London Low Emission Zone - Feasiblility Study

on my 2 tank 95 f150, i failed the fuel pressure something emission test.
Due to previous owner and the fuel filter, I had to cut the line and stop using the front tank; could that be what causes this? Plus, do they sell or check for this at normal garages or stores, so I don’t waste my one more free test.

http://www.youtube.com/watch?v=Yu_moia-oVI

The youtube video shows you on how to use the gauge on the Schedar valve. Really good watch.