W 3500 