1957 Gas Gauge won't move past empty

C
Joined
Sep 5, 2014
Thunderbird Year
1957
No good news all around. I bought a new instrument voltage regulator. Same result, the gauge moved slightly from pegged out to the left of empty to empty. I then ran a new wire directly from the gas gauge to the sending unit. Same as above, a slight move from pegged to empty. I then took the sending unit out of the tank and manually moved the float arm to full. The gas gauge then goes to about 5/8 full (not going all the way to full is another issue but not the primary concern). All of the above is the same as before I started replacing any parts (except for the gas gauge going to 5/8, it originally went to 3/4 when I manually moved the float arm to full but that was with another sending unit).

Regarding the voltage regulator, the one available only has one screw hole to hold it down, while the original has two screw holes. The one hole version is much easier to install because you cannot even see the second screw to remove the original, let alone trying to get the second screw back in.
 
S

sre

Active Member
Joined
Jan 9, 2020
Thunderbird Year
1957
Did you run a ground wire from the gauge to a GOOD ground. Definitely the new one is easier to install. When you manually move the float do you have a good ground?? Off hand I don't know the ohm value the sending unit should be, maybe someone will chime in with the numbers or one of the restoration shops would know. A new one may not be correct.
 
F
Joined
Aug 17, 2019
Thunderbird Year
1962
No good news all around. I bought a new instrument voltage regulator. Same result, the gauge moved slightly from pegged out to the left of empty to empty. I then ran a new wire directly from the gas gauge to the sending unit. Same as above, a slight move from pegged to empty. I then took the sending unit out of the tank and manually moved the float arm to full. The gas gauge then goes to about 5/8 full (not going all the way to full is another issue but not the primary concern). All of the above is the same as before I started replacing any parts (except for the gas gauge going to 5/8, it originally went to 3/4 when I manually moved the float arm to full but that was with another sending unit).

Regarding the voltage regulator, the one available only has one screw hole to hold it down, while the original has two screw holes. The one hole version is much easier to install because you cannot even see the second screw to remove the original, let alone trying to get the second screw back in.
Not sure, but the stabilizer may be polarized. 12volt input and reduced to 8 volts. Reverse leads and check again.
 
S

sre

Active Member
Joined
Jan 9, 2020
Thunderbird Year
1957
The hookup wires only go on ONE WAY. The one wire is female the other male. DON'T switch them.
 
F
Joined
Aug 17, 2019
Thunderbird Year
1962
OK. That is good. It has been a while since I helped my friend fix his. We did have to bend the float arm to adjust the gauge reading. Can you make sure you have a good ground on the gas tank to the frame? It is mounted with rubber strips between the tank and metal straps to the frame. Run a jumper wire from tank to the frame. If the gauge worked when you pulled it and ran a separate wire from the sending unit to the gauge and it read 5/8. With a solid ground from the sending unit to the frame. It should read full. I think you are not getting a good ground. Frustrating, but keep up the faith.
 
C
Joined
Sep 5, 2014
Thunderbird Year
1957
I spent yesterday going through every response I received on the forum and even if I had tried the suggestion I tried it again. I grounded everything. I tried a new sending unit and instrument voltage regulator. I ran another power wire. I had exhausted every idea and nothing would get the gas gauge off of empty with the tank about half full.

As the gauge would register (up to 5/8 of a tank), with the sending unit outside the tank and empty when installed in the tank, many of the suggestions and especially the grounding ideas all seemed plausible. With nothing left to try and having a second sending unit so I could damage one and still have another, I thought I would try not only bending the float arm but also bending the “full” stop on the sending unit out of the way so the float arm was not so inhibited. I did that and outside the tank the gauge went to full. I then tried it in the tank and it also went to full. I made a few adjustments to the bend in the float arm and I believe the gauge now reads accurately.

So thank you to all that offered suggestions. Unfortunately, it boiled down to two separate sending units that were horribly inaccurate. Thank again!
 
F
Joined
Aug 17, 2019
Thunderbird Year
1962
I spent yesterday going through every response I received on the forum and even if I had tried the suggestion I tried it again. I grounded everything. I tried a new sending unit and instrument voltage regulator. I ran another power wire. I had exhausted every idea and nothing would get the gas gauge off of empty with the tank about half full.

