Injection Pressure Regulator (IPR)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Ford RV Cutaway, 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.
The IPR controls the injection oil pressure. An electrical signal to a solenoid creates a magnetic field which applies a variable force on a valve servo to the control the pressure. The quantity of fuel delivered to the combustion chamber is proportional to the injection control pressure.
An open circuit results in minimal oil pressure and a no-start situation. A short to ground in a circuit results in maximum oil pressure, limited by a mechanical pop-off valve to 27,580 kPa (4,000 psi).