89 S10 Blazer Brake Problem

I've just recently replaced all four brakes and half of my rear brake lines including the rear brake hose. I had about half a brake pedal when before I started the rear's and now I have now brake pedal. Did mt master cylinder just suddenly take a shit sitting in the driveway or what. I've bled all four brakes and get nothing but fluid so it's not a bleeding problem. I'm stumped and really dont want to put a new master cylinder on when I'm not sure thats the problem. Any one have any other ideas on what it might be I would appreciate the input.

Thank You,
branlee33

Have you tried to bleed the master cylinder on the vechile to see if it is creating pressure? You may want to get a vacume pump with brake bleeding kit and use vacume to pull the brake fluid, or take it to a shop that has a vacume bleeding machine and have them bleed it for you. Hope this helps.

Sounds like there is air in the system still.