Some clarrification...
Pressure Refueling Rigs do not pump!!! If you mean hydrant dispensers/cart they rely on the pressure of fuel released from a hydrant system...upto 150PSI, reduced by point of delivery at wing. It is possible to achieve fuel flow rates of upto 4,000 litres+ using hydrant pressure refuelling
Refueller/bowser vehicles (big tank vehicle with wheels) do pump fuel and can still fuel underwing but typically at lower flow rates.