I just replace both front calipers and pads, master cylinder, and front brake lines on my 1998 Ranger (rear lines were already done). I bench bled the master cylinder before installing, bled the cylinder after installing (has bleeder screw on it), bled the entire system and get solid streams of fluid out, but when I start the truck, the pedal goes straight to the floor, it's not even spongy, just straight down. I thought it was a faulty new master cylinder so I replaced it again and repeated the whole process and I have the same results. This is not that difficult, but I am totally at a loss. I have no leaks anywhere either. Any suggestions?? Thank you!

 

also, I have no brake warning lights on. I just "bench bled" again on the truck (using the pedal instead of a screwdriver) and get no air whatsoever in the lines from the outlets back up to the reservoir.

 

Could my vacuum brake booster have gone bad? without the engine running, I can pump the pedal and the pedal will return, but when I start the engine, the pedal goes down and won't return, I have to pull it up with my foot. After I shut the engine off, I pushed down on the pedal, heard the booster, pedal didn't return, pulled up the pedal, pushed the pedal down again and the pedal started returning.

 

i dont think its your booster, but did you do an ABS service bleed? any time you replace the master cylinder you are supposed to service bleed the ABS system.

as far as i know, only the ford IDS service computer can do it

 

your calipers on the right sides? you sound like me when i made this tiny mistake, pedal goes straight to the floor, yet you think the system is bled because you get a solid stream of brake fluid at the bleeder on the caliper. is the bleeder pointed down? if so then you have an air pocket in the upper piston. switch sides so the bleeders point up. rebleed. hope this helps.