the Nissan Xterra doesn't, so it requires that you drop the fuel tank to replace the fuel sending unit. This isn't complicated, but may require a helper because the fuel tank is awkward to work with, especially if it is full of fuel.
Jack the Nissan Xterra and place it securely on jack stands.
Open the hood and remove the fuel pump relay. The relay will be located in the fuse box. When you remove the cover to the fuse box, look underneath it and you will see a diagram showing the location of the fuel pump relay.
Crank the engine over for approximately five seconds. Repeat two or three times to purge the fuel system of residual pressure. This ensures that fuel doesn't spray dangerously when you remove the fuel lines.
Disconnect the fuel filler from the fuel tank.
Disconnect the feed and return lines from the fuel tank. These are quick connectors that you can remove with your hands. Then disconnect three electrical connectors located at the fuel sending unit. Simply press down on the tab of the electrical connector and pull out.
Place a jack underneath the fuel tank and jack up the fuel tank, but do not put any pressure on it.
Remove the metal straps holding the fuel tank to the vehicle body, with a ratchet.
Lower the fuel tank to the ground.
Place the fuel tank in a suitable area to work.
Remove the screws or bolts holding the fuel sending unit to the fuel tank.
Remove the fuel sending unit and replace it with the new one. You may have to remove the old fuel pump and transfer it over to the new sending unit if yours didn't come with one.
Reinstall the fuel pump sending unit and tighten the screws with a screwdriver.
Place the fuel tank on the jack and jack the tank back in place. Place the straps around the tank and tighten the bolts to the Xterra's body.
Reconnect all the electrical connectors and the fuel lines to the new fuel sending unit.
Remove the jack stands and carefully lower the vehicle, with the jack.
Try to perform this operation when your vehicle is low on fuel, as dropping the tank will be much easier.
Wear safety glasses to protect your eyes.