I had this exact same problem and know what your talking about. Vacuum pump never did shit despite pouring a bottle of fluid through it. I finally said fuck it and pumped the pedal by hand very very fast and many times until I got a hint of pressure. Had my son hold the pedal down and then cracked open the bleeder briefly before closing it again. Went back and forth between slave bleeder and bleeder on fender. After a long while of doing this it finally worked out. At some point you'll switch from hand pumping the loose pedal to working it by foot.