fuel gauge not working

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cococola
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fuel gauge not working

Post by cococola »

My fuel gauge on my Morris Minor convertible has never worked since I recently purchased her and I find it will only read between a quarter of a tank to empty.
Car is 1963 with a gold face.
New sener in the tank recently replaced.
If I earth the sender nothing happens.
Any advice with testing and tips I would be very greatful.
Morris Minors..... such fun :D
ManyMinors
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Re: fuel gauge not working

Post by ManyMinors »

For a start: Have you fitted the correct type of sender? The sender for the gold faced gauge is completely different to that which operates the black faced gauge :wink:
jagnut66
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Re: fuel gauge not working

Post by jagnut66 »

Abby dated to 1963 and she had a gold faced speedo, so that is correct for that age of car.

The gold faced fuel gauges are something else that can be hard to find, though you can adjust / repair them if you want to have a go:

viewtopic.php?f=4&t=54012&hilit=fuel+gauge
Best wishes,
Mike.
Last edited by jagnut66 on Mon Jan 24, 2022 4:18 pm, edited 1 time in total.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
simmitc
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Re: fuel gauge not working

Post by simmitc »

If I'm reading correctly, it's a fuel gauge problem, we're not looking at the speedo.

Cam we clarify: "If I earth the sender nothing happens.". Exactly, the sender is already earthed by being attached to the tank. Do you mean that you took the wire off the sender and connected that to earth so that the gauge should have been earthed?

This could be the wrong sender, a broken wire/poor connection or a faulty gauge. Do you have a multimeter to assist with testing?
jagnut66
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Re: fuel gauge not working

Post by jagnut66 »

If I'm reading correctly, it's a fuel gauge problem
Yes and the O/P states that it has only ever read between 1/4 full and empty, so it must either want adjusting on the rear of the gauge, or he may have a dodgy gauge, tank sender or earth(s).
If he removes the live feed to the sender on top of the fuel tank and earths it, would I be correct in thinking that a good working fuel gauge will read full or is that the other way round (something I've not tried before)?
Just trying to think of an easy test if he doesn't have a meter or doesn't know how to use one.
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
ManyMinors
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Re: fuel gauge not working

Post by ManyMinors »

jagnut66 wrote: Mon Jan 24, 2022 3:29 pm Abby dated to 1963 and she had a gold faced speedo, so that is correct for that age of car.

The gold faced fuel gauges are something else that can be hard to find, though you can adjust / repair them if you want to have a go:

viewtopic.php?f=4&t=54012&hilit=fuel+gauge
Best wishes,
Mike.
Mike. I wasn't suggesting that the gauge was wrong. However the OP says that he has recently replaced the sender unit, so my question was: Has he fitted the correct sender unit to suit the gauge he has. It is important that the gauge and the sender are compatible :wink:
cococola
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Re: fuel gauge not working

Post by cococola »

Update of details ..
Fuel sender unit was replaced by the previous owner so I'm not sure if it is the correct sender,I did remove the sender and I can see that it is brand new condition.

When I earthed the sender I ran another wire from one of the fixing screws to a good earth and nothing happened.
I also removed the wire to the sender unit in the tank and took that to an earth to see if the gauge went to full..no reading at all.

Yes a fuel gauge problem not a speedometer problem.

With regards to adjusting the fuel gauge,would the gauge be this far out to require adjustment..Juat to clarify,the fuel gauge reads between empty and a quarter of a tank with the ignition turned on.

many thanks :D
Morris Minors..... such fun :D
jagnut66
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Re: fuel gauge not working

Post by jagnut66 »

Yes a fuel gauge problem
Option B then:
https://www.ebay.co.uk/itm/384625292780 ... SwcuRhw0~7
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
oliver90owner
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Re: fuel gauge not working

Post by oliver90owner »

I also removed the wire to the sender unit in the tank and took that to an earth to see if the gauge went to full..no reading at all.

