why dont i have break pedal pressure?

I had the same problem, it could be a couple different things, first off if you haven't tried bleeding them do that, 2nd what you can do is check out the vacuum line from the intake manifold to the brake booster make sure you check valve is on properly the grommet is in good shape, and see if you have vacuum. Or If you have abs brakes try flushing out the abs module, its on the inside of the frame by the front driver tire, just disconnect the hard line out of the module and pump the pedal until you get a good flow. Or you can try check the 3 way valve on to of the rear axle, disconnect the 2 hard lines going out to each wheel and pump the fluid threw there. Hope this works out for you, good luck...

Did you bench bleed the master cylinder? If you didn't you will have the exact same problem as a bad master cylinder. You still have air in the system.Bench bleed the master cylinder,install it,have someone pump the brakes up and bleed the lines on it once one at a time then bleed all four wheels - one at a time.

you can try bypassing the ABS module by making a bypass w/ a short piece of brake line and two inverted flare fittings as they are known to leak fluid into the accumulator, or you can try cleaning it, My Bronco II has been on jack stands since march because of brake pressure problems

Did you ever find the problem my bronco 2 is doing the same