Today i was riding with my dad in his 1995 F-150. While pulling up to a stop light his brakes went out. The pedal went right to the floor. After a few blocks the pedal came back and the truck stopped fine. This is the only time it's done this. He hadn't done much braking, it was just normal around town driving so i doubt that the fluid boiled. Could there be a problem with the master cylinder? He drives an hour on the thruway every morning to go to work so to lose the brakes unexpectedly would be bad.

-Jon

 

I suspect the master cylinder needs to be rebuilt. I would play it safe and do that as well as bleed the system.