Fuel Sending Unit

[50Dodge]

Since I’ve owned my 50 Coronet for a year my gas gauge hasn’t worked. Tonight, I checked and found that I am getting 6v to the gauge. I assume this means my sending unit it bad? If so, how do I replace it? I see in the trunk a locking ring, does this come off and sending unit comes out the top of tank? Thanks in advance. 

[DJ194950]

Having 6 v. to the gauge on one of the two terminals is correct.

It works with the other gauge terminal is connected to a variable ground- the level sender in the fuel tank.

Check to make sure that the level sender has a good ground by adding a jumper wire from the sender outside edge to the body and see if the gauge moves. If not remove the locking ring on the sender and remove it. Many are bad because of the front has drowned!? If appears OK then move the float through its range of motion with your jumper wire attached sender to body- does it change gauge reading?

 

DJ

[Plymouthy Adams]

first...don't assume you have a bad sender without first checking continuity of the wire and verifying your tank ground.....when these are proven, then go through your tests.....

[50Dodge]

How/where would I see if the tank is ground?

[Plymouthy Adams]

use of volt/ohm meter....if you do not have this....you really guessing with anything electrical on your vehicle...

[50Dodge]

Here is what I have found. I have found that my 6V hot wire going to my gas gauge has visible of being burnt and my gauge is also burnt at that female terminal. I have a new gauge, but now I am worried to clean up that wire and install again with the fear that I would burn up another gauge. What would cause this wire to get hot like this, and or where else should I check? Obviously I can trim back the exposed wire and reinstall another end, but not sure if I needed to check anything else.

 

 

[Young Ed]

You sure thats burnt and not just a crumbling ancient wire? 

[Dodgeb4ya]

Your wire is not burn't..it is old and frayed.

Typical of old cloth and rubber insulated automotive wire.

The female bullet connector looks to have old age corrosion. 

[JBNeal]

That cloth covered wire isn't sealed to the environment like modern insulated wire, so the conductor strands are prone to corrosion along the length of the wire, not just at its stripped ends.  The result is sky high impedance that wreaks havoc on 6V systems, not only on instrumentation but lighting and the entire charging circuit.  The black residue present appears to be a result of corrosion, elevated impedance,  and intermittent electrical contact resulting in low voltage arcing.  That original wiring harness may work for now, but has degraded in performance greatly since production and may be on the threshold of complete failure.  This is what happened to my '49 after being parked one wet winter; springtime preparation for getting back on the road found multiple locations of wiring failure, so that truck is parked until a new wiring harness is built...maybe next year

[Sniper]

I just rewired my 51 because  of issues like that and by prior owners/mechanics hackery.  Like this example of the kwality work I found.

[DonaldSmith]

There was a rubber insulation over the wires back then, but it needed the protection of the fabric covering.  Insulation has improved vastly since.   

[John Reddie]

What I would do in this case is to run a new wire and connectors in place of the damaged wire you now have and see if the fuel gauge works correctly. As was mentioned too, be sure you have nice clean grounds as well. Good luck to you.

John

[50Dodge]

I wanted to circle back and thank everyone for the assistance. Purchased a new sending unit, repaired the old section of wire and now have a perfect working system. Thanks again!