fuel supply - at my wits' end!

[cstanley]

i can't figure it out. i must be missing something simple. i still can't maintain fuel supply after about 5 miles of run-time. i've replaced hoses, fuel pump, fuel cap, and tank sending unit (good news: fuel gauge works now!) i just can't figure it out! (see this post for my symptoms: http://www.67-72chevytrucks.com/vboa...d.php?t=191092)

i did, however, notice last night that the front vent hose (not yet replaced) that attaches to that smog canister by the battery was disconnected, and the restrictor inside the hose was shot. also, the cap on the canister looked to be missing. it hasn't always been that way, but i can't remember when it might have come off. could this be my problem?

maybe pressure is keeping fuel from flowing to pump? problem seems to be on the supply side of the pump. when it stops flowing, i disconnect the supply from the pump-no gas, but after a few moments, it will start to flow again.

I AM SO FRUSTRATED WITH THIS!!