What is probably happening is the cannister is syphoning fuel into it from the tank. They might have forgotten to connect the 1/8" syphon line.
Here is a pic of the pump pulled out from the cannister is sits in.
See the small black hose. That is a separate bleed off the top of the fuel pump that acts as a venturi to syphon fuel from the tank into the fuel pump cannister.
So if this is not working the actual bottom of the fuel pump is about 3/4" off the bottom of the fuel tank. That'* a lot of fuel left.