On the B-17 you could transfer fuel but it was a ponderous process and move the fuel at a low rate.  The airplane is setup with a fuel tank for each engine located in the wing behind the engines (the inboards #2,#3 actually have to separate cells plumbed as one).  There was no means to transfer fuel within the same wing, example #1 to #2.  To go from 1 to 2 you first have to pump the fuel from 1 to either 3 or 4 then pump it back across the airplane to 2.  Quite time consuming.  There was a single pump used to do the transfer, any failure of that pump and you weren't moving any fuel.
The B-24 had a fuel manifold over the wing in the midsection.  The Liberator I flew had been modified with a modern fuel system so I don't know the details of the Libs transfer system.  As I understand the engineer would manually plug/unplug fuel lines on the manifold to move fuel as needed, and again done with a low volume pump so very time consuming.
Doubtful the fighters had a means to transfer fuel.  Normally just a selector to determine which tank fuel is drawn from.