Petrol Gauge and Sender

[Roger]

Like many other A7 owners I have spent many hours in the garage, finishing jobs that never got done.
One of those was to see if the petrol gauge could be persuaded to work.
A Morris 1000 sender unit replaced the original as the Mazak body had crumbled.
The instrument was tested but did not work so I searched the web and found this useful site.
MGA cars
There are several pages with details on how to dismantle rebuild and calibrate the gauge and sender unit.
Mine did not work because the coils had been rotated so the magnets did not work correctly, their position is critical to the working of the gauge.
The tricky bit is not breaking the 0.004" copper wire on the coils!
After several days of testing and calibrating I have a gauge that shows about 1 Gallon = Quarter and 2 = Half full
anything above that is extravagant. Whilst driving the gauge is rather indecisive to say the least, but is still a better result than showing empty all the time. I will keep my home made dip stick as reassurance for a while.


Roger

[John Cornforth]

Hi Roger

Well done for getting your gauge to function, it's a fiddly operation with those fine coil wires.  I quite like the moving iron type, as the needle will "dance" as the fuel sloshes round so it is reassuring that there is something in the tank.

Original senders are about 30 ohms, I think the Minor ones are nearer 80 ohms so they won't be as accurate.  But as long as you know what a particular reading means that doesn't really matter.

[Roger]

Hi John,

Thanks for your comments, as you say as long as I know how empty it is I don’t need to know how full it is. I included the link to the MGA site as that is the first detailed explanation I have found after a lot of searching it gave me the confidence to ‘have ago’.

Roger

[Reckless Rat]

My stick has proved to be accurate over the past 35 years or so. ( it works on 6 or 12 volts). The gauge however is only right once per tankful as it's stuck at 3 gallons. Any problems with stick inaccuracies can be remedied by the spare gallon I always carry just in case.

[Biddlecombe]

Or 5 litres a la francais

[Roger]

Hi RR, 

I too have been using a calibrated dipstick, my grandfather’s 4 foot Woden rule cut to size.
The main reason for fixing the gauge was because it didn’t work, I Like challenges.

Roger

[Renaud]

Or 5 litres a la francais

Oh I'm sure our Scot would very much like 5 litres to the gallon...

[Hedd_Jones]

Mk1 eyeball works well.

[Hugh Barnes]

Though not so well on a Ruby...

[Austin Nippy]

Hello everyone,
I too have been looking, unsuccessfully, for years for a replacement sender unit for my 1937 Nippy. Last night I stumbled across a company called Holden Vintage Supplies.
I gave them the spec for a suitable sender which they assure me matches my gauge. I'm running 6 volt, positive earth with what I assume to be the correct gauge - it's a Smith's unit marked up to 5 gallons.
They have come up with something they think is suitable so I have ordered one. I'll let you know how I get on with it once it arrives. If it works, this may be of help to others who are still relying on wooden gauges.
Best wishes,
Nick