If the brake pedal on a 1987 buick regal t-type presses hard but not to floor and takes all of your weight to stop it is it the powermaster brake system?

2xxbqYes and no. There's a series of diagnostics to follow to determine the cause, however the most common one is the accumulator ball (the black thing on the side of the unit). They lose pressure over time unti they need to be replaced. Look to http://www.gnttype.org/techarea/brakes/PwrMstr.html for more information. Hope this helps!