I've bought a 1988 Honda Accord (3rd gen) with an issue where the fuel gauge always reads full.
I removed the sender unit from the tank and cleaned it with some contact cleaner (it was kind of copper coloured). Before replacing it within the tank I tested it outside the tank connecting it to the car and moving the float by hand - the gauge worked fine and responded to me positioning the float.
So, I reinstalled the sender back into the tank. However, now that the sender is back in the tank the problem has returned - the fuel tank reads full again (tank isn't full) and won't drop when I turn the car off.
Would anyone know what could be causing this or have any other ideas?