Fuel Gauge Problems

Hi Landy lovers, My 91 defender fuel gauge is doing my nut in, I have replaced the gauge & the sender unit plus run new wires from the sender/tank unit to the gauge and fuel warning light. I filled the tank to full and the gauge only reads just above 3/4 full. When I drive, the gauge,s needle moves about from 1/4 to 3/4 depending on going around corners etc.After covering about 250 miles the gauge drops of the scale (well below empty) but the warning light comes on and will flash on/off depending again on driving around corners etc. I know the gauge, sender unit and wiring are all okay but can anyone tell me if there should be a voltage stabilizer or some other device wired into this circuit ?

Try posting this question in a section that hasn't got the top title 'Do not post questions in this section'.

You'll be amazed the help you'll get.

Thanks for that,new to this.