I'm working on my 1988 Scirocco 16V with CIS and have found I am not getting fuel to the fuel filter (filter is new). I've replaced the in tank pump which was not working and I've verified that the new pump and the in-line pump (outside of the tank) is running. I've opened the line from the back of the car at the inlet to the fuel filter and run the pumps. No fuel coming out. I opened the line on the bottom of the frequency valve and the pumps are pushing gas out that line. Correct me if I'm wrong but isn't that line a return line? Any help would be greatly appreciated. The car has not been driven for 10+ years but has had the tank emptied, cleaned and has fresh gas.