If the needle is still in the dash cluster, then its the pick up pump in the gas tank I'm sure. The electrical sender may have gone out on the "in tank pump" Not super positive, but I'm sure its pointing in the right direction. I've chased down a lot of the issues in my 88 Jetta and have found that its usually something simple. That pump is easy to check and replace. There's no real pressure involved with that pump, so don't be worried about fuel exploding everywhere. You may be able to fix the sender on that pump as well. If it hasn't gone out.