Weird brake issue
 

Ok i had to replace the brake lines in the rear of the truck and the main line going to the rear.

First i adjusted the rear shoes.
Then i bled the master cylinder.
Then I bled all the brakes starting with rear passenger wheel.
Then driver rear wheel.
Then did the rear splitter.
Then Did Rears Again.
Then did the Front calipers

My issue is when the truck isnt running i have firm pedal.
When truck runs i have almost nothing for brake.
The fronts grab but cant seem to get the rear to.

My question is wht in the heck can be causing this issue?

Im tired of fighting with brakes on this thing been almost three mths of brake issues from one thing to another.

did you do the pump and hold the brake pedal method or just gravity bleed.

i had the same issue a few months back. ive always had great luck with gravity bleeding but for some reason it didnt do the trick, guess a air bubble was rolling around in there

i have replaced both calipers and replaced rear wheel cylinder. i have also removed abs pump and gone back to standard setup. reason for removing abs pump was main line runing from abs pump to rear was stripped out clean and couldnt be retaped. i bled by pump and hold.

My bad you start furtherst away. But you still ony should blead the wheel cylinders and calipers. When you open the line you are introducing air into the system. If you are sure you got all the air out the only thing else it could be is the weak master cylinder , to big of line to the rear, or you got a leak.

could it be the vacum booster? when i disconnected the vacum line to it i can hear a big rush of air from it.

no i dont think so when a booster goes bad you pedal is hard as a rock

Yeah the booster will just make it so you have no power brakes not effect your pedal height