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dee0861
Samba Member
Joined: January 23, 2023
Posts: 17
Location: UK
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 Posted: Sat Oct 04, 2025 6:46 am Post subject: VDO Fuel gauge |
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I have a 1956 Oval, its fitted with a VDO fuel gauge.
The wires go to earth and also to a connection on the outside of the fuel filler neck.
Its obvious that there is some kind of fuel sender inside the tank, but I have no idea how it works.
I was considering removing from the tank to have a look at the workings.
The gauge does not read well at all, but it looks great on the dash.
Does anyone have any knowledge of these gauges and sender units and can help with more information.
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56Cabrio
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Joined: May 22, 2008
Posts: 2078
Location: San Fernando Valley, CA
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56Cabrio
Samba Member
Joined: May 22, 2008
Posts: 2078
Location: San Fernando Valley, CA
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dee0861
Samba Member
Joined: January 23, 2023
Posts: 17
Location: UK
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| Posted: Sun Oct 05, 2025 5:14 am Post subject: Re: VDO Fuel gauge |
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Great help guy's and fab pictures.
Just need to work if its the gauge not reading due to connectivity issues, or if I need to delve deeper and remove the unit.
First thing is to fill with fuel and see if the float, float's  |
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quik55
Samba Member
Joined: June 27, 2015
Posts: 18
Location: Los Angeles
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| Posted: Sun Oct 05, 2025 7:56 am Post subject: Re: VDO Fuel gauge |
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There not a lot of information on this type of fuel gauge. After a lot of research I finally found a nos instruction. Hope this helps.
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Bub
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Joined: June 10, 2004
Posts: 1332
Location: Central Washington
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| Posted: Sun Oct 05, 2025 9:21 am Post subject: Re: VDO Fuel gauge |
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Take the wire attached to the sender and ground it to metal, if your gauge goes to FULL then it's not totally dead at least.
At that point you have to investigate the sender status.
FWIW one of these senders WILL work with that gauge (6v or 12V doesn't matter to the sender)- I just can't remember which one.
And it CAN be mounted in the filler neck like the original with a little bit of messing around with the bracket.
https://a.co/d/4OAGDIS
https://a.co/d/b7HGS0i
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dee0861
Samba Member
Joined: January 23, 2023
Posts: 17
Location: UK
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| Posted: Sun Oct 05, 2025 10:52 am Post subject: Re: VDO Fuel gauge |
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I presume that's the live wire to the sender that you ground, with the Ignition on ?
Sorry Im a it of a idiot with electrical stuff. |
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Bub
Samba Member
Joined: June 10, 2004
Posts: 1332
Location: Central Washington
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| Posted: Sun Oct 05, 2025 10:59 am Post subject: Re: VDO Fuel gauge |
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| dee0861 wrote: |
I presume that's the live wire to the sender that you ground, with the Ignition on ?
Sorry Im a it of an idiot with electrical stuff. |
No, there is no V+ to the sender. The sender goes directly to ground- and the resistance is varied by the position of the float.
There’s no risk in grounding the sender, when it’s at Full it’s running that circuit nearly directly to ground with no resistance.
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| Had a girlfriend once who shall we say, nearly arrived at the mere sight of a semaphore in action- easy to please she was... |
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dee0861
Samba Member
Joined: January 23, 2023
Posts: 17
Location: UK
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| Posted: Sun Oct 05, 2025 12:00 pm Post subject: Re: VDO Fuel gauge |
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Bub, thanks, but you are talking in language I don't understand fully.
I I take the wire attached to the outside of the filler cap and ground it will the fuel gauge read full if its working.
Then I can look at the sender as the source of the problem.
I did say, electrical is not my bag, but willing to learn. |
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quik55
Samba Member
Joined: June 27, 2015
Posts: 18
Location: Los Angeles
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| Posted: Sun Oct 05, 2025 12:31 pm Post subject: Re: VDO Fuel gauge |
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Bub
Samba Member
Joined: June 10, 2004
Posts: 1332
Location: Central Washington
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| Posted: Sun Oct 05, 2025 12:58 pm Post subject: Re: VDO Fuel gauge |
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| dee0861 wrote: |
Bub, thanks, but you are talking in language I don't understand fully.
