1989 Honda Accord no vaccum when I remove the gas cap.

The 89 accord lxi started stalling out like it was starving for fuel, I replaced the fuel pump, I took it out on a test run, the day was warm, it drop ok, around 4 miles, this morning it was cool but not cold, (outside temp). The car started stalling out on me again around the 2 mile mar. I drove to a fuel station, pumped in 3 gals of fuel, drove back home, car was sputtering on me then it died. I restarted the car and it started right up, drove home. I checked the pressure on the gas tank, no pressure at all. Is this normal, or should it have some pressure even on a cool day?

thanks in advance