36 Ford Gas Gauge

[mtmodela]

I need some help. My gas gauge in my 36 Cabriolet doesn't always work. What might be the problem? I am thinking it is a grounding problem not sure. If it is, how should I ground the gas tank? Thanks Ford Barn

[19Fordy]

The gas tank should ground itself where it's bolted to the frame.
However, you could also run a separate ground wire from one of the screws ( that attaches the gas tank sending unit to the tank) to the frame. I did that as I have a polyethylene tank.
Have you removed the gas tank sending unit to see it's condition?

[mtmodela]

I just bought the car and noticed the gauge reads and then stops reading the fuel level. My thinking is that it is the ground and I haven't removed the tank as it is the original tank and the car was restored a few years ago. Is it hard to take the tank out to check? I mainly work on Model A Fords and haven't tried to remove this kind of tank before?

[19Fordy]

You don't need to remove the tank to remove the gas tank sending unit. Under the trunk floor mat there should be a little sheet metal cover that you remove to get access to the sending unit. Look thru this thread and you will see. Folks with 36 Fords can probably provide more help. Flip ignition switch to OFF when working with the wiring.
https://www.fordbarn.com/forum/showthread.php?t=91066

On my 40 I did the following to check if the gas tank sending unit was providing accurate readings to the gauge.

1. Shut OFF ignition switch.

2. Unscrew and remove gas tank sending unit. Take a photo of how it is wired before you remove it.

3. Place a piece of cardboard on your trunk floor and place the gas tank sending unit
on the cardboard making sure that no part of the sending unit contacts the metal floor.

4. Get a wire with and alligator clip on each end. Clip one end of that wire to the "hot" wire that comes from the dash gauge and wrap that connection with electrical tape to prevent it from making any contact with any metal. Attach the other end to the little screw on the top of the sending unit.

5. Use another wire with an alligator clip on each end and attach one end of that wire to one of the screw holes in the perimeter of the gas tank sending unit. Make sure that metal is clean. Now, clip the other end of that same wire to a good ground such as the trunk latch on the floor of the trunk. Your operating circuit is now complete.

6. Making sure that your "connections" are not touching any other metal or each other.
flip ignition switch to ON and manually move the gas tank sending unit float thru its range of motion a litttle at a time,checking the fuel gauge reading. Your gauge should register readings.

7. Flip OFF your ignition switch BEFORE you remove any of the alligator clipped wires and BEFORE you reinstall your gas tank sending unit.

Doing the above will let you know if your gas tank sending unit is working properly. If it is not, then you may need a new float or some internal adjustments. Contact Fordbarners who have encountered similar problems using the SEARCH function.

Sorry for the long, wordy discourse but I wanted to as clear as possible. If I have said anything incorrectly, I hope other Fordbarners will correct me. Good luck.

[terry]

I couldn't have explained it better! Save some time, though, and just check for a loose connection at the gauge itself before checking the sending unit. It may be a little tight under the dash but you don't need to remove the gauge to do this. Terry

[19Fordy]

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Thanks Terry. Your idea is a "must do" first.

[mtmodela]

Thanks, That should work.

[mtmodela]

Thanks, I will try that first.

[51woodie]

I did pretty much all of what 19fordy said when I was trouble shooting my sender, but I disconnected the power to the coil and taped over the connector, so I wouldn't do any harm leaving power on the ignition on while testing.

[JSeery]

Good idea!

[mtmodela]

Thanks to everyone on your comments. I now know what I need to do. Very informative.