I have an 89 na jetta and I am getting air in the return line from the pump and air in the injector balance lines. The car runs fine and does not smoke. I have tightened all the clamps and still getting air in the lines. There is not any air going into the pump. Is this the front seal on the pump or just normal? Like I said it runs fine. Just took it on a trip from GA to PA and got 52MPG HWY
Are you sure you aren't getting air at the pump inlet? rev it up and down and watch it for a bit.
After the car has sat overnight check the fuel inlet and see if fuel is draining back to the tank?
Otherwise perhaps your return lines are simply worn. Get some high quality hose and get some extra, I always carry some. Try and replace the runs and check again.
tighten the feed line a bit, or replace the copper washers. if that doesnt fix it, then its the pump seal.. once they leak, they never fix themselves..