1977 Volkswagen Van not getting fuel?

Hell, and thanks in advance for your help. VW Transporter van was running fine, was having charging issues, but I fixed them, Then a week later, I was driving and it started to sputter, as if it was sucking garbage from the bottom of the tank. It kept getting worse, until it finally wouldn't start at all. I changed the fuel filter and made sure there was nothing in the line, to no avail. Took the fuel pump off, hooked a jumper to it, and the mechanism still spins in the electric fuel pump, but if the pump was running weakly, would it not deliver enough fuel for the engine to run, or if it was weak and dying would it cause the sputtering? Should I be looking in another direction for the problem?