Brake Issue

So I tried to find someone with the same problem as I in the forums and came up with nothing. When I go to use the brakes I find the pedal to be hard and have to practically stand on it to get the brakes to actually grab enough to slow down. What should I check for to further the prognosis of my problem. I have bled the brakes and nothing changed. Did my master cylinder go bad? If so I would like to upgrade which I figure is a newer cherokee system since mine is a 91. Any thoughts or tips will be greatly appreciated.

Do you have anti-lock brakes?

Sounds like that system has failed, if ya have it.

I think Ive had the same "problem" in my 88 XJ for sometime. Its scary. Im thinking the booster is shot but it seems to check out OK per the book.

IF the M C leaks on a single diaphgram booster...you can almost bet the diaphgram is a goner MAD XJ has a write up on the swap from single to dual diaphgram booster....

http://www.madxj.com/MADXJ/technical/TECHNICAL.htm

Hard pedal is likely to be booster. A bad master cylinder will usually give you a low pedal, or sink to the floor, and unbled brakes will be mushy. As churky notes, if your master cylinder has leaked at the back seal it may well have killed the diaphragm, or it might just be leaking anyway. Can you hear any whooshing or hissing when you apply the brakes? If you do end up needing a booster, check for seepage at the master cylinder, and replace a leaky one.

A good booster should hold vacuum for a long time. When you come out after the vehicle has sat, push the pedal before starting. Do you still feel boost? You should. If not, start the engine with your foot on the brake. The pedal should drop some. If it does not, your booster is not boosting.

I have antilock brakes, dont hear any sounds, but my pedal is pretty much the same before and after start-up. I actaully can get the brakes to slightly lock-up by standing on the pedal in the dirt now.

Yes, that's the issue then. If you search for "failed abs" or the like, you'll find lots of chit around here

Disregard my post above which applies to conventional brakes. I know zilch about ABS.