Fuel will not equalize when driving

I ran into this problem on an ‘06 with different sized tanks. Went to the dealer many times and was never solved. The smaller tank would run dry unless I stopped every so often and let it idle to fill the small one back up.

 

Check to see if the cross over fuel pipe is blocked what i'd do is seal off the tank and get some high air pressure and blow out the hose see if it fixes the problem.

 

may sound dumb BUT some Volvo's have shout off valves on the passenger tank.... my 06 does... check and see if it does and that BOTH are open all the way

 

when you can pull the pick up tube out and check it.
may have a small pin hole in it. if it does a little jb weld should fix it

 

I had this happen once a long time ago on a Ford LTL. I saw the part....it was a small diaphragm and he had bought it at our local Pete dealership. I can't remember what the heck it was called though.