[Healeys] fuel gauge calibration

Alan Bromfield bluehealey at gmail.com
Thu Nov 7 05:14:36 MST 2013

Bob is referring to an excellent set of articles explaining how the sender
and gauge works, how to repair and how to calibrate. But be careful! After
carefully building a calibration switch as described in:
I used it to calibrate my BJ8 gauge (which I had at the time). With a full
tank the gauge read just above half full - dammit!! Unfortunately a couple
of other club members had also used my new switch box to calibrate their
gauges with very similar results.  Strange.
Barney Gaylord (MGAGuru) uses the value of 68-70 ohms as the sender
resistance for a full tank. To check my BJ8 I disconnected the Green/Black
wire from the 'T' terminal on the back of the gauge and measured the
resistance with the tank full of juice. It gave 103 ohms! That would explain
why the Guru's 68 ohms reads half a tank or thereabouts.  With a handful of
new resistors I rebuilt my switch box and the gauge could be adjusted much
more accurately.

During my rebuild I had to buy a new tank sender for 'BlueHealey'. It came
from AH4H over here (providers of quality kit to the discerning) and is a
pattern part probably from India. That device had a maximum resistance of
100 ohms too which I measured before fitting.

Be careful out there.
(______________ Alan Bromfield_______________)
                (__tinyurl.com/healeyforum _)

-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net]
On Behalf Of Bob Haskell
Sent: 07 November 2013 11:05
To: john spaur
Cc: healeys at autox.team.net
Subject: Re: [Healeys] fuel gauge calibration


See the gauge/sending unit articles at

Bob Haskell
AHCA 3000 Mk I registrar

On 11/07/2013 01:27 AM, john spaur wrote:
> There have been quite a few posts on this issue but none seem to 
> really solve the problem. When I first owned an Austin-Healey it was 6 
> years old and the gauge was fairly accurate as I recall.
> The gauge on the healey was professionally calibrated but it was way 
> off, tending to stick at the full side and then rapidly dropping down 
> to near empty. Recently I calibrated it by removing the sender and 
> adjusting the gauge on the bench but it still sticks toward the full 
> side. When the tank is below 1/2 it will start to read towards the 1/2 
> and 1/4 marks.
> What's the issue with getting the gauge to read more accurately? I 
> think it may have to do with the coils and magnet alignment. I think 
> the coils may be out of plumb (due to bending of the case at the nut 
> attachment) which causes the magnet to be too close to the armature
> Has anyone investigated this? Has anyone been able to get their gauge 
> to read more accurately?
> John Spaur
> '62 BT7

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