Brake pedel pushes to the floor

little low fluid w/no sign of leak is fluid going into calipers from pad wear ---causes of brakes to floor --need brakes replaced--failing master--air in lines--leak--flex line failure--caliper failure

Not bleed properly
or you have a rusted out line (leak)

There is NO Procedure-- that when driving a
vehicle or bleeding brakes,do you ever pump them

Brake line busted somewhere? Is the linkage to the master cylinder intact? Master cylinder might have been installed incorrectly.

I would go with not bled correctly

The booster should hold up with a hard pedal until
you start the engine, then vacuum causes it to move
down when pressing on the brake

power brake booster is blown if the pedal goes to the floor and everything you stated was done correctly

There may be air in the lines. Bleed all your brakes starting at the farthest wheel from the resevoir, and finishing at the closest one. Try the pedal after its bled. If the pedal still feels soft or travels to the floor there may be a pinhole leak that may be spraying on the underbody of the car, or the seals in the master cylinder are gone filling the vacuum booster(if equipped). Air compresses more than oil so if bleeding works that may be the problem.

you have air in the system or the master cylinder is going bad. Have a shop inspect and bleed for safety reasons if you can afford it.

Master cylinder is toast.

bleed brakes again you got air in them .check make sure master cylinder is low on fluid.

Master is internally bypassing : replace or rebuild.