petrol guage

I have a 1.6 bug eye and the petrol guage isnt working proper , It doesnt move half of the time and when i fill the car it only goes up half way i got took the petrol float out and cleaned it and it seems to be in working order but still the same problem i only know im empty when the light comes on which is no good when in the middle of no were... Any ideas ??

take the float out again, and plug it back in while in your hands, move the float to full position and turn on the ignition

See if the gauge follows. If not then you could have a faulty potentiometer, which is the electrical circuit board on the float. or it could be a faulty gauge or wiring.

First I'd swap the floats
Second swap the gauge
Third would be examine and test all wiring