About 3 weeks ago while i was driving I went to press on the brake pedal and it was hard as a rock!! I managed to make it home and did some research. I ended up replacing the one way valve on the booster with no result of improvement. I then tried replacing the booster still nothing and finally today the vacuum pump!! And I still have a stiff pedal although its a very little bit better. Tomorrow I'm going to try just running a single piece of hose from the vac pump to the booster. The new booster I noticed after replacing the vac pump is making a hissing sound when I press on the pedal. Does this mean that the new booster could possibly be bad. What are some other ideas to check on? I don't want to keep throwing money into this pit as I'm in the process of buying a house!!

Thanks for the help guys
Bob

P.S. it is my 94 f250 7.3 IDI auto 4x4 with cruise.

 

I ran a hose from vacuum pump directly to the power booster and brakes seem to work quite a bit better but the pedal did get a little stiff and quickly recovered itself. It did make a hissing sound again as well. Do you think the new power booster could be defective?

Thanks

Bob

 

Sounds like the new booster is a dud.. hopefully you can get a new one under warranty.