Most later senders are a part of the tank fuel pickup. All this is removed from the tank as an assembly. If sender is separated from pickup tube the tank would (probably) have to be removed to replace it. It is difficult to remove a gas tank or at least lower it without removing or jostling the flexible fuel line. All I'm trying to say is an air leak any where in the suction line will cause poor to none fuel delivery. The only reason I brought this up is when I have sudden onset problem the best place to look is at the last change or repair. Looking at hose connections after replacing a fuel sender seems a logical place to start. (Even for one as stupid as I)

Tim White

49 Chevy panel
91 Jeep YJ