1998 A8 gets no fuel when tank is less than 1/2 full
Simply put, the pump is not at the lowest part of the tank, but sits in a plastic baffle and this suction system keeps the cup filled and the pump submerged.
I think I had the most miserable fuel pump replacemnt process known to man - a worst casee scenario where I had to weld up a special foot long hole saw and cut out the fuel pump assembly around the retaining bolt. Search "Das Boot" and you will see what I mean, The catch 22 is, replacing the fuel pump is EASY, once you know how.
When you replace a fuel pump put in a gallon or two to an empty tank, then pop the cover off the fuel pump relay and lay a rubber handled pliers on the contact to hot wire the pump. Buy a banjo fitting to attach to the High pressure output and add three feet or so of fuel hose. Let it pump into a fuel can. If it starts strong then after a few seconds begins to aerate and spit...its is wrong...try again..once it pumps out all but ..say...a half gallon or less.. you ae good to go. This is a hell of a lot better then the Audi reccomended method of "Go for a drive and run out of gas" Good luck. Random thoughth...WD-40 makes the tough job of getting the rubber gasket back in EASY.




