I have an '85 F-150 with power brakes. I had a caliper blow out on me and after replacing it is when this stuff started happening.

When I hit the brakes the pedal is really spongy, needs no effort, goes almost clear to the floor, and the brake light comes on. I completely bled the system and got a great pedal UNTIL I started the truck. As soon as the truck draws a vacuum on the booster, I lose almost all pedal and cannot pump them up.

I disconnected the booster and the truck actually stops BETTER with the booster unhooked. I have to pump the brakes up and put my entire leg into it to get it to stop, but at least they pump up and stop the truck. I can lock them up without the booster, but couldn't with it.

So i'm thinking the booster is shot which kinda irks me since it's only a year and a half old. Anything else it could be, or am i on the right track?

Justin

 

Sounds like a blown booster to me