No power to the EFI number two fuse?

Okay, the ECU B having power to one side indicates the fuse is bad, even if it looks okay. As for the EFI #2 fuse, it receives power from the ECM 1 fuse through the EFI relay. I suspect that the control signal that turns that relay on gets its power through the ECU and fuse B. I would start by determining what the issue with ECU fuse B and see if that allows the relay to activate and get the EFI 2 fuse to power up.
With the power on just one blade, I would start there.