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Ecosse

TR3 Fuel Gauge

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Afternoon All,

After 63-years my fuel gauge has decided it has had enough, it still works, but needs a flick on the glass to spring into action and seems to read low. I can get a replacement for £75, but just wondered if anyone has any hints as to how I can perhaps remedy the situation before purchasing a replacement.

Thanks.

Cliff

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May I suggest you get in touch with 'Lebro', ace fuel gauge fixer?

Rod

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Actually I have been searching on the forum to see if there was a tutorial for checking the fuel gauge sender. Couldn't find anything.

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14 minutes ago, TwinCamJohn said:

Actually I have been searching on the forum to see if there was a tutorial for checking the fuel gauge sender

For a TR3A the sender resistance is 70 Ohms when full and zero when empty, according to this site:

https://www.britishcarforum.com/bcf/showthread.php?33663-fuel-gauge-sender-TR3A

Edited by RobH

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With the key turned on, take the supply wire to the sender, easy pull without disturbing the tank, and put the wire to earth, if the guage swings to full, the guage is fine and the sender is U/S, If the guage does not steadily move to full, then it is the suspect, probobly just needs a clean.

 

John.

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26 minutes ago, John Morrison said:

With the key turned on, take the supply wire to the sender, easy pull without disturbing the tank, and put the wire to earth, if the guage swings to full, the guage is fine

Not on the early cars I think John.  I believe they work the other way round. Your description is right for a meter with bimetallic operation, maybe not for the moving-magnet meters in 2s and 3s. ?

This link is from the dark side but the info on troubleshooting is good:

http://www.mgaguru.com/mgtech/electric/fg104.htm

Edited by RobH

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21 hours ago, rodofcv said:

May I suggest you get in touch with 'Lebro', ace fuel gauge fixer?

Rod

Happy to take a look.

Bob.

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2 hours ago, RobH said:

Not on the early cars I think John.  I believe they work the other way round. Your description is right for a meter with bimetallic operation, maybe not for the moving-magnet meters in 2s and 3s. ?

This link is from the dark side but the info on troubleshooting is good:

http://www.mgaguru.com/mgtech/electric/fg104.htm

That link says you can't use a digital meter. Why would that be ?

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Good Afternoon All,

Thanks for the info. The gauge swings to full with the feed cable disconnected, and the gauge works, albeit slowly to full, when the operating lever in the tank is manually lifted using a piece of bent rod. I hope it is not the sender, which was replaced a number of years ago when I installed a new fuel tank, the issue is getting the sender out as I have a fireproof bulkhead installed.

Bob, Would dismantling the gauge and giving it a clean and some WD40 be a good idea, unfortunately we live at opposite ends of the UK.

Thanks again to all.

Regards,

Cliff

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I guess he is saying that because when you are looking at a quickly varying voltage a digital meter shows just a blur of numbers. Much easier to watch movement on a needle. 

Edited by RobH

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Send it to Bob who worked on my gauge . I sent him the gauge and the sender and now it all works properly. There are these experts on the forum and we are very lucky.

Send it by post quick

Richard & B

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If a flick on the glass makes the gauge work, I don't see how it can be the sender.

I used the info on the mgaguru page to sort out my fuel gauge.  When I bought the car it had a sender and gauge from a later car.  I acquired the correct gauge and then found that the sender was back to front.  Being a cheapskate I took the sender apart and reversed the wiring on the rheostat and re-calibrated it to the gauge.  It now works fine albeit the needle stays on full for a long time and once it starts to move it moves quite quickly down to quarter tank at which point you need to be looking for a refuel stop.

Rgds Ian

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Thanks RobH.

I've just ventured into the 'Dark side' and purchased an MGA. At least I'm not alone in this travesty, one of our previous chairmen had one for many years, albeit I recall a Twin Cam Coupe.

Guess what, switch the ignition on and the fuel gauge zooms over to full.

Did look at the wsm for the car but unlike the TR equiv which explains how to check for faults in the sender unit, that published by BMC for the MGA doesn't even acknowledge the presence of fuel gauge or sender unit. Your link to MGAGuru was most timely

We TR'ists dont know how lucky we are!

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7 minutes ago, Adam Blackaby said:

Thanks RobH.

I've just ventured into the 'Dark side' and purchased an MGA. At least I'm not alone in this travesty, one of our previous chairmen had one for many years, albeit I recall a Twin Cam Coupe.

Guess what, switch the ignition on and the fuel gauge zooms over to full.

Did look at the wsm for the car but unlike the TR equiv which explains how to check for faults in the sender unit, that published by BMC for the MGA doesn't even acknowledge the presence of fuel gauge or sender unit. Your link to MGAGuru was most timely

We TR'ists dont know how lucky we are!

Adam, you have gone to the dark side!

Motoring Grimly

The MGA Guru is exceptionally helpful.  Good fault finding and info for all older British car owners.

Peter W

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If it works with a flick of the gauge it is probably just the earth for the gauge.

Take the gauge out and clean up everything. It should be fine after that.

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+2 Sometimes an extra earth cable from under the knurled nut to somewhere suitable on the body helps.

Miles

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Good Afternoon All,

Thanks to all who proffered advice on my problem. Following a stripdown and clean, plus an additional earth wire normal service has been resumed. I now have £75 to spend elsewhere.

Regards,

Cliff

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On 7/19/2020 at 12:39 AM, Ecosse said:

Good Afternoon All,

Thanks to all who proffered advice on my problem. Following a stripdown and clean, plus an additional earth wire normal service has been resumed. I now have £75 to spend elsewhere.

Regards,

Cliff

Pleased to be able to help. 44 years in a TR2 I learnt something and am still learning which is the great thing about these forums.

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