Fuel pump blues (i give up).

Sounds like the pump is not keeping up with the G-force demands. Did you change anything other than the pump between these runs and when you ran 1mph quicker?

Fuel level when you made the runs?

How high is pump in relation to the cell?

How well is the pump grounded?

Any unusual bends or kinks in the line? Have a filter before and after the pump?

Where is the regulator installed?

Electrical system healthy otherwise?