2013 freightliner Cascadia dd13

I took my truck in the shop because it was taking diesel out if passenger tank so it would shut off because it would run out of fuel only using the passenger tank and not using both tanks. I took it to the shop Tuesday and they told me to lower the fuel so they can work on it. While the trucks as there I told them to change my fuel filters oil and grease it up . Noe my truck wont turn on just cranks . Only way it turns on is if u spray it with starter fluid. They told me air getting in the fuel system but can’t find where its coming from. My truck never had that problem. I took it out they shop Friday and took it to a different shop. Any ideas on what can it be? First shop changed the rings and just got tired messing with it telling me to take the truck and hopefully when they change the valves from the tanks that fixes the starting problem to but it sounds like they dont even know what they did to my truck causing it not to start . I need help hope you guys can help me out