I bled my brakes sunday and it drove fine that day. Then i drove it to school yesterday and the pedal seemed pretty stiff. Today I go to drive it and i had no pressure on the brake pedal but just enough to stop. I think I have an air bubble* in the lines because I know my master cylinder is squirtin out fluid. I know my proportioning valve is bad too. I also have bad front brake rubber lines in which I am changing out tomorrow along with the valve. Any other ideasd besides air in the lines to cause that bad brake pressure?

 

busted line possibly. that or you didn't tighten up the bleeder screws very well