whatever you do, before leaving the job make sure your lift pump is working, a malfunction is easily masked when manually filling the filter and hoping for a self-bleeding
as a check, with an empty filter, if you open the bleed screw on the filter while the engine is running, after some 30 seconds to 1 minute instead of getting fuel out of the bleed screw, the engine gargles and stops
if the lift pump is dead, the injection pump sucks fuel from the tank through the decanter, the lift pump, and the filter ... it works but 1/ the engine is sluggish and 2/ it puts an heavy strain on the injection pump ... compare the price of a good Delphi lift pump and that of the injection pump
I have seen at least 5 Discos whose owners didn't notice their lift pump was long gone
it's funny how that engine can start rather easily then run (only a little slow in accelerations) while the new fuel filter stays empty, the little fuel drawn by the injection pump goes to the engine without entering the filter cartridge