Paul, I believe the master cylinder is bypassing brake fluid.  the fact that it pumps up is the key to me.  Others may think differently, but I have experienced this symptom with that problem in more than one vehicle.

DMc

---- Paul <wognacious@GMAIL.COM> wrote:
> Is this what I've heard described as "brake fade?" I'll be going down a hill
> and the pedal feels normal, if there is such a thing, and once in a while it
> feels like the pedal all of a sudden will go right down to the floor board.
> If I give it a quick pump everything feels good again. That feeling of no
> back pressure is a bit unverving when going down hill and I'm sure that's
> not the way it should be. Do I need to bleed the brake line?
> Any insight will be gratefully appreciated,
> Thanx,
> pAUL

--
David McNeely