Brake troubles 2003 2500HD with Hydroboost

[izzy_Britton]

Bought a 2003 GMC Sierra 2500 HD, that i am calling a complete and total basket case.

The previous owner had some brake issues over the coarse of ownership and rather than fix the problems he just eliminated the problem. by eliminate, i mean he removed calipers, brake lines, rotors, shoes, blah blah blah.

As a result of the PO's shenanigans, I have replaced the following parts with all NEW parts:

4 rotors
4 calipers
2 front flexible brake lines
1 rear flexible brake line
all brake pads
rear park brake shoes
master cylinder
hydrobooster
power steering pump

There seems to be little to no pedal. The pedal doesnt build pressure while pumping the pedal. With the engine off, if i remember correctly, if you depress the pedal a few time the pedal will get rock hard. This truck doesnt do that, not even a little bit.

I took the truck for a short 5 mile drive last night and there seems to be a drag on one of the rear brakes, ever so slightly, I can hear the drag with the windows rolled down but i cannot feel a drag.

Any ideas why the brakes will not build pressure?

the ONLY other part that i have not replaced is the ABS unit. I have a used one of these but i dread putting it on.

-Izzy