a solenoid valve which regulates the pressure in a pressurized fuel injection system includes a body containing a needle that is pressed by an electromagnet including a coil and a magnetic core . the core has a cavity that is in fluid communication via an internal channel with a counterbore in the body into which the needle protrudes and into which fuel flows during use . the core also has a restriction which restricts the fluid communication and which attenuates pressure waves propagating in the fuel to prevent the waves from moving the core .