First post on in a while. I'm back in the Ford truck owners club with a 1990 F-250 HD, 5.8L, 2WD. I swapped out my front brake pads today and had a good pedal after changing out the pads and getting the pads adjusted (pumping a few times to take up the slack). I decided it would be a good time to flush out my old brake fluid with a vacuum bleeder. I have done at least 50 brake jobs so I'm not really new to doing this, but haven't done one on a Ford of this vintage.

I started with the rear brake cylinders, everything normal there. Then I moved on to bleed the RABS valve on the frame rail. When I opened the bleeder nothing came out at all. Took the bleeder out and still nothing. So I moved on and bled the front brakes. When I got in the truck, the pedal felt okay with the car off but a bit squishy with when running. I ran the truck on the lift with the wheels off the ground. If I let the wheels get up to speed and brake the pedal would pretty much go to the floor. So it seemed to be worse when the brakes wheels were moving.

Thought that maybe I was having trouble with the RABS so I disconnected it and bled everything again and still no change. If I crack the line on either side of the RABS valve fluid will drip out but still absolutely nothing from the bleeder screw even with it completely removed. I even tried blowing it out with an air nozzle and still nothing.

Not sure what is going on but the truck is undrivable now. The only thing I can think of is that maybe I destroyed the seal in the master cylinder by pushing the pedal to the floor after replacing the pads and trying to get them adjusted. But that wouldn't explain the issue with the RABS valve. If anybody has any advice that would be greatly appreciated. Thanks