I replaced the Master and Slave cylinder. I am having some issues building pressure though.

I have a question, if the bleeder screw (on the slave) is removed and the clutch is pressed in, in theory all of the fluid should run down and out until it is completely empty correct?

It is not doing this, and I can't seem to bleed the system at all.

I can remove the hard line from the master cylinder and push out a little bit of fluid but mostly it just sucks up air. Maybe it is bad or not pumping correctly?

Any help would be grateful, and yes I have searched/etc.

Thank you