Fuel gauge calibration

[harmony]

My Fuel gauge as always been a bit lazy and not too accurate, so I have been relying on my odometer for my fuel stops.  Fortunately I have my dash from my parts car so I pulled the fuel gauge out of it to have a good look at it. I had already removed the radio previously.  (I'll mention the radio later).  

I pulled the sender unit out of the gas tank and hooked everything up on the bench and did a test as the manual explains.  So my sender unit seems ok and so does my fuel gauge out of my parts car.  So it seems I need to have a look at my fuel gauge and possibly recalibrate it.

Has anyone pulled a fuel gauge out of a 48 Windsor before?

Please don't tell me to type my question into google.  ?  I'm looking for good old fashioned stimulating conversation about this.

 

I've pulled the ignition switch out and I took off a 3/8" nut from a protected stud that had a wire coming from the ignition switch and another wire heading off somewhere.  Once all that was out of the way, it looks like one of the 2 fastening screws ( slot) that hold the fuel gauge in place is behind the radio.  So it looks like I have to remove the radio to get the fuel gauge out.  

 

The only other option I see is to remove the 4 nuts holding the whole instrument panel in place and try to get t the fuel gauge from the front ???

The first image shows the back side of the fuel gauge.  Behind the stud/nut that's holding the black with yellow tracer in place is some of that protective black cardboard.  Across the top of the image you'll see a slot screw.  That's one of the two slot screws that hold the fuel gauge in place.  

The next image shows that protective cardboard folded back and you can just barely see the second slot screw.  But you can't get a screwdriver on it unless the radio is removed.

Conversation is welcome, as opposed to being told to type something into google for my answer.  haha!

Edited April 27, 2022 by harmony

[harmony]

Just now, harmony said:

My Fuel gauge as always been a bit lazy and not too accurate, so I have been relying on my odometer for my fuel stops.  Fortunately I have my dash from my parts car so I pulled the fuel gauge out of it to have a good look at it. I had already removed the radio previously.  (I'll mention the radio later).  

I pulled the sender unit out of the gas tank and hooked everything up on the bench and did a test as the manual explains.  So my sender unit seems ok and so does my fuel gauge out of my parts car.  So it seems I need to have a look at my fuel gauge and possibly recalibrate it.

Has anyone pulled a fuel gauge out of a 48 Windsor before?

Please don't tell me to type my question into google.  ?  I'm looking for good old fashioned stimulating conversation about this.

 

I've pulled the ignition switch out and I took off a 3/8" nut from a protected stud that had a wire coming from the ignition switch and another wire heading off somewhere.  Once all that was out of the way, it looks like one of the 2 fastening screws ( slot) that hold the fuel gauge in place is behind the radio.  So it looks like I have to remove the radio to get the fuel gauge out.  

 

The only other option I see is to remove the 4 nuts holding the whole instrument panel in place and try to get t the fuel gauge from the front ???

The first image shows the back side of the fuel gauge.  Behind the stud/nut that's holding the black with yellow tracer in place is some of that protective black cardboard.  Across the top of the image you'll see a slot screw.  That's one of the two slot screws that hold the fuel gauge in place.  

The next image shows that protective cardboard folded back and you can just barely see the second slot screw.  But you can't get a screwdriver on it unless the radio is removed.

Conversation is welcome, as opposed to type something into google for your answer.  haha!

woops, the first image didn't load.  Lets try again.

[desoto1939]

I noticed that you have a condenser attached to the back of the fuel gage.  On my 1939 Desoto there is a brass hole at the top of my gage also for a condenser to help with the static for my radio but I do not have the condenser  If you take out you fuel gage can you take some pictures of the condenser and the wire and how it is inserted into the brass hole and how the condenser is attached to the back of the fuel gage.

 

Rich Hartung

Desoto1939@aol.com

 

cell 484-431-8157

[harmony]

29 minutes ago, desoto1939 said:

I noticed that you have a condenser attached to the back of the fuel gage.  On my 1939 Desoto there is a brass hole at the top of my gage also for a condenser to help with the static for my radio but I do not have the condenser  If you take out you fuel gage can you take some pictures of the condenser and the wire and how it is inserted into the brass hole and how the condenser is attached to the back of the fuel gage.

 

Rich Hartung

Desoto1939@aol.com

 

cell 484-431-8157

Yes, I will.  I was curious about that as well.  Because my parts car didn't have that condenser.  I'm wondering where that wire is going?   My camera actually gives me a better view than my eyes.  I think maybe the band around the condenser has an eye on the end and it is under the stud that holds the black w/yellow tracer wire.  I thought for sure once I took that nut off and that wire, that the condenser would fall off as well.  Not only can I barely see up in there, I can't get anymore than one finger in there.  On the right side of the picture there is a bar, covered in a black sheath.  That supports the top of the dash to the bottom of the dash.  I think if I remove it tomorrow, I'll have more room to see and feel around.  I hate the thought of having to remove the radio, but I don't see any other choice.  

