Think im going for a fuel pump soon

[old Rusty C10]

00 2.2 automatic S10 138600 miles No CEL or anything
truck starts up cold real quick ( i have a full tank)
I drive it all over and it starts up fine and as the gas starts going down the truck gets harder to start..more cranking and a couple of times it seemed as tho it had turned over and it didnt so i had to crank it a second time.
Once i get it going it runs like a champ
get to half a tank and the thing starts right up
drive for about 30 or so miles and shut it off and it took a bit to start it..
Im thinking that its prolly junk in the tank or jamming the fuel pump screen?
or is there something i should be looking at on the fuel rail?
Prior to this the truck sat for over a week except to move up and down in the parking spot . Other than that ive had the truck a month and used it a few times without problem. Its got a locking gas cap so i dont think anyone put anything in my tank
Another thing im noticing that when i start the truck the wolt meter reads low and within ten to fifteen seconds comes up to normal around the 14 mark. The oil pressure goes down but if i shut off the truck for even a couple of minutes and then get back in it reads over 30 PSI then goes down once hot to about 15 at idle... I hope its not a major electrical problem in this thing..
anyone have any ideas?

[1971gmcshortbed]

Do you have a fuel pressure gauge? See if the pressure drops when you turn it off. It shouldn't drop more than 5 psi in ten minutes. If it does you have a bad pump, fuel pressure regulator, or leaking injectors. You can pull the vacuum hose off the fuel pressure regulator and check for fuel there shouldn't be any fuel there. You need shut off adapters at the fuel supply and return to isolate injector/pump leaking down. Hth.