Something not quite right here? Something seems a bit - err - fishy. Gauge works, but indicates wrong when installed with the tank sender, but does not work at all if shorted to earth. Can someone explain why that should be?
cococola
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Re: fuel gauge not working

Post by cococola »

Ive looked at the fuel sender units listed and the correct one for my year appears to be the one in the photo, which has an additional control unit on the top. The one that has been fitted to my car has a flat top with just a connection terminal which maybe the later model? If possible can somebody please confirm that their sender unit looks like this please.
Attachments
fuel sender.jpg
fuel sender.jpg (64.71 KiB) Viewed 1803 times
Morris Minors..... such fun :D
MorrisJohn
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Re: fuel gauge not working

Post by MorrisJohn »

cococola wrote: Tue Jan 25, 2022 11:30 pm Ive looked at the fuel sender units listed and the correct one for my year appears to be the one in the photo, which has an additional control unit on the top. The one that has been fitted to my car has a flat top with just a connection terminal which maybe the later model? If possible can somebody please confirm that their sender unit looks like this please.
That’s the same as was fitted to my 1961 Minor 1000 (and I expect my ‘57, I’ll know shortly for certain as I’ve a new gasket waiting to go on there). Both have bronze faced speedos. Sorry that I can’t comment on earlier or later models.
A bad day with my Volksie still beats a good day at work!

https://www.glasgowmoggies.com
simmitc
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Re: fuel gauge not working

Post by simmitc »

Irrespective of whether the sender is correct or not, the basic circuit remains: Supply from ignition switch to fuel gauge, through gauge, along wire to sender unit and then to earth. Thus removing the wire from the sender and connecting it direct to earth should cause the gauge to deflect. If it does not, then there is a problem somewhere in the rest of the circuit.

Disconnect the battery and remove the speedometer. Looking at the wiring diagram for this age of vehicle, I would expect you to find three green wires connected to one terminal on the fuel gauge and a single green wire with black tracer connected to the other terminal on the gauge; and no volrage stabilizer. If those look correct then double check that there are no wires or terminals in contact with the car body and then reconnect the battery,

Disconnect the green/black wire. Switch on the ignition. Using a multimeter, check that you have 12 volts between the 3 wires and earth and then the other terminal and earth. Using a small fly-lead, connect the empty terminal to earth. Does the gauge deflect fully? Switch off ignition. If you have 12 volts on 3 wires and none on the other terminal, or the gauge does not deflect when earthed, then the gauge is faulty. If those tests are OK, then test continuity on the green/black wire. Connect one end to earth and use the multimeter to check resistance between the other end and earth. If you get anything other than effectively a zero reading, then the wire is broken somewhere.
cococola
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Re: fuel gauge not working

Post by cococola »

Thats great it looks as though John has confirmed an incorrect sender and before I proceed to ordering anything I will carry out tests that simmitc has set out fabulously for me over the weekend.I will then report back.
many thanks
Morris Minors..... such fun :D
Bowie69
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Re: fuel gauge not working

Post by Bowie69 »

Whilst on this subject, anyone know of a source of the earlier senders?

None of the usual suspects seem to have them in stock, and haven't done for a very long time.
mowogg
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Re: fuel gauge not working

Post by mowogg »

The photo looks like the right sender for a 63 car. If I recall correctly the later ones have a spade connection and the earlier ones are secured by a nut.


As other suggest I don't think you can mix and match. The gold face fuel gauge will immediately register the tank level when the ignition is on whereas the later ones take a few seconds to equalise.
jagnut66
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Re: fuel gauge not working

Post by jagnut66 »

Hi,
I could only find one in the US:

https://www.ebay.co.uk/itm/360721119217 ... XQAF5RgZzO

However Minor Parts of Oxford may have one, email Richard:
rgplant@minorpartsofoxford.co.uk
Failing that try Tom Roy: 01642 723400
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
Boomlander
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Re: fuel gauge not working

Post by Boomlander »

Just ran the very useful test sequence posted on the forum on Willum's apparently dead fuel gauge.
Disconnected the wire from the petrol tank sender unit and connected it via a 3mtr extension cable to one of the main earth points in the engine bay. Switched on the battery and ignition and the gauge moved smoothly up to the full position.
Have ordered a new sender in case the original one is beyond help but can I ask if anything needs to be set up on the new unit or can it be fitted and forgotten straight out of the box?🤔

simmitc
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Re: fuel gauge not working

Post by simmitc »

No adjustment, fit from the box - in theory, but worth running the tankle down and filling copletely just ot confirm operation OK.
Boomlander
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Re: fuel gauge not working

Post by Boomlander »

Many thanks for the help. 😁👍

Boomlander
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Re: fuel gauge not working

Post by Boomlander »

New sender fitted and the gauge is working! 👍

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