The truck wasn't stopping on the rear brakes so I did the front and rears.Little better but not good.Put in a rebuilt master cylinder bench bled (no change) and ran the truck on jack stands,still doesn't stop well. Anti-lock light isn't on.Pedal will bleed down if you hold pressure on it. Is the anti-lock valve junk?If so can you bypass it? thanks

 

Assuming that the rear wheel cylinders are not leaking and the brakes are properly adjusted, the dump valve would be the logical culprit. Throw a new rear brake hose (frame to axle) at it first, it's a lot cheaper than the dump valve. Hippie had a shop machine him up a fitting that replaced the dump valve. They don't seem real troublesome, and they can be had for less than $100, so I wouldn't disable the RWAL lightly.

 

what you refer to as the dump valve is the valve in the frame up over the rear axle,right?

 

Yeah, it's somewhere back there.

 

What does the dump valve do?

 

When the truck is empty the valve is closed off a little so the brakes arn't applied heavily. When you have a load on the rear, it opens the valve more so you have more braking for the extra weight.

 

Nope, that would be the load valve on a 2nd gen. Durn overvalvers with their fancy-schmancy trucks

The dump valve on a 1st gen lets releases from the rear wheel cylinders into an accumulator to get the wheels rolling again when the CAB senses that they have locked. If it fails with the passage to the accumulator open, you get a squooshy pedal. The RWAL system on a 2nd gen works the same way.