hydroboost brake issue

[lebowski]

First off, this question concerns an 86 blazer with a 6.2 i put in over the summer in replace of the original 305. On my way to work this morning my brakes (hydroboost) were acting incredibly weird. I'd seem to lose pressure, it'd build back up, lose it again, and all the while the little *waring* brake light indicator would illuminate and fade along with the problem. Alright, so I'm about a mile from work and there seems to be no assistance with the brakes. My foot alone will stop the truck at low enough speed, but the pedal is practically reaching the floor. Oddly enough the power steer is working fine. So it seems the power steering pump is ok, it's pumping anyway. So what would cause this serious brake fade? I was late for work as is, but I couldn't spot any noticeable leaks. Tonight I'll take a better look, i was just hoping to get a little direction to begin looking. Thanks for any available advice, pointers, etc..

 

[mo]

I assume you checked your fluid level?

 

[lebowski]

yeah, fluid level is fine. I drove the truck home..carefully.. and it seems that even though the pedal is traveling much further than normal towards the floor, i still have some kind of brake pressure. That caution light keeps coming on as well.