[bluebowtie67]

2000 Silverado 1500, 4x4, 5.3L, (I assume it has ABS)
My dad recently bought this pickup and was told upfront by the previous owner that it 'probably needed bled' because they had done some brake work or something.. very vague.
The brake pedal was very mushy and basically no resistance until the very end of the throw, when there was a little pressure to stop the truck. Not ideal by any means, but alright for putting around our farm, etc.
We were going to bleed the brakes and for starters the fluid in the reservoir was dark and disgusting- separations between brake fluid and dark slime- didn't really look like any standing water but not sure if that would separate. So we sucked that fluid out and cleaned the reservoir out. Took the two lines off and ran some fluid through as well. Hooked the lines back up, filled the reservoir and started bleeding, RR, RL, FR, FL. All the same: Pedal was pumped up (which after reading on here I realize is not the proper way, which we'll correct next time) and then cracked the lines. The pedal would never get any real 'feeling' in it- pretty much to the floor each time- and no fluid would squirt out of any bleeder. They were, however, all identical in that with the bleeder open, fluid would start seeping out- about a drop every few seconds.
It seems that there is no pressure being built up at all. The fluid level has never been an issue before, and there seem to be no leaks. Haven't thoroughly inspected for leaks, but during our bleeding there was no fluid shooting out of anywhere so that doesn't seem very suspect.
I've read all the other posts I could find about this and didn't see anything quite like this, with no pressure at all while pumping. I'm not new pickup savvy, so please give me any input. I replaced my 67 C10 master cylinder for basically the same problem and it worked, but I realize the 33 year difference. Thanks for any help everyone!