ok so me and a buddy did his brakes on his blazer i belive it is a 2000.so everything is done and now we have this problem..when you apply the brake pedal its really hard and frim like its supposed to be but its does not stop...so we bleed the brakes and still nothing?i did notice this loud air sound/noise coming from the inside of the cab as i pressed the brakes down ..pedal gets hard really fast and all i hear a pppsssshhhh noise and the truck barely stops...its also killing the engine when the brakes area applied we only did the fronts not the rear ..the rears are drum ..any more info needed let me know thanks for any help thoughts or ideas...

 

Everything you mention points to the vacuum diaphram in the power brake booster being bad - except for the hard pedal. When the booster goes bad, it creates a vacuum leak when you press the pedalwhich explains the noise and engine wanting to die, but the pedal will usually just drop to the floor. I'm not real up to date on newer braking systems, but I don't believe there is anything vacuum related to the proportioning valve (which fits a hard pedal no brakes scenario, but not the vacuum leak) or the abs controller.

 

This actually sounds like a leaking brake booster. If the booster is leaking vacuum the pedal will be hard and high. If it works properly it will assist foot pressure and the pedal will go down further.
If you have a fluid leak, air in the system or a failed master cylinder, then the brake pedal may go to the floor.

Locate the vacuum leak! It's either the vacuum hose connection at the booster or the booster itself.

 

Yahthat definetly sound like avacum system issue, if the system were fine with the truck off you should be able to pump 3 timeswithvacum assist.Then by about the 4th or almost 5th it would be like your pedal is right now which is manual brakes.I would definetly say fix the leak before driving more unless you have legs like the hulk.

 

allright i will look for a leak and see what i can find...i will post up again with more info..thanks for the help