Knowing you I am assuming you have a pretty good idea of what is required. From my end not getting pressure would indicate air in the system, somewhere. Or you could have restriction with the reservoir tank flow into the master. The left front caliper is the one for the rear pedal eh.
Here's what I would do: open the rear caliper, better yet take it off first and clean it as well as the front left. With the calipers off see if you can pump clean fluid through the system, then with the calipers in place and open try to pump fluid through them one at a time. Make sure you let the pedal pop back quickly, not slowly and keeping pumping quickly until you get fluid. Once you have got that far go to your regular way of brake bleeding.