Swapped my brake master cylinder the other day and now my pedal travels a quarter of the way before the brakes respond. After I let of the pedal and immediately try pressing again they will grab at the top of the travel. Could there still be air in the system or do I have a vacuum issue?

 

If the pedal is hard to press = vacuum issue.

If it's easy to press, then you have a few possible issues:
1. Air in the lines still from the master cyl swap. I assume you bench-bled the cyl before installing?
2. Too much travel in your rear drums, via the auto-adjusters being old/being pieces of junk and not working right. There is a port on the inside of the drum you can use a flat-head screwdriver on to adjust them. I think up towards the ceiling makes them both tighter, but don't quote me on that.
3. IF your rears are in good working oder, without much wasted travel, the last common issue is:
Air in the RABS(Rear-anti-lock-brake-system) valve, located inside the drivers frame rail, right below your door lever-ish. Most of us that have this issue unscrew the big valve seal, take out the spring, and re-seal it. Then bleed again, and your brakes should be solid! There is a bleeder port on the valve itself.

That's my best shot, the RABS valve one is pretty amazing in the difference it makes. It will disable your RABS if you still have it working though.

-Joshua

 

Now that you say that my Rear anti brake light has been on. Ill give that a check tomorrow. Thanks for the info