To make pressure a good pump needs four things:
Fuel from the low pressure pump.
A control signal from the ecu.
No leaks in the injectors.
Check rotation visually.
Take the inlet hose of the HP pump off, and check that fuel flows from the hose when the ignition is turned on. (The pump only runs for a short time)
If there is no warning light from the ecu, the control signal is probably good.
To check injector leak-back take the small return pipes off the injectors, plug the return pipe, and crank the engine. If fuel flows out of the top of any of the injectors, those ones are damaged and need to be repaired.
If all these are good, the pressure control valve on the pump may have failed mechanically, or the pump may have other faults.