My brake pedal sinks to the floor. If I pump the brakes it holds pressure fairly well. when I release the brake and press it again while driving, it sinks to the floor again. I bled the Master cylinder on the sami, and bled the brakes according to the manual, and I still have the prob. I bought a used MC and installed and still have the problem. Unless I didn't bleed enough I'm thinking it's another bad master cylinder.... Imput?