I have a 89, GTA with four wheel disc's, and i had a lot of pedal fade and almost no brake pressure everytime i hit the brakes. even when i was in park and the car was on i could hit the ground and have the brake light come on, I later bled the brakes and there was a little bit of air in them, i finally regained the pressure in the lines the pedal is very stiff and brakes fine, until i drive for a long distance of time with out hitting the brakes, I will brake one minuet and it will work fine and about 1/2 min later i have little resistance, and the brake light comes on!, I m not sure what i can do to solve this, is it something much more thant lines,? (Brake booster, master cylinder) Please Help.

 

Going to need a bit more of information here to help you diagnois.

Are you getting air in front and rear brakes? Do you have any brake fluid leaks anywhere? Are any of your calipers wet in any place? Do you have any leaks around the master cylinder?

The brake system is not just going to suck in air. You will most likely have a leak someplace.

 

the seals could be blown out in the master cylinder

 

If that is the case the master cylinder should be leaking some.

 

look behind carpet on inside of firewall

 

well i was kinda talkin about losing pressure because the seals are gone around the piston in the master. kinda like when the rings wear in your motor you lose compression. i've seen it before.

 

thanks i will have to chech these all out sorry for not enough information i posted this quickly as i had work soon. i will get back when i have more info.