How to Replace a Fuel Sending Unit

Written by dan ferrell
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How to Replace a Fuel Sending Unit
Typical fuel pump and fuel sending unit assembly. (Photo courtesy of Mechanic at Wikipedia.org.)

The fuel sending unit on your vehicle has an arm with a floating device that extends down into the lower part of the fuel tank. The arm is connected to a variable resistor, which sends a signal to the fuel gauge on the instrument panel of your car. This lets you know the amount of fuel left in your car. Often, the variable resistor or a mechanical components of the sending unit will wear out, providing inaccurate to the fuel gauge.

Skill level:
Moderately Easy

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Things you need

  • Wrench
  • Hand siphon pump
  • Fuel container
  • Floor jack
  • 2 jack stands
  • Ratchet and socket
  • Ratchet extension
  • Drift punch
  • Hammer
  • Spanner wrench if necessary
  • New sending unit rubber seal

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Instructions

    Relieve the fuel system pressure

  1. 1

    Remove the fuel pump relay and start the engine until the engine stalls. To locate the fuel pump relay and learn the correct procedure to relieve the fuel system pressure, consult your vehicle service manual.

  2. 2

    Replace the fuel pump relay.

  3. 3

    Detach the ground battery cable using a wrench.

  4. 4

    Empty the fuel tank through the tank filler neck using a hand siphon pump and a fuel container.

    Remove the Fuel Sending Unit

  1. 1

    Raise the rear of your car using a floor jack and support it on 2 jack stands. Some vehicle models provide access to the fuel-sending unit through an access door located on the floor, underneath the rear seat. To find out if you have access to the sending unit through the floor, consult your vehicle service manual.

  2. 2

    Place the floor jack underneath the gas tank to support it.

  3. 3

    Remove the tank straps' mounting bolts using a ratchet, ratchet extension and socket.

  4. 4

    Lower the tank a few inches and disconnect the fuel lines and hoses. Press the lock tabs on the hose plastic connectors and detach the lines and hoses form the fuel-sending assembly fittings.

  5. 5

    Unplug the fuel pump electrical connector.

  6. 6

    Lower the fuel tank to the floor.

  7. 7

    Disconnect the fuel-sending unit from the tank by unscrewing the cam lock holding the sending unit assembly to the tank. Use a drift punch and hammer to turn the lock counterclockwise. Some sending unit assemblies come equipped with a retaining ring, which can be unscrewed with a spanner wrench.

  8. 8

    Lift the fuel sending unit assembly off the fuel tank and discard the rubber seal.

  9. 9

    Remove the fuel pump from the old fuel sending unit.

    Install the Fuel Sending Unit

  1. 1

    Install the fuel pump on the new fuel sending unit.

  2. 2

    Set the new fuel sending unit assembly on the fuel tank along with a new rubber seal. Make sure the sending unit's long arm points toward the rear of the fuel tank.

  3. 3

    Secure the sending unit assembly by turning the cam lock or retaining ring clockwise. Use the drift punch and hammer or spanner wrench, depending on your vehicle model.

  4. 4

    Raise the fuel tank a few inches using the floor jack and plug the fuel pump electrical connector.

  5. 5

    Attach the fuel lines and hoses to the fuel sending unit assembly.

  6. 6

    Raise the fuel tank in place and install the tank straps' mounting bolts.

  7. 7

    Lower the vehicle and refill the fuel tank.

  8. 8

    Attach the ground battery cable using a wrench.

  9. 9

    Start the engine and check for leaks.

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