Damned fuel gauge

[timberman2004]

doing my nut here with the fuel gauge ...so can someone follow my logic pls ?

Originally the needle flew to way beyond the full mark, and then at a shade under 1/2, I ran out of fuel, but 230 mile to the tankful
fettled around to try to correct...now the position is reversed

fuel gauge needle is moving ...but to the wrong place !!
Switch on and it gently moves up to 1/3 full... but there is a known 5 1/2 galls in the tank ..so it seems the gauge is operative ?
I've changed the Voltage Regulator on top of the speedo rear 3 times ...no improvement, so i surmise the VR is OK

The sender must be sending some sort of voltage to get the needle to move ?
wiring must be OK for the same reason ?

that just leaves replacing / re-bending the sender arm ?
I'm a shade leery about this, as I have to strip out the 1971 Traveller back tray to get at the sender ... but if needs must

am i missing something ?

[geoberni]

A multimeter might prove useful to look for poor connections.

It's NOT a voltage regulator, it's a stabiliser, to give you a 10v supply for the fuel gauge. Basically it's small heating element and bi-metal strip with a set of contacts opening and closing several times a second.

To save explaining it all here, see this Mini website: www.minimania.com/Smiths_Voltage_Stabilizers

Halfway down the page there is a fault-finding list of faults and what to check.

[timberman2004]

yes indeed ...it is of course the voltage stabiliser ...senior moment there, cooking and typing

[oliver90owner]

One fault not considered might be that of the supply voltage. It won’t work satisfactorily if the supply is restricted. Doesn’t happen often, but it can.

Of course, some indication could possibly be checked (for this fault) with a test lamp - but a multimeter is so much more convenient for most tests.

I don’t ‘surmise’. I check things out to be sure/confident of what is going on.

[myoldjalopy]

If it was working OK before then I wouldn't touch the sender arm - why would that have changed?

[ManyMinors]

Removing the sender shouldn't involve much work. You don't have to remove anything else from the car. There is sufficient space above the tank once the spare wheel is removed. I would suspect that the sender unit is at fault. It is possible that bending the arm might rectify the problem. It is probably worth a try anyway. It won't cost you anything except 15minutes and perhaps a new gasket.
Make sure the tank isn't full though!

[geoberni]

One fault not considered might be that of the supply voltage. It won’t work satisfactorily if the supply is restricted. Doesn’t happen often, but it can.

Of course, some indication could possibly be checked (for this fault) with a test lamp - but a multimeter is so much more convenient for most tests.

I don’t ‘surmise’. I check things out to be sure/confident of what is going on.

Exactly. Far too many people leap around all over the place with electrical faults and don't check the basics.
Is there actually a full 12v at the input to the VS?
Looking at recent past posts by timberman2004, there's no clue as to if the car has been started or if the battery is in good condition?
As I recall, he has spent a reasonable amount of time fiddling around with and behind the speedo, so not beyond the realm of possibility that a cable has come loose. Loose or damaged cable can easily result in voltage drop, which reduces the supply to the VS.

Since the Tank Unit hasn't been disturbed as far as we know, that puts if further down the list of possibilities than the area which the OP has been fiddling around it.

[Nickol]

By removing the sender wire from the tank connection and earthing it, the gauge should then read full. That would indicate all is ok with the gauge and its elektrics . If it does not, then the investigations can begin.