Pushing the plate down (doesn't matter if the key is on or off, just need pressure/FPR jumpered) will show you w/ the injectors removed if the FD is moving fuel..
Sometimes after sitting for a while you can blow things out by undoing all the fuel lines @ the dist. and pushing the air plate to WOT.. If it's working properly it will flow quite a bit of fuel, so be prepared!
I've taken apart FD'ers and the part that Usually fails (the main diaphragm) isn't available...as such I use CIS Flowtech units. They work Great, Larry Knows what he's doing when it comes to CIS/CISE.
Jonathan