Brakes

[Ricko1966]

hey guys and gals, been awhile since I've been on here! been getting back to my 87 GMC 2500 I recently replaced the brake vacuum booster, all the brakes were replaced with new parts a couple years ago and have no miles on them.I had brake pedal when the truck was not running but after I started it the pedal went to the floor!! New master Cyl.new caliipers and wheel cyls. no leaks any place. Any ideas???could the master cylinder have given up due to sitting??

Get/make plugs for the master cylinder ports. Do you have a firm pedal now? Yes,the master is okay. No the master is shot. It probably is the master in all reality. You should start a new thread though. It gets confusing when people read the first three posts from the O.P. then start reading current replies to someone who changed the subject in the middle.