There are several things that could cause this issue. You for sure need to check for leaks, the master cylinder could be bad, and the booster could be bad. Could be as simple as a vacuum leak.
Matthew Vaughn
O’Reilly Auto Parts
Have a 2000 S10 new brake pads front, new shoes and drums rear also new master cylinder.
Have a 2000 S10 new brake pads front, new shoes and drums rear also new master cylinder. System has been bled twice and still pedal goes slowly to the floor. This was happening prior to the brake job also. I have pedal when the engine is off however once it cranks and you hit the brakes the pedal goes to the floor.
