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MG MGA - Fuel Guage Flicker

Hi All I have a slight problem with my fuel gauge. with the ignition on either engine running or not the gauge needle is jumping all over the place. It gives a general idea of how much fuel I have but its not constant?? Any ideas please. The car has been converted to negative earth but before my ownership.
Thanks Paul
p anderton

This happened to me and I found there was a fault with the fuel sender unit. The electrical circuit of the unit starts at the metal body which is earthed to the petrol tank and passes across to the coil wiper shaft. If there is a lot of wear in the shaft the contact to the body becomes intermittent causing the fuel gauge needle to jump around. You could try a new repro. sender unit but these are notoriously poor.
What I did was to drill and tap a 6BA (I think) hole in the sender unit body close to the shaft and I fitted a beryllium copper flat spring from a 6BA screw which pressed against the end of the wiper shaft thereby giving a better electrical contact. This did the trick.

However, before taking out your sender unit I would first make sure you have no loose contacts in the circuit especially at the back of the fuel gauge. ...............................Mike
m.j. moore

Thanks I will have a look tomorrow. I've cleaned the electrical connection and run a separate earth from chassis to the screw of the sender body but it's made no difference. Seems to flicker between 1/2 and full. The tank is, I hope !! 1/2 full
p anderton

Just checking, it is flicker and not sloshing fuel? I am sure you already know, but the fuel gauge is not damped so much so the gauge will move around as the fuel moves.
Neil McG

no its flicker as its doing it whilst stationary with the ignition on. I'm thinking it might be power to the fuel pump ??
p anderton

No that flicker is nothing to do with the fuel pump, as Mike says its the sender unit. I've got this flicker too. Mike I like your elegant solution and I just happen to have a 6BA tap and screws...
I have checked the resistor coil several times and thought there must be gaps in the coil where the wipers weren't connecting, but your theory makes a lot of sense. Now when I eventually use up that tank of fuel...
Just imagine, after 17 years of ownership, a steady fuel gauge that doesn't say empty half the time - unaccustomed luxury..!
Pete
P N Tipping

This thread was discussed on 15/05/2014

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