Your solution to unusual activity with your gas gauge or repeatedly running out of gas on a regular basis may be a faulty fuel tank sending unit, or fuel sender.  In most cars, this really isn’t as big an auto repair as it may sound.  Start with your auto manual.  If the fuel tank sending unit is positioned beneath the back seat as many are, you are ready to get to work!  If it is under the carpet in your trunk, you are okay there too.

The Basics: Tools you will need

You always want to gather your supplies before starting on any auto repair or project.  Gather your screwdrivers (both Phillips and flat head), a hammer, some open end wrenches, and your new fuel tank sending unit.

Stop! Safety Warning! Read this section carefully!

You must start by disconnecting the negative battery cable.  This ensures no electrical sparks can be created.  You will be performing an auto repair to your extremely flammable gas tank.

To disconnect the negative battery cable, place one wrench on the outside nut.  If needed, put a second wrench on the other side.  You will turn the nut counterclockwise until you are about 1/16-inch or so from being off.  At this point, a small twist will hopefully pull it off easily.

Mechanic Tip: What to do with a stuck battery cable.

When necessary, you can use a flat head screwdriver to very gently pry the terminal open.  Insert the screwdriver into the gap above the bolt.  DO NOT pry the terminal upward off of the post!  Doing so could result in serious damages or injuries!  If doing this has not loosened it enough, you may need a little more strength in your twist.  Try using large pliers to add a little oomph.  This should do the trick.

Getting Started: Getting to the Fuel Tank Sending Unit

The fuel tank sending unit is found on the top part of your fuel tank.  It is accessible under the rear seat of the car.  In some cases you need to access your fuel tank by going under the carpet in the trunk.  There will be an access cover over the sending unit.  This is usually fixed in place by a few screws.  Start by lifting the back seat or carpet in the trunk.  Find the access cover.  Once you have it, remove the screws securing it.  You can now remove the cover and see the fuel tank sending unit.

Safely Removing a Fuel Tank Sending Unit

Remember: You are dealing with opening your gas tank for this auto repair.  You MUST exercise extreme caution and take care to make sure there are no sources nearby that could create a spark or flame of any kind.

The fuel tank sending unit is right on top with a wiring harness plugging into its top.  Simply unplug the wiring harness and move it to the side.  Your sending unit may be secured by screws or bolts.  You will need to remove them at this point if they are present.

Many fuel tank sending units work like the old gas caps that utilized a twist-lock.  You will see the notches around the outer ring.  Place the tip of a flat head screwdriver in a notch and lightly tap it in a counterclockwise direction.  This will rotate the sending unit loose.  The sending unit can now be removed in one piece.  Remove it carefully as it is attached to the long rod with a float going into the gas tank.

Installing the New Fuel Tank Sending Unit

This is the easy part.  Simply replace the old sending unit with the new one.  Now just follow these instructions in reverse to get all parts properly reinstalled and secured back in place.  Be sure that you remember to plug the wiring harness you detached from the old unit; otherwise the new unit will not be sending a thing.

As always, if you are not comfortable performing any auto repair, you should not do it.  We can schedule your auto repair or auto maintenance at our Columbia, SC auto repair shop.  Sanford’s Automotive Service is here for you!