FUEL GAUGE AND CORRECT FLOAT UNIT

Technical MGB discussion
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hazeldrive
Posts: 3
Joined: Sat Jul 13, 2019 5:22 pm
Forename: Martin
Surname: Edmunds

FUEL GAUGE AND CORRECT FLOAT UNIT

Post by hazeldrive » Sat Jul 13, 2019 5:52 pm

I have owned my Iris Blue October 1964 MG B (chassis number GHN3/47870) for 40 years.
It has a set of Smiths instruments - but am told it should have a Jaeger fuel gauge!
A few years ago I had an issue with the fuel gauge not reading and had the sender unit replaced by a historic garage. But I think they got the wrong one as it seemed to catch, and only register up to half full. A garage then turned the float upside down so it reads full when empty and nearly empty when full!!
Can anyone tell me where to get the correct tank unit? - assuming it should have a Smiths gauge!!
Martin Edmunds

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Paul Scott
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Joined: Mon Jan 08, 2018 8:48 pm
Forename: Paul
Surname: Scott
Location: Milton Keynes

Re: FUEL GAUGE AND CORRECT FLOAT UNIT

Post by Paul Scott » Sat Jul 13, 2019 6:13 pm

Hi Martin,
Welcome to the MGB Register Forum.

It sounds like neg/positive earth problem for it to read back to front. But that is just a guess.

Is your MGB positive earth?

I'm sure someone will have an answer.

Regards
Paul
1975 MGB Roadster
Webguru for MGB Register

Ian Fozzard
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Forename: Ian
Surname: Fozzard

Re: FUEL GAUGE AND CORRECT FLOAT UNIT

Post by Ian Fozzard » Sun Jul 14, 2019 8:26 am

Hi Martin, and welcome.

I think you will need to do a little research! I would recommend getting hold of "Original MGB" by Clausager. This book and the Moss catalogue should give you all of your answers.

I believe early MGBs had all Jaeger instruments ( not just the fuel gauge) but I'm unsure of the change date to Smith's. As far as I know the instrument internals are the same, just the faces are different.

So, find out what your B should have in Clausager and then perhaps get both gauge and sender? (Or maybe a complete set of Jaeger gauges!!).
Should work I think!

Let us know how you get on.

Best regards

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Ian Fozzard
Posts: 391
Joined: Fri Mar 27, 2015 8:18 am
Forename: Ian
Surname: Fozzard

Re: FUEL GAUGE AND CORRECT FLOAT UNIT

Post by Ian Fozzard » Sun Jul 14, 2019 8:53 am

Just to clarify: October 1964 was the change over date from Jaeger to Smith's. A new tank sender unit was fitted at the same time, so it looks like the sender and gauge do have to match (as you seem to have found out by experience!)

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

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George Wilder
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Forename: George
Surname: Wilder
Location: North West Essex

Re: FUEL GAUGE AND CORRECT FLOAT UNIT

Post by George Wilder » Mon Jul 15, 2019 2:55 pm

(British)Jaeger Instruments were of course made by Smiths - since 1929.

There are three types of guages used between 1962 and 1976 - the externally lit ones.

There was a change over point September 64/October 64 according to the Moss parts book dependant upon which engine was fitted.
3 bearing GA engines have Jaeger instruments, 5 bearing GB engines have Smiths. The change over was intermittant between cars 47112 and 48767 then all 5 bearing. So all depends with the car inquestion
George Wilder
1965 MG MGB Mk1
1995 MG RV8
2005 MG TF 135
1959 BSA D7 Bantam

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