I have a '99, non-ABS accord. I was driving today, everything was going fine... the 3rd time I tried to stop, it wouldnt. The brake would go all the way to the floor, probably only 10% braking power to the wheels. It felt like I was sliding on ice. I dont see any leaking fluids (though its raining and I might not see it). The pads/rotors are fine, I also dont hear any abnormal noises.

Is this a common issue? I'm hoping I can diagnose it before I take it into a shop.

 

Sounds like you have air in the system.

 

There are places that fluid will leak and you may no see it. If you have drum brakes for example. IT could be a failed seal in there, possibly a caliper piston seal, or air in the system. However air means you have a leak if they were working before and you haven't opened up the system.

Another problem is if the piston seals fail in the master cylinder then fluid will leak back and forth rather than pressurize the hydraulic system.

 

Just an update, I added some fluid and it is leaking about 2 feet in front of the left rear wheel. Cant really see anything, hoping its just a hose.

 

Probably a hose or a metal line. If you replace it, you will need to bleed all 4 wheels just to be sure that there is no air.