How To Measure Fuel Volume.

The bucket test will be the easiest. A holley blue pump is rated at 110 gph, Flows 88 GPH at 9 psi, so at 6-7 psi I'd think you'd want a little more than a gallon a minute as 9 psi is 1.46 gallons (88 pgh/60 mins = 1.46). I honestly don't think fuel is your issue. Can you provide more specs on your engine.