Vapor Lock(?)

I have a 69 Mach-1  428 car, it is an automatic with power steering, brakes and air.  Well having said that now that it is hot weather I can not drive it across town it shuts down like it is out of gas.  I look in the fuel filter (semi clear plastic) and it is empty, carb bowls are empty.  You crank and crank on it and finally it will pump up gas and re-start (for a few blocks). I have replaced the gas tank pick-up, the steel line to the front of the car, rubber hose to fuel pump, 3 different fuel pumps (Holley, stock, and now an Edlebrock) same results.  I have like 7# of fuel pressure on the gage and get this even when the filter is empty with the car starved out shutdown on the side of the road I have like 4+# showing on the guage until I take the hose loose.  Oh btw the carb is a Holley 850 Street Avenger.  I am out of ideas please any help will be appreciated .  

do a fuel pump volume test....

totally disable the igntion system... points... pull the negative  wire off the coil... this prevents the ignition system from sparking..  not a good thing... when working with open fuel lines....

pull the fuel line off at the carb....    put some longer fuel hose on the end...

run that into a gallon plastic bottle...  

crank the engine for 10 seconds...    while watching the fuel pulses into the bottle...

each one should be the same as the previous..   large.. and full...  if they get smaller... and smaller.. i would look for another filter in the system thats clogged... crushed fuel lines somewhere...  like right behind the left front tire... where the fuel line runs under and around the frame...

i have also found sediment filled fuel lines.. i have used a new universal speedometer cable... a few friends and a variable speed drill.. to spin the full length of speedo cable into the fuel lines.... keeping it tight and straight except for the guy right at the hard line...  and he is holding the casing as it spins... the twist of the core pushing it in the hard line... then flushing with slow drying cleaner... like carb cleaner... and compressed air..

when the lines or filters are restricted.. the suction lowers the pressure on the suction side of the fuel pump...  this allows any heat to cause the fuel to boil.. (vapor lock)   the fuel pump cannot pump vapor ...   at least when it is hooked to the carb...

i went through this on friends cars and on my 460 econoline van...  drove me crazy... there was enough dirt in the fuel tank... that after i changed the filter the first time.. it clogged again...  and i did not realize it...  

i did notice that at autozone.. there is a E3903 fuel pump.. that fits in tanks.. is short... and puts out 5 psi... so you might want to examine your fuel sending unit.. see if this intake pump will fit.. with some mods to the bulkhead connector to supply it with power... it does require a strainer... so plan on one.. there are many to look at ... most will fit.. some will fit right...  

  clogged strainers on the pick up in the tank...