As the gauge would register (up to 5/8 of a tank), with the sending unit outside the tank and empty when installed in the tank, many of the suggestions and especially the grounding ideas all seemed plausible. With nothing left to try and having a second sending unit so I could damage one and still have another, I thought I would try not only bending the float arm but also bending the “full” stop on the sending unit out of the way so the float arm was not so inhibited. I did that and outside the tank the gauge went to full. I then tried it in the tank and it also went to full. I made a few adjustments to the bend in the float arm and I believe the gauge now reads accurately.

So thank you to all that offered suggestions. Unfortunately, it boiled down to two separate sending units that were horribly inaccurate. Thank again!
Great!! Perseverance always come thru.
 
D

Dennis Williams

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Joined
Nov 22, 2022
Thunderbird Year
1957
With the ignition on, the gas gauge only slightly moves from pegged on the empty end to about the empty mark. The gauge needle moves about 1/8". There is about 1/2 tank of gas in the gas tank. I checked the gauge by grounding the wire that goes to the sending unit in the tank. The gauge goes immediately to full, so I have read the gas gauge is not the issue. I took the sending unit out of the tank and grounded the unit while still plugged to the wire to the unit. I could manually move the float arm and get an empty reading on the gas gauge at the empty position of the sending unit and about 7/8 full at the full position. I reinstalled the sending unit and again, the gauge just moved from pegged to empty. I then taped the sending unit arm in the full position. I reinstalled it and the gauge shows about 7/8 full. So, the sending unit is grounded okay but it appears the float will not move to register the gas level. I then checked to see if the float would actually float. I put it in a bucket of water and the arm moves as the float floats. As the sending unit did not seem to work properly, I took it apart to see if there was some internal adjustments. Yes and no, but either way, I put it back together and it doesn't really work anymore.

I then bought another sending unit hoping that this would solve the problem. Pretty much the same as above as the gas gauge only slightly moves when the unit is installed. The only difference from the first sending unit is that I have the new unit out of the tank and manually move the float arm to the full position, it will only read about half full. I have read bending the float arm may help but I have not tried that yet as there is no use bending the arm if the gauge will not register with the sending unit installed.

My only thought is to completely fill the gas tank and see what, if anything, happens. It seems futile as there is certainly a fair amount of gas in the tank. Any other suggestions?
That's a tricky one. Possibly the voltage stabilizer at the gauges. I would not bend tank sender under any circumstances. Floats can sink., checked that. Maybe the wire.
 
Ward 57

Ward 57

Active Member
Joined
Aug 14, 2019
Thunderbird Year
1957
That's a tricky one. Possibly the voltage stabilizer at the gauges. I would not bend tank sender under any circumstances. Floats can sink., checked that. Maybe the wire.
What? A new sender float sinking? Maybe an original by being rotted but the aftermarket sensors are known to need the float arm to be adjusted. Calbears had it right. The crud being produced is almost never right unless produced here. He adjusted the arm and the arm stops and made it work. I give him great Kudus by going outside the box and questioning the engineering of the replacements and making corrections. Great advice for others and thank heavens mine still works well but did discover a wonky sender seal when I filled my tank for the first time in years but that is another story which I have documented before.
 
Rogvh

Rogvh

Active Member
Joined
Feb 14, 2014
Thunderbird Year
1957
Am curious what the gauge reading will be at actual empty. On two different of my cars with repro senders, they were not accurate on both ends of the gauge. I bent the arms so I had two gallons at the empty reading on the gauge while the other end of the gauge was way off but at least I wouldn't run out of gas. To my knowledge, all repro sending units are linear which is the cause of the problem, as opposed to the OEM being variable resistors. Attached are pics showing the yellow linear repro and the variable original. These are other models of Fords but the concept is the same. FWIW, repro CVR's have had a lot of problems whereby many think using a good/working used original is best.
 

