My 1987 full size blazer brakes were acting up...had to pump the brakes to stop vehicle....pump once...pump twice and the third time to stop, then brake pedal kept going to floor....I replaced the master cylinder and problem continues....could this be the booster or the rear drum brake cylinders?
It is probably the wheel cylinder. I just replaced one on my 1987 Dodge and it made a world of difference. I don't think it ever worked and was using front brakes alone. They worked so I just thought it was just how the truck worked. Did you bleed the brakes when you replaced the master cylinder?
