I have seen a few request for replacing fuel pumps. First check the fuel pump by turning key on and pressing FP button. Remove black plastic cover on starboard side aft of fuel rail. Under cap is a phillips screw. Also use a vise grips on the return line to the tank. That is the line between the pumps. If the fuel pump is working the screw will raise about 1/8 inch and stay up. Next if screw does not come up Unplug one connector on fuel plug. Test again then connect and test the other pump.
Hitting the pumps with a hammer will loosen a pump that has seized.
Testing the voltage at the pump should only be 1 volt less then battery voltage. If it is more look for a bad ground. Add a ground wire from the block to the white wire on the pump.
I would have a spare lower fuel pump,
2310150030 PUMP FUEL SECONDARY NO2 BOTTOM 61 units available
Capt Rick