So recently I di the chevy 63 swap on my truck. It's an 86 pickup dlx with the 22re auto. While I was doing the swap I pulled the rear axle to replace the hard brake lines and paint it.
the entire truck has all new hard lines, all new rubber lines, all new fittings, complete drum rebuild with new wheel cylinders, new calipers, pads, rotors for the front, and a new master.
before I started this project I had normal brake operations.
After running new lines and bleeding them properly I had working brakes until i started the truck and tried to drive it. The pedal built pressure then all of a sudden went to the floor. I checked everywhere for leaks and found none. I'm getting clear brake fluid with no air coming In anywhere. Drums are adjusted correctly. The only thing that i noticed is the brake warning light is on, and when I press the brakes while the truck is on it starts to bog out a little.
that leads me to assume it's a vacuum leak weather it be the booster or the lines. How can I check the lines to ensure they're okay and does this sound like the booster is bad? Everything else in the system is less than 6 months old. Snd my rig is a trail only rig si I've driven it maybe twice.
Sorry for the long read.

 

Never mind. I got it figured out. The check valve between the vacuum lines was bad. Swapped that and now I've got full breaking power.

 

Thanks for sharing your finding/solution. Others would just leave and keep quiet.