2003 Buick Century Custom 6 Cyl 3.10L
brakes fade to floor.
I replaced frond disks &pads and bleed brakes, on test ride light stayed on and brake pedal has little pressure. I bled brakes again . no change I disconnected vacume line to booster and brakes were firm. replacing line caused original problem to reemerge.
If you pump the pedal and it goes firm but slowly drops while you hold it, there may have an additional leak somewhere or you could have a bad master cylinder, or faulty power brake booster.