Gas gauge quit working

[iowa51]

Drove my '51 Plymouth in a nearby town's Memorial Day parade. Left home for the parade, checked gas gauge and it was between 3/4 and full, driving along about 5 miles later and notice it read empty. I know 3/4 to full is correct as I filled it up before putting it away last winter and have only driven it a few times this spring. 

 

Drove it to my other garage (15 miles from my house) to switch out with another car before coming back home. Quick check feeling under dash and wire is hooked up to gauge. Pulled rubber mat up in trunk and wire is still attached to sender. New sending unit a few years ago and no problems until now. Will be a few weeks before car comes back to my home place, wondering what to check/fix as to why the gauge just up and quit working.

Edited May 29, 2018 by iowa51

[busycoupe]

The gas gauge in my car often sticks on empty.  If it stuck when I start the engine I tap on the glass on the gauge to free it.  It is apparently some kind of physical problem with the gauge needle.  Perhaps yours has the same problem.

[greg g]

Mine acted up a while back, checked everything electrically and it all checked out. Getting under the dash, I noticed that one of the defroster ducts had fallen off the diffuser.  The metal stiffening band running through the paper duct was providing a ground path for one of the gauge terminals, causing it to read empty when in contact.  This was a two wire 1946 gauge, your later one may not be effected the same way. But its an easy thing to check

[JerseyHarold]

Check to see that the fuel gauge sender wire isn't getting shorted-out by the round cover in the trunk over the gas tank.

[White Spyder]

If it is original it may be that the old cork has finally rotted off the float arm  This happened to mine and I made a new float with wine corks until I can find a plastic fuel safe one.

[iowa51]

19 minutes ago, White Spyder said:

If it is original it may be that the old cork has finally rotted off the float arm  This happened to mine and I made a new float with wine corks until I can find a plastic fuel safe one.

 

 

it was replaced about  2 years ago with a new one and a plastic(?) float. If the float had a hole I would suspect it would slowly drop to empty and not drop to empty in less than 5 or so minutes. Will need to do more checking when I get the car back home.

[insaneradio]

This past weekend  I repaired mine.  Mine had a cork float.  They were originally coated with shellac to fuel proof the cork.  This was fine untill the introduction of alcohol in gasoline.  Alcohol breaks down shellac.  Threw me for a loop at first.  I removed and tested in water, It floated well.  However, when watching when I installed into tank I noticed the cork float sank!  It floated in water however not in gasoline.  I guess the differences in the specific gravity of gas to water made a difference.

 

Luckily I has a spare cork float on another bad sending unit.  I swapped cork float.    I then coated with butyrate dope found at hobby shop.  So car so good!

Edited May 31, 2018 by insaneradio