A4 Fuel gauge problem

Having done a search through the newsgroup, I can see that fuel gauge issues are quite common, but none seems to fit exactly with what I'm experiencing. So if anyone out there has any light they can shed on
this, I'd be very grateful!
I've recently bought a '96 A4 1.8 petrol. I've noticed that when I do a sustained speed of 60mph+ for more than a few minutes, the fuel level *appears* to drop quite alarmingly. Having started out this morning with around 3/8 of a tank of fuel, by the time I had covered 25 miles at around 70-75mph, the low fuel indicator was lit and the gauge was on the red. To be on the safe side I put a little more fuel in and carried on. When I reached work and let the car sit running for a minute, the level returned to exactly where I would have thought it should be.
I'm no expert with automobiles, and this is my first Audi. So please don't assume I've carried out even the most basic checks; please feel free to suggest *anything*!
Many thanks, S.
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Have a look on www.Audiworld.com There's an article on cleaning the fixing the sender in the fuel tank.
You could also use VAG-COM to check for any fault codes and then monitor the information the sender is reporting. A company called RossTech sells the software or alternatively find someone in your area with the software.
Hope this helps
Richard
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