help with fuel system problem?

[low 84]

okay i am having a problem with the fuel system. i can't get gas to the mechanical pump. i know the pump itself and everything after is fine (carb, filter, ect.). we broke the cam in by running a feed line out of a gas can into the pump and everthing worked perfect so its a problem with something else further back.

what i did was go from the factory set up with a return line, to a pump with just and in and out. i cut the old return line back at the dual tank switch valve and plugged it. it also had a charcole canister line that ran up into the engine compartment and whas just not hooked up b/c i have no emmsions stuff anymore, and it wasn't plugged, so i cut that line as well back by the valve and lef it open to vent, b/c thats how it was before.

so why can't i get any fuel to the pump? i tried it with the gas cap off b/c i was thinking mabey vapor lock? i also unplugged the old return line and let it just vent and that didn't work either. my dual tank switch has never worked so i've just always used the passenger side tank which is the one its stuck on, so there should be no problem there. if i suck on the input line to the fuel pump i can get choked up with vapors so i know its not plugged or anything, but i haven't tried actualy sucking it all the way in my mouth.

does anyone have a selector valve diagram, i know i hooked the feed back up to the right spot but it might be good to see a diagram just in case.

can someone help me, i really want to be able to drive this thing around