Fuel metering valve Fuel measurement valve
Fuel pressure regulators, also known as suction control valves or IMV valves, help maintain fuel pressure in the fuel injection system. If the fuel injection system requires more fuel pressure, the fuel pressure regulator releases more fuel into the engine. Because that's how the fuel gets into the injectors. The fuel pump completely blocks the passage to the fuel tank, it presses too much fuel into the injectors, causing them to fail and you'll end up needing another car service.
As you can see, the fuel pressure regulator plays a vital role in a common rail diesel system.