1980 fuel pump

I just purchased a 1980 Vanagon Riviera. On first start when the engine
was cold it ran great. But after running for a while [about 30 minutes] it
would start cutting out then stall and wouldent start. I checked the fuel line
no fuel moving through. Checked the voltage on the fuel pump. Its only
getting .75 volts. Changed the fuel pump and filter but still getting the same
result .75 volts with the key turned and cranking the engine. And now it
wont start at all, no fuel moving through the lines at all. Help Please ;-}