For the fuel tank sending unit replacement install allow about 30 minutes. This is what it took me including taking a few pictures at each step. You may need extra time if you’re dealing with rust and corrosion around the unit/retaining ring.
Background #
All of my other gauges were working except the fuel gauge. I tested the gauge itself by briefly grounding the wire (Green and Black). In my case by removing the wire and putting it on the other connector on the sending unit (any ground source should work). The result was I saw that the needle went from empty to full pretty quickly. It’s probably best not to leave the gauge grounded for too long to avoid damaging it. So have someone ready to watch the gauge while you ground the wire.
The sending unit basically works like the float (ball cock) in a toilet. A faulty sending unit will probably be caused by one or two things. A float that has sprung a leak and is holding fuel and no longer floating. Or a problem with the electrics/resistance of the sending unit. Also it may simply be that the sending unit arm isn’t moving freely. Various suppliers have options for replacement floats and the complete unit. Moss Motors is one supplier example.
Test The New Sending Unit First #
To make sure your new unit is working, simply connect it to the sending unit wire, and a ground source. Then move the arm/float position. Have someone check the fuel gauge is moving. If all is well you can proceed.
Step By Step #
Step 1. #
You’ll need the tank to be virtually empty or minimally raise the car on the right side to keep your gas from leaking out through the sending unit hole. With 2 gallons or less in the tank I didn’t need to raise the car.
Step 2. #
Remove the outer retaining ring by tapping on the tabs and rotating the ring anti clockwise. You’ll see how the retaining mechanism works once you get close to the unit. I used a screwdriver and a rubber mallet for this.
Step 3. #
Remove the sending unit from the tank. You’ll need to angle the float and arm as you do this to get the unit out of the tank.
Step 4. #
Remove the rubber ring that acts as a sealer for the sending unit. That’s one of the might as wells in this process, since I went for the complete sending unit replacement. I didn’t want to assume the float was the problem and then later have to order a sending unit. I also got a new sealing ring and retainer clip. The seal might be a little stuck, so carefully pry it off the fuel tank (especially if you choose to reuse it and if it is relatively new or still in good condition).
Step 5. #
Replace the rubber sealing ring and insert the new sending unit into the tank. Make sure the sending unit is the correct way up. It can be verified from the outside with the electrical connector spade pointing to the rear of the car. As you insert the sender the arm needs to be at it’s lowest point and be able to rise when petrol (gas) is added.
Step 6. #
You may need to jiggle the sending unit a little to get it to seat flush against the rubber seal. Take your time with this. If it’s not flush remove it and try again. Once it’s flush you can then use the retaining ring to hold it in place. Line up the raised tabs and then rotate clockwise to lock in position at the 3 locking points. Tap the securing ring with the screwdriver and hammer to make sure it’s really tight.
Step 7. #
Connect the green with black sending unit wire to the main spade on the sending unit. Don’t worry about ground – the ground is handled by the connection of the unit to the tank. You should now have a working sending unit. Add some gas and check the gauge again!
Here’s a bonus picture of the sending unit out of the tank. You probably cannot see that the float was almost half full of petrol (gas).
Other Materials #
I hope you find this article and pictures helpful if you need to do a Fuel Tank Sending Unit Replacement. Please check for other fuel related topics or head back to the main knowledge base page to search for other information and technical tips and how to write ups.
