brake problems!

[thedriftbandit]

Hey guys, just got my s14 out after winter. Having a weird brake issue. The pedal goes to the floor, brakes barely engage, and the motor labors if I pump the brakes. I bleed them when I replaced the brakes over the winter and will be bleeding them out tomorrow again, but I'm not sure why the motor would labor... any thoughts or comments are appreciated. Could this be the master cylinder?

Thanks

[thedriftbandit]

Also the pedal stiffens up like normal brakes should feel when the car is not running (???) No leaks as of yet.

[dbeiler]

The engine laboring sounds like a vacuum leak. I would suspect the brake booster or the check valve. If you have one those autoparts store vacuum pump/gauges handy, you can vacuum test the brake booster and the booster check valve. Perhaps the valve is stuck open.