Brake master cylinder

[leftysdad]

94 Pedal goes to floor when the explorer is running, soft, sponge, no brakes....but will build up some pressure when pumping pedal with it turned off.....bad master cylinder ?
Can the be replaced at home
Thanks In advance

 

[ChildIdenticant]

bad master cylinder ?
Can the be replaced at home

Provided you haven't suddenly lost brake fluid, meaning a leak elsewhere yes failing MC.
And yes. can be done at home. Look up proper "bench bleed" procedure.
Good time to assess whether other parts (calipers, hoses, stripped bleeders) should be be replaced.