Fuel tank problem

2009 international transtar 6 wheel tracktor.
ISM Cummins alison auto,
Only drawing fuel from drivers side tank passenger side is full?
I found a clogged vent and cleared it and verified its clear by blowing into hose and hearing it in the tank.
I can't see any valves on it to isolate the tank so I'm stumped...

 

Thanks for your reply after doing some diagnosis I found the fuse for the transfer pump to be missing so I replaced it and ots working.
This truck will be used for the Shriners and we only need 1 tank. It will only do 3-5 thousand miles a year if I run down the passenger tank and pull the fuse will I be ok?
It was only drawing on the drivers side before I put the fuse in. Thanks in advance

 

Thank you Sir