I have a 88 GTA with an automatic 305, & it has the 1LE brakes. A few days ago the brakes stoped working, the pedal goes in all the way to the floor & it barley stops the car. First thing I did was to check the fluid thinking I had a leak, but is all there. That makes me think that Im having problems with the master cylinder.
Can someone with more experience point me in the right direction. where should I start looking for problems & how?

 

Was the fluid in the cilindar really low if so maybe you have an air bubble in the brake line id also look for cracks in the line by all the wheels.

also if you pump the breaks can u build up pressure?

 

I havnt touched the system in more than 3 years, so I dont see why I would have air in the lines now. There is no leaks, I have stainless steel lines, & the fluid level is fine. & there is no pressure, even If I pump them.

 

sometimes the Master Cylinder can leak through the rear seal into the brake booster, where you can't see it. if there are no apparent leaks, i'd pull just the two bolts that hold the master cylinder to the booster and see if its wet in the back or not, if so, deffinately a problem, but a suspect none the less.