88 Thunderbird rear break pressure

88 T bird has now pressure to the rear breaks. I blead them and get only drops. At the master cylinder there is press from the two lines that go to the front but when I pull the line to the rear theres only a drizzle. Replaced master cylinder and have blown all lines clean. Please help, it's like the master cylinder builds press for the two front lines and then the piston doesn't go any further to make press for the rear.:banghead:

Did you bleed the new master cylinder before you installed it? Buy a couple of short brake lines that fit the outputs of the master cylinder. Bend them around so the other ends are inside the master cylinder near the bottom of their respective bowls and then fill the bowls with fluid. These ends need to remain submerged in fluid! I usually have the master cylinder clamped in a vice and use a screw driver to push in on the piston as far as it will go. Push in the piston slowly so you don't spray fluid all over the place! Do this until you see no more bubbles in the bowls. Install the master cylinder in the car, remove the bleeding tubes and install the brake lines. Bleed the brakes going in order from RR, LR, RF, LF. Have someone pump the brake pedal 4-5 times and have them hold pressure on the pedal while you open the bleeder screw. When the pedal goes to the floor, close the screw before they release pressure on the pedal. Repeat this at each wheel until no air bubbles come out of the bleeder screw. You can attach a hose to the bleeder screw and insert the other end into a clean, clear jar that has enough brake fluid in it to cover the open end of the hose. Keep the hose end submerged and watch for bubbles.