I just changed all four rotors and pads on all wheels. I tried to pump the brakes and the pedal goes all the way to the floor. I pumped and bled the system seveal times with no success to firm up the pedal even the slightest bit. Res. is topped off with new fluid. When car is off, i can build slight pressure but after 1/2 way down the pedal have a little tension but then release to the floor. When engine is on there is no pressure at all.

I have pumped the breaks with short strokes and can build a little but soon after it releases and goes to the floor? Any Help?

 

What kind of car, what year etc etc.

 

Sorry about that. X-Type 3.0 2003.

 

You probably have air in the brake lines. Recommend that you FLUSH, not merely bleed, all of the brake fluid with fresh fluid. If - and only if - after flushing all of the fluid and assuring that there is no air in the lines, you still have a problem, then you can start looking into problems at the master cylinder first and then elsewhere in the system.

If you've never flushed the fluid before, you might benefit from reading about some tools that could help. I wrote this page with an eye towards my other/older vehicles, but the principles apply to your Jag nonetheless:

Bleeding or Flushing Brake and Clutch Hydraulics