1987 vert. Brakes got spongy. Car is drivable and stops fine, but not comfortably. . When running I cam pump a couple times and get an acceptable pedal resistance, but not for long. If I bleed (I've done it 4 times) I will get a full solid pedal but when started they return to spongy. Car is in good shape and master cylinder and booster seem normal. Still the problem persist. There are no indications that the ABS is failing. I hate just throwing parts at it. Anybody know a way to determine the problem? TIA

 

If you have bled the system and are confident that you got all of the air out most likely the master cylinder is bad.

 

I agree w/ 74HARLEY.

 

Y'all called it. Replaced the Master cylinder and bled again. Much better but not yet perfect. I need to bleed again. Didn't get done as my pumper had to go shopping lol

 

If the car has power brakes, see how the brakes feel with the engine running if you haven't already done that.