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Fuel gauge reading half-full when empty
Posted: Mon Oct 16, 2023 10:45 am
by 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?
Re: Fuel gauge reading half-full when empty
Posted: Mon Oct 16, 2023 1:07 pm
by 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
Re: Fuel gauge reading half-full when empty
Posted: Mon Oct 16, 2023 2:03 pm
by geoberni
svenedin wrote: ↑Mon Oct 16, 2023 1:07 pm
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.....
DavidAH wrote: ↑Mon Oct 16, 2023 10:45 am
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 8148 times
Re: Fuel gauge reading half-full when empty
Posted: Tue Oct 17, 2023 12:42 pm
by 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?
Re: Fuel gauge reading half-full when empty
Posted: Wed Oct 18, 2023 5:34 pm
by 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!
Re: Fuel gauge reading half-full when empty
Posted: Wed Oct 18, 2023 9:09 pm
by geoberni
In that case carry out standard 'Fuel Gauge' fault finding, as has been commented on here numerous times.
Re: Fuel gauge reading half-full when empty
Posted: Sun Nov 26, 2023 9:02 pm
by 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.
Re: Fuel gauge reading half-full when empty
Posted: Sun Nov 26, 2023 9:12 pm
by geoberni
engineer wrote: ↑Sun Nov 26, 2023 9:02 pm
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
Re: Fuel gauge reading half-full when empty
Posted: Mon Nov 27, 2023 5:08 pm
by 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.
Re: Fuel gauge reading half-full when empty
Posted: Mon Nov 27, 2023 11:25 pm
by ManyMinors
engineer wrote: ↑Mon Nov 27, 2023 5:08 pm
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.
Re: Fuel gauge reading half-full when empty
Posted: Thu May 02, 2024 8:43 pm
by Nickol
Rather than open a new thread I have opted to tag onto this one.
Electrical gremlins. Up to last week, the black fuel gauge on my 69 Traveller worked fine - when it had a power supply but we solved that. Then it started to misbehave. I did the standard check by earthing the sender wire , when the gauge read full. Then to be sure, I filled up with fuel but the gauge with the wire connected to the sender again read half full.
Obviously, there must be something wrong with the sender but as the tank is full I need to drive it a bit to get the level down before taking the sender out to check it. The sender is actually about 5 years old as the original bodge had the wrong one installed and gave inaccurate readings on the gauge. I think I replaced the gauge as well as I remember.
At the same time, my after market temperature gauge installed last year has been playing up as well. Same test, earth the sender wire, gauge reads boiling hot. Perhaps the sender is also kaputt???
Anyway today driving along after about 10 minutes glanced at the fuel gauge and it was reading correctly full; so too the temperature gauge reading at about 90°. Solved itself I thought but spoke too soon. After a a minute or two, both gauges went back to their faulty settings, fuel half full, temperature showing signs of life but indicatihg just over 50°.
They must be linked somehow to behave like that but the only common thing is the power supply but I do not remember how I connected the temperature gauge up last year. I do not think it went to the voltage regulator but that may need checking. It has been working fine for 18 months or so. It is such a pain to remove the glove boxes and steering wheel for access to the back of the speedo but before I do, will remove the fuel sender for inspection and before that, it occurs to me now, when the car is warm, earth the fuel sender to see if there is any effect on the temp gauge.
Jolly exciting - but unless I get this working there will be no trip to England in June in it.
Re: Fuel gauge reading half-full when empty
Posted: Thu May 02, 2024 10:23 pm
by Bill_qaz
Unless it's different on a 69 why do you have to remove glove box and steering wheel to take out speedo?
Don't you have the hole in the glove box liner so you can slack the screws and pull out the speedo.
Re: Fuel gauge reading half-full when empty
Posted: Fri May 03, 2024 8:48 am
by Nickol
Not without drilling a hole in the glove box liner, no.
Re: Fuel gauge reading half-full when empty
Posted: Fri May 03, 2024 8:50 am
by ManyMinors
I agree with Bill. You don't have to remove the glovebox liners - and the passenger side one is very easy anyway. Every Minor 1000 glovebox liner was made with a hole in it to access the speedo screw.
It does sound as if the voltage stabiliser (not the voltage regulator which is something completely different) may be the problem.
Re: Fuel gauge reading half-full when empty
Posted: Fri May 03, 2024 10:33 am
by Bill_qaz
Nickol wrote: ↑Fri May 03, 2024 8:48 am
Not without drilling a hole in the glove box liner, no.
So why not just drill holes like there should be?
- Screenshot_20240503-103020_Google.jpg (138.84 KiB) Viewed 566 times
Re: Fuel gauge reading half-full when empty
Posted: Fri May 03, 2024 4:06 pm
by Nickol
ManyMinors wrote: ↑Fri May 03, 2024 8:50 am
I agree with Bill. You don't have to remove the glovebox liners - and the passenger side one is very easy anyway. Every Minor 1000 glovebox liner was made with a hole in it to access the speedo screw.
It does sound as if the voltage stabiliser (not the voltage regulator which is something completely different) may be the problem.
Thank you for the correct Terminology to the voltage stabiliser. It is raining today so Morris is staying in the Garage until it gets dryer and can take it for a drive to reduce the petrol level in the tank.
The glovebox liners I have are replacements with no holes so holes can be drilled ....in the rigt place whereeve that is. I have found though, that replacing the speedo and aligning the holding screws is an art in itself.
Re: Fuel gauge reading half-full when empty
Posted: Fri May 03, 2024 4:32 pm
by Bill_qaz
You don't remove the screws, simply slacken as the speedo brackets are slotted. I have had mine out and back several time and I don't even retighten the screw , just have them loose enough to slide the speedo back in. We'll worth modifications to you liners.
Good luck with it
Re: Fuel gauge reading half-full when empty
Posted: Fri May 03, 2024 5:27 pm
by Nickol
Nickol wrote: ↑Fri May 03, 2024 4:06 pm
ManyMinors wrote: ↑Fri May 03, 2024 8:50 am
I agree with Bill. You don't have to remove the glovebox liners - and the passenger side one is very easy anyway. Every Minor 1000 glovebox liner was made with a hole in it to access the speedo screw.
It does sound as if the voltage stabiliser (not the voltage regulator which is something completely different) may be the problem.
Thank you for the correct Terminology to the voltage stabiliser. It is raining today so Morris is staying in the Garage until it gets dryer and can take it for a drive to reduce the petrol level in the tank.
The glovebox liners I have are replacements with no holes so holes can be drilled ....in the right place whereever that is? I have found though, that replacing the speedo and aligning the holding screws is an art in itself and being able to see where it goes in is a definite advantage.
Re: Fuel gauge reading half-full when empty
Posted: Sat May 04, 2024 7:52 pm
by Nickol
Solved the problem today although it took a while.
Firstly the Fuel gauge sender got removed and checked for its variable resistance which was ok - I do not quite understand how it is able to function when immersed in petrol but obviously it is designed that way.
Then the glove boxes and their frames came out in order to slide out the Speedo and sure enough I had connected both fuel gauge and temp gauge to the stabilised voltage tags. This gave erratic measurements for the voltage, (as it should) but I surmised rather too low. I had a spare so substituted that which gave proper "changeable" voltage values and indeed the gauges then worked normally.
Re: Fuel gauge reading half-full when empty
Posted: Sun May 05, 2024 10:12 am
by ManyMinors
Excellent progress
I still don't see why you needed to remove the gloveboxes to get at the speedo. One of those little pen torches shone through the access holes will pinpoint the speedo securing screws, which just need to be slackened off a little, but the main thing is that you have fixed your car!
