My 1990 Corvette has absolutely no brake power. When the engine is running the brake pedal is still stiff and can barely be depressed just as if the engine was off. Is this the power brake booster? could it be something else? Is there any way to check?

 

Leak in brake booster vacuum circuit.

Stick your ear down near the pedal, car running, and press the pedal. You'll probably hear the hissing...