If the pump got empty it's compuslory to purge it with outlet undone untill you get good flow then after it was started you must see serious activity in the tank, that's important or the pump will fail, as about bleeding the system there is a procedure with diagnistic tool but it's not so important as the air will leave the system after the ACE kicks in few times, the ''figure 8" driving is a good trick if you can do it fast