Fuel gauge reading half-full when empty

[DavidAH]

1966 2 door saloon with gold speedo and fuel gauge.
The needle on the fuel gauge moves properly when ignition turned off/on, i.e. the gauge reads empty when ignition is off and when the ignition is turned on it moves to between half-way and full. It reads full when tank is full.
My problem is the fuel gauge always reads half-full when the tank is nearly empty….any ideas?

[svenedin]

I believe the fuel sender in the fuel tank works by the electrical resistance varying according to the position of the float arm in response to the fuel level. The first thing I would do is check all of the electrical connections. Ensure the connections are clean, bright (clean with emery paper and contact cleaner) and secure and go from there. Disconnect the battery before disturbing electrical connections near the fuel tank. Also check connections at the dashboard end. The fuel sender is in the top of the fuel tank and to access it you would need to remove the wooden boot shelves and the spare wheel.

I don’t have my reference books to hand but I thought by 1966 there is a voltage stabiliser that provides stabilised voltage to the fuel gauge but “gold Speedo” confuses me because I thought they were earlier


Stephen

[geoberni]

I don’t have my reference books to hand but I thought by 1966 there is a voltage stabiliser that provides stabilised voltage to the fuel gauge but “gold Speedo” confuses me because I thought they were earlier

Stephen

You're right, the Black Face Speedo was introduced in the Oct '64 update. So something been messed with.....

1966 2 door saloon with gold speedo and fuel gauge.
The needle on the fuel gauge moves properly when ignition turned off/on, i.e. the gauge reads empty when ignition is off and when the ignition is turned on it moves to between half-way and full. It reads full when tank is full.
My problem is the fuel gauge always reads half-full when the tank is nearly empty….any ideas?

Does your Speedo flick up to reading as soon as the Ign switched on, or does it rise (& fall) sedately?
Because a '66 car should be the latter Gauge system, but that wasn't on Gold Speedo cars...

Which sender top can you see on/at the fuel tank, Sender A, or Sender B...?

Fuel sender.JPG (40.02 KiB) Viewed 6891 times

[ManyMinors]

You have the wrong gauge fitted if your car is a 1966 model. A gold face gauge will not work correctly in conjunction with a 1966 tank unit. In the above picture, tank unit "A" is correct for a gold faced gauge (up to October 1964). Tank unit "B" is correct for the black faced gauge fitted from October 1964 onwards. As said above, the black faced gauge works with a voltage stabiliser which is what makes the needle rise and fall slowly and give a more accurate and consistent reading. It seems that your car has a mixture of parts?

[DavidAH]

Hi all, thanks very much for your comments.
I have a confession and apology ……..I submitted my initial post without checking the car, and after managing to wrestle the car from my daughter today I realised that it has a black face speedo and fuel gauge fitted, not the gold type!
Apologies for the confusion…..a “senior moment” I think!

[geoberni]

In that case carry out standard 'Fuel Gauge' fault finding, as has been commented on here numerous times.

[engineer]

Does anyone know the correct resistance through each type of sender unit at high & low fuel levels ? My Series two has non original speedometer & fuel tank. It did seem to work until recently when I ran out of fuel with the gauge still indicating half full. A good job that I keep a can in the boot.

[geoberni]

Does anyone know the correct resistance through each type of sender unit at high & low fuel levels ? My Series two has non original speedometer & fuel tank. It did seem to work until recently when I ran out of fuel with the gauge still indicating half full. A good job that I keep a can in the boot.

Have a read through these two documents, they're pretty good and I'm sure I've see those details there some where, probably even by type number:

https://www.triumphclub.co.nz/wp-conten ... _1_1v3.pdf
https://www.triumphclub.co.nz/wp-conten ... _2_2v0.pdf

[engineer]

Thank you. My car is a Series 2, which has now got a later Speedo with bimetallic gauge & voltage regulator. The fuel tank is a 6 1/2 gallon but the sender is the early type used with the gold gauge. The car is converted to negative earth. It the tank wasn't brim full, I'd take the sender out. Some puzzling to do , aided by your info.

[ManyMinors]

Thank you. My car is a Series 2, which has now got a later Speedo with bimetallic gauge & voltage regulator. The fuel tank is a 6 1/2 gallon but the sender is the early type used with the gold gauge. The car is converted to negative earth. It the tank wasn't brim full, I'd take the sender out. Some puzzling to do , aided by your info.

You always need a matching fuel gauge and sender unit. From what you say, it sounds as if you just need to fit the later sender if you already have the later gauge? I don't think it'll make any difference what polarity the car is wired if you have used the parts from an original later Minor. All standard Minors were positive earth to begin with and if you change the polarity you don't do anything with the gauge - assuming the parts used are standard.