Fuel gauge woes

[getunder]

I have done Search but before trying some of the advice thought I might find out more. I removed the tank to do coolant pipes. Replaced tank but zilch on fuel gauge. Took it off again and checked connection was on. It was and firmed in. Are the pins polarised i.e. does it matter which way round the two pin plug goes into the sender unit.Put in a measured 4 gallons and tried again. Still Zilch. Silly but can't remember if engine has to be running for it to register or just two clicks ? Tried it on road including hills and braking suddenly in case the float was stuck and petrol surge might move it. Is the sender prone to stick when fuel drained completely ? Dropped the tank about 5 years ago but had no problem then replacing it. Was working fine until doing job. Am living up to my username

[weldore]

connect both wires at the sender together,if the gauge goes off the scale its the sender...dont do this till someone else on here says it will be ok to do it tho..im just guessing

[Grun]

One side of the sender (Lilac/Black wire..... when disconnected) should have 10 volts on it with ignition on (If memory serves........Voltage stabilizer output.)
'tother side of sender (Brown wire) should go to earth (Front cross member left). Mr Haynes says.
The gauge has a bi metallic strip inside with a heating element, the 'sender' varies the resistance to earth and therefore the current passing through the heating element, which in turn varies the deflection of the bi metallic strip, and hence the needle position.
Or sommert like that.
AngeloEvs is the forum Guru on things of this nature, and will be along to correct me in due course
Mike

[getunder]

Cracked it !! Oh joy of joys. checked connections as per previous advice. no joy. Nothing for it, tank down again. Draining petrol is the longest part of it. (4 gallons). Halfords do a useful 2 gallon DIESEL plastic tank but not 2L petrol. Label well. In the vicinity of the sender unit a Brown wire comes out of the loom above and should have been attached to a connector self tapped to a thin narrow horizontal shelf just to the rear of the cross member which is the one between the tank and the spare wheel. Well rusted and gunged up it was difficult to spot and impossible to unscrew so drilled a new hole for new crimped on connector.

[getunder]

Noticed that the protruding thread of the self tapper that fixes the earth wire to the chassis can be viewed about 2 and a half inches on the inside of the chassis in a tapering horizontal small shelf. This can probably just be reached to check if the earth wire is actually fixed to the self tapper but not the quality of the earth itself. hope that makes sense, it's just a very quick check without getting tank down.