On 8/20/2021, Peter Ratcliffe in Preston, Lancashire, England wrote:wrote:
"An article I put together for Preston and District MG Enthusiasts club".

Fitting an MGB fuel gauge to an MGA

My MGA fuel gauge stopped working, and by checking resistances between the terminals it was clear something had gone astray inside. It hadn’t lasted long since it’s last professional refurb.

Whilst searching eBay for a fuel gauge I came across an MGA fuel tank sender that looked different, especially when I read it went from 20 to 270 ohms. (MGA is 0 to 70 ohms) I thought could I fit an MGB gauge, which is easier to obtain, to my MGA.

The sender appears to be an MGB sender mounted to an MGA type plate.

My first thought was that the ad was incorrect but the seller, lotsofclassicbits confirmed that the ohm range was stated correctly and that they also had for sale new fuel gauges to match the sender.

I got the sender and the gauge, a 10v voltage regulator, and a different bulb holder.


I checked the resistance with my DMM and found full was 20 ohms however at empty there was infinite resistance, and a little back from empty just under 200 ohms. So it seems like the slider goes past the end of the resistance wire.

With the aid of Chicagoland MG clubs tips on calibrating the thermal gauge I adjusted the stops on the sender to get 20 Ohms full and the largest available resistance before it went to infinite for empty. I then calibrated the gauge to get full and empty to match these resistances.

It appears that with the stop set as I have it the float is about ½” (12mm) off the bottom of the tank, however I know the fuel pump on my car doesn’t suck the tank empty, so I didn’t bend the float arm. I suspect the pick up pipe on my remanufactured tank doesn’t go all the way to the bottom.

All fitted and wired up and it appears to work fine.

My next step will be to run the tank down to empty, then fill it up gallon by gallon and make a note of the gauge reading.

The sender and gauge are manufactured by Caerbont Automotive Instruments Ltd, Abercrave, Swansea SA9 1SH Wales.

Both are available from “Classic Bits” eBay shop, based in Stanstead Essex.
https://www.ebay.co.uk/str/classicbits.