No fuel because it doesn't open. Its a solenoid should be open or closed. Don't know if might intermittent fail for some reason or other????
For a DS pump the fuel shut off is a fail safe it doesn't actually cut the engine off. The ECM does that by cutting off the fuel metering solenoid power via the PMD/FSD. With no power to the fuel metering solenoid it won't build pressure to the injectors it just recirculates in the IP.
Its my understanding the fuel shut off solenoid does cut off the fuel in a run away situation when the PMD/FSD shorts to keep power to the fuel metering solenoid and thus injections going at full shots.
Only if the pump mechanically failed where key off removing power didn't stop an engine runaway is where the Fuel shut off valve would help. The computer doesn't use it to stop runaway - ever. In depth linked here.
If it is leaking you need to replace it. Wiggle test connector with engine running. Any codes? An open solenoid should code. Otherwise look for other fuel restrictions like a plugged tank sock, filter, kinked hose, etc. PMD issues including grounds and extension harness?