I have a 1998 blazer and a couple days ago my brakes started going all the way to the floor. I can still stop but it feels like there is no help from the booster. There are no fluid leaks and when the truck is off i can pump the brakes and they have pressure, then once I turn it on they go to the floor. I have no idea what the problem could be?

 

I've read about this happening before, I'll look around and see if I can find the thread and I'll link it to you, that's if someone doesn't answer before I can find it. Btw, did you replace any parts to the brake system by chance?

 

What happens when you stomp on the pedal really hard when the truck is running, does it get stiff quick? Sounds almost like the master cylinder being the problem.

 

From my experience it sounds like a master cylinder.

 

When I stomp on it the first time it feels stiff then proceeds to go to the floor. After that it feels like it has a little pressure but still goes all the way down. Is the master cylinder a pretty easy fix?

 

Yes, it is fairly straightforward and not challenging. I hate to use the word easy... One of the biggest keys is to make sure and bench bleed the master cylinder first to get all of the air out of that. Removing the old one just disconnect the two nuts holding it in and the brake lines (with a flare wrench). Be careful not to drip brake fluid all over the place, it likes to dissolve paint and plastics etc... Installation opposite of removal. Then you will want to bleed the brakes, the gravity method works well for these vehicles. I would bleed them until you had fresh fluid coming out at each wheel and or course no air coming with it. You may have to bleed the ABS system too with a capable scan tool and then gravity bleed again.

Hope that helps!