AA:

Behind the fuel inlet fitting of the FD is a fine mesh screen; it may be clogged.
If that screen is clear, the FD could be removed, and an attempt made to ensure that the metering plunger is free to move. To do that, mark the location of the seal holding nut on the bottom of the FD (it is an adjuster for the stop position of the plunger), and then remove the nut. The plunger will now be exposed in its bore, and can be soaked with a thin penetrant.