[hammermill]

When I press on the brake pedal it goes to the floor. If I pump it up it slowly bleeds off and makes a swooshing sound under the dash. What could this be?

 

[klhansen]

Very likely a bad master cylinder.

 

[DENNY]

I would agree but it would help if we knew what we are talking about is this a go cart or what year car/truck/moped???? Take the time to go to YOUR home and put your truck/car/moped info into the sig like Klhansen has. Once done it helps for every question after that.
DENNY