93 suburban 1500 silverado 2wd 5.7 brake question

Are you getting any air at the bleeders at the wheels? Any leaks? If no air in the system and no leaks, and the rear brakes are adjusted properly then it could be the RWAL valve.

[quote:b489d1c4b1="pantognoni"]I found out that the master cylinder was empty on the back part of the res when I bought the truck which explains the dismal brale performace and long pedal. I got it home safely and filled it with brake fluid and bled the 4 brakes but still had a spongy pedal although not as bad of course as when I 1st tried the truck. I noticed a violent swirling of the fluid in the res. when applying the pedal and since the res. was fillthy with brown sludge when I first filled it I decided to just replace the M. Cylinder. I bench bled it first. I still have swirling going on in the new m.c. res. and the pedal still travels too far for my likes.What did I do wrong or is the early abs, the booster, or something else at fault? Regards.[/quote:b489d1c4b1]
If the back of the reservoir was empty, you might take a good look at the front brake hoses and calipers to make sure you don't have a leak.