I I take the wire attached to the outside of the filler cap and ground it will the fuel gauge read full if its working.
Then I can look at the sender as the source of the problem.
I did say, electrical is not my bag, but willing to learn. |
If you have 2 wires going to your sending unit one of them will be a wire that goes from the sender to metal, and grounds the sending unit.
The other wire will go from the sending unit to the fuel gauge; you can leave this wire connected, but just take a small wire and ground it to chassis/metal.
Some sending units have only one wire, and they ground through the fixing screw/bolt to the fuel tank, which is itself grounded since it is bolted to the body. *If you only have one wire, jump a ground wire to this one. The is no live 'voltage' connected to the sending unit- at least there should NOT be, that would pretty wrong.
You can also test it by grounding the signal at the back of the gauge: On the back of your gauge you have usually 3 connections.
6V+, wire to the bulb from headlight switch, and the other wire goes to the sender. You *might* have one extra wire that grounds the gauge housing, but they typically ground through the housing nand dash.
DONT ground the 6V connection, but DO ground the other one that might be labeled 'G' ?, This is the wire that when grounded and makes the needle go to FULL.
One way these quit working is the sending unit may have lost a good ground connection: take a length of wire and attach it to the metal part of the sending unit where it's bolted to the filler neck, and ground the other end. If this makes your gauge work a little then grounding the sending unit may be all you need to do.
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| Had a girlfriend once who shall we say, nearly arrived at the mere sight of a semaphore in action- easy to please she was... |
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dee0861
Samba Member
Joined: January 23, 2023
Posts: 17
Location: UK
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| Posted: Mon Oct 06, 2025 10:21 am Post subject: Re: VDO Fuel gauge |
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Thank you everyone who contributed to this post.
Brilliant information.
Gauge is good, managed to lift the sender up and got a good reading.
Then took the sender out of the tank, date stamped 5/56.
The float is cork, and not floating in the fuel.
On removal the cork was covered in a layer of reddish paint, which came off very quickly when I wiped it clean of fuel.
Just need to find a good float replacement, probably a more modern plastic one.
Thank you all. |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 26248
Location: Olympia Wash Rinse & Repeat
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| Posted: Mon Oct 06, 2025 11:26 am Post subject: Re: VDO Fuel gauge |
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| dee0861 wrote: |
Just need to find a good float replacement, probably a more modern plastic one.
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Might let the float dry out fully over a few weeks. Then coat with a fuel proof plastic coating.
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AlteWagen
Troll
Joined: February 23, 2007
Posts: 8730
Location: PNW
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56Cabrio
Samba Member
Joined: May 22, 2008
Posts: 2078
Location: San Fernando Valley, CA
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| Posted: Mon Oct 06, 2025 8:26 pm Post subject: Re: VDO Fuel gauge |
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| AlteWagen wrote: |
| 56Cabrio wrote: |
I have the same gauge in my vert,
I recently took it out the sending unit to clean my tank.
The 6-59 date on the sender tells me it was added years later.
Hope the pics help |
What date is stamped on the gauge itself? Might of had the sender replaced at a later date. |
Hard to read but i think the last number is a 9
The gauge also has a 31/1 like on the sending unit.
Im eventually going to weld up the hole and put my Dehne gas gauge there
as I don't like the placement on the dash and think the Dehne looks better between the speedo and speaker grill.
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1956 Rag Top owned since 1988
1956 Convertible owned since 2000
1963 Hard Top
RIP Dad 4/20/1951 - 2/4/2023 |
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dee0861
Samba Member
Joined: January 23, 2023
Posts: 17
Location: UK
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| Posted: Thu Oct 09, 2025 9:11 am Post subject: Re: VDO Fuel gauge |
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This is the sender unit stamped 5/56, so fitted about 4 months after the car was registered, 11/02/1956.
Replaced the cork float, using two demijohn corks, roughly the same size as the original ones.
Coated the cork to make sure its protected from ethanol degradation.
Gauge is now working correctly.
Happy days.
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