I would say that you have an issue down stream of the filter sock. Likely the fuel pump. It may be pumping just enough without the sock, but isn't functioning well enough to overcome the relatively minuscule resistance created by the sock.
That's my 1 cent anyway. (My opinions have been downgraded by 50% due to recent wrongness.)
Carl


1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission