No brakes need suggestions

[Sly8795]

I have a 90 Jeep Cherokee and my brakes have been horrible since I bought it three years ago. I replaced the front brakes not the rears but the most notable reason the brakes may not work well is that there is a hissing sound when I hit the brakes. Is this a bad brake booster? Is there a way to check if its getting enough vacuum to work the brakes. I also replaced the master cylinder already as well. Any suggestions on where to start would be great. Thanks

 

[mud4feet]

I'm far, far, far from an expert, but I think you're on the right track thinking "booster". That's the only thing I can think of that would hiss. Hopefully, someone on here will either confirm me or correct me. Good luck.

 

[88Wrangles]

Have someone listen under the hood while you hit the brakes and see where it's coming from.