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Ward 57

Ward 57

Active Member
Joined
Aug 14, 2019
Thunderbird Year
1957
Am curious what the gauge reading will be at actual empty. On two different of my cars with repro senders, they were not accurate on both ends of the gauge. I bent the arms so I had two gallons at the empty reading on the gauge while the other end of the gauge was way off but at least I wouldn't run out of gas. To my knowledge, all repro sending units are linear which is the cause of the problem, as opposed to the OEM being variable resistors. Attached are pics showing the yellow linear repro and the variable original. These are other models of Fords but the concept is the same. FWIW, repro CVR's have had a lot of problems whereby many think using a good/working used original is best.
Thanks. I'm pretty knowledgeable with OHM's law with low voltage DC circuits but have never heard of linear resistors. More suitable to digital circuits I assume?
 
rspon
Joined
Jan 27, 2023
Thunderbird Year
1956
With the ignition on, the gas gauge only slightly moves from pegged on the empty end to about the empty mark. The gauge needle moves about 1/8". There is about 1/2 tank of gas in the gas tank. I checked the gauge by grounding the wire that goes to the sending unit in the tank. The gauge goes immediately to full, so I have read the gas gauge is not the issue. I took the sending unit out of the tank and grounded the unit while still plugged to the wire to the unit. I could manually move the float arm and get an empty reading on the gas gauge at the empty position of the sending unit and about 7/8 full at the full position. I reinstalled the sending unit and again, the gauge just moved from pegged to empty. I then taped the sending unit arm in the full position. I reinstalled it and the gauge shows about 7/8 full. So, the sending unit is grounded okay but it appears the float will not move to register the gas level. I then checked to see if the float would actually float. I put it in a bucket of water and the arm moves as the float floats. As the sending unit did not seem to work properly, I took it apart to see if there was some internal adjustments. Yes and no, but either way, I put it back together and it doesn't really work anymore.

I then bought another sending unit hoping that this would solve the problem. Pretty much the same as above as the gas gauge only slightly moves when the unit is installed. The only difference from the first sending unit is that I have the new unit out of the tank and manually move the float arm to the full position, it will only read about half full. I have read bending the float arm may help but I have not tried that yet as there is no use bending the arm if the gauge will not register with the sending unit installed.

My only thought is to completely fill the gas tank and see what, if anything, happens. It seems futile as there is certainly a fair amount of gas in the tank. Any other suggestions?
I recently replaced my '56 sending unit and believe the one in the tank was the original. It only registered 3/4th even though the tank was full. The new unit came from C&G Ford Parts with instructions as to how to cut the float arm to length based on the depth of the tank. As part of this process, the arm required a 90* bend to insert into the arm that controls the resistance. My bend wasn't good enough to allow the assembled float to travel freely, so out it came and I corrected that issue. Now I'm driving around with a full tank and a full reading on my gas gauge, waiting for it to register less than full and hoping for that result!!
 
C
Joined
Sep 5, 2014
Thunderbird Year
1957
I recently replaced my '56 sending unit and believe the one in the tank was the original. It only registered 3/4th even though the tank was full. The new unit came from C&G Ford Parts with instructions as to how to cut the float arm to length based on the depth of the tank. As part of this process, the arm required a 90* bend to insert into the arm that controls the resistance. My bend wasn't good enough to allow the assembled float to travel freely, so out it came and I corrected that issue. Now I'm driving around with a full tank and a full reading on my gas gauge, waiting for it to register less than full and hoping for that result!!
Good luck and I hope it works for you. So far mine is working fine. I started with 3/4 of a tank and after some driving it reads about 1/2 full. The proof will be when it is close to empty as to what the reading is. It may take another tweak or two. I’m glad someone decided to give directions to make these things work.
 
rspon
Joined
Jan 27, 2023
Thunderbird Year
1956
Good luck and I hope it works for you. So far mine is working fine. I started with 3/4 of a tank and after some driving it reads about 1/2 full. The proof will be when it is close to empty as to what the reading is. It may take another tweak or two. I’m glad someone decided to give directions to make these things work.
I'm currently waiting for my fuel pump to come back from rebuilding, so no driving around. But, I did put a wooden yard stick down the filler pipe and found my tank is full. So "old farmer" method of checking fuel level is giving me some encouragement that the sending unit is working!! We'll see!!:rolleyes:
 
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