A "fast" pump will only have a barrel of a larger volume allowing you to push a larger amount of air per stroke.
Your first pump on a flat tire is going to put the greatest volume of air into the tube. With each successive pump, the volume will decrease as the tire pressure increases.
You can figure out the math for yours based on your pump, tire, tube, rim, atmospheric conditions, duration of inflation, etc. But if one thing is different on my set of variables, my results will be different.
Last edited by jjvw; 04-30-08 at 09:47 PM.