The ability of the pump to pull a depression on the pick up tube is controlled by RPM and gerotor sizing. I have run a standard volume pump with a 1 inch pickup tube and ever found a priming issue.
Good to know. I'm speaking more generally as something to consider since it will take more revolutions of the pump to clear any airspace in the pickup when the pickup tube is enlarged - enough to matter? Not likely outside of an OEM type application that requires maximum longevity.
