87 fc n/a brake problems. dont know were to start
 

I bought a 87 na fc. Dont know witch model it is?(has roll up windows. has sunroof tho not much else.
For being 26 yrs old it runs and drives great and has no rust and minimal problems. I have pretty much drove it back and forth to work everyday and started body work on it but havent got under the hood yet.

On my way to work today the brakes just quit. They go all the way to the floor and once ther it barley applies brake. If I then pump them up from the floor i get pressure at the pedal but now i cant get any brake power unless i release the brake and slam it to the floor again.

no leaks under the car or under the hood. the cylinder is full and the brake lines all look ok.

Im going to bleed it properly this weekend of course but why would they work fine then this happen with no leaks or problems in the system.

Were would you start?

First of all do not Drive the car.
Secondly is too get the car up and check EVERYTHING.

It sounds like you busted a line and really that should show with fluid leakage.

State how many LUGS the wheels have as the 4 lug and five lug brakes are a little different.

Its 5 lug. I sell cars at a dealership so I had it up on the rack already and I couldn't see any leaking from any of the brake lines at the wheel and the res is full with no fluid loss since this started.
It looks like it was garaged and babied for years cuz there is not a spot of rust under or the paint and it's from michigan! so all the lines and stuff at least look good.

Booster
 

It could be the power brake booster. In my haynes manual, it says to check for normal operation, put your foot on the brake pedal and hold it down while you start the car. If the pedal lowers slightly, operation is fine. The master cylinder's inner seals could've failed as well. It's worth checking

Sounds like your master cylinder has failed, it's not leaking out, but the seals aren't holding and the piston isn't creating pressure. If you cant find any leaks I'd definitely start with a master cylinder.

i think ^this is the most likely scenario.