[harmony]

Just now, harmony said:

Yes, I will.  I was curious about that as well.  Because my parts car didn't have that condenser.  I'm wondering where that wire is going?   My camera actually gives me a better view than my eyes.  I think maybe the band around the condenser has an eye on the end and it is under the stud that holds the black w/yellow tracer wire.  I thought for sure once I took that nut off and that wire, that the condenser would fall off as well.  Not only can I barely see up in there, I can't get anymore than one finger in there.  On the right side of the picture there is a bar, covered in a black sheath.  That supports the top of the dash to the bottom of the dash.  I think if I remove it tomorrow, I'll have more room to see and feel around.  I hate the thought of having to remove the radio, but I don't see any other choice.  

Ohhhh, yes, after reading your post again, I do remember seeing a tiny hole in my parts car fuel gauge and wondering what it was all about.  But I don't remember seeing any kind of a set screw that might hold a wire in it.  It's a very tiny hole, so perhaps it has sharks teeth on the inside.  Like you can push a wire in but can't pull it out sort of thing.  Anyways I'll look closely at the parts car gauge tomorrow as well.

[harmony]

It's actually quite interesting how the fuel gauge works.  Everything is soo small and close together that I couldn't really get any good pictures that would tell the story.  The picture in the manual really doesn't show the working of the gauge very well.

Edited April 27, 2022 by harmony

[harmony]

Well everything went fairly smooth today recalibrating the fuel gauge.  In the end I did have to remove the radio to get the fuel gauge out but it was just a matter of removing a bolt off the mounting bracket at the back and taking off the nuts on the face behind the knobs.  

 

Once I got the fuel gauge out it is slightly different. I'm terrible at electrics but I'm thinking that maybe that gizmo is a resistor and not a condenser, because it has a wire coming off both ends. 

 

The power goes to the extra stud at the bottom in the picture.    

[harmony]

So the power goes to that stud in the above picture first.  You can see the head of that stud at the bottom of this picture marked A then the wire coils around that insulated board like a coil (B) and then goes to the centre post (C)

[harmony]

This picture shows the wire coming off the bottom, then it goes through the board to that stud (hot)

[harmony]

The top wire is soldered to a brass clip that is fastened to the board and then it is shaped into a point and then it goes into that tiny hole at the top of the fuel gauge assembly and that acts as the hinge so to say for the adjustable arms used to calibrate it.

[Sniper]

That cylinder thing is a condenser, more commonly known today as a capacitor.

 

That wore coiled around the board is what is known as a wire wound resistor.

[harmony]

AS for the calibration adjustment.  In this picture you can see the gap where the arrow points.  This is where it was when I took it the gauge out.  

[harmony]

This picture shows how much it took to make the appropriate adjustment.  Not much at all.  

[harmony]

The fuel gauge has been stopping once it got down to half full.  When I filled the tank it went all the way to full.  So I set up a bench test as per the manual.  I got a piece of wood doweling and put it in the tank and marked on it where the fuel sender would be.  Then on the bench that gave me a rough idea of where the bottom of the cork float would be when it was empty.  So I set the adjusting arm on the fuel gauge (G in the manual) so the tank is about 1/8" full when it reads empty now.  

But it's mostly guess work on the bench.  It will be interesting to see how close I got it once the gauge and sender are back in the car.  The only way you could get it accurate as a bench test is if you had a spare gas tank and cut the side out of it to get the float level exactly where you want it. 

 

I suppose I could suck all the gas out of the tank, once the fuel gauge is put back in and then put the sender in to see if I'm close.  But at that point I really don't want to pull everything out again to make a miniscule adjustment all over again.  It is really painful up under the dash all twisted up trying to fiddle with all the nuts and screws.  Going back in, I'll be fighting gravity getting the screws and nuts back on and tight.  I don't think I want to do it twice, or more.

 

It was pretty educational, and now I know exactly how the fuel gauge works and how to fine tune it. Oh btw I did run some cardboard through the points several times until I wasn't getting any black stuff on the cardboard.  Everything is nice and clean and I tested it several times and it had good reading each time for empty, 1/4, 1/2, 3/4, and full.  Assuming that I was holding the float level at what I thought was those positions. 

Edited April 28, 2022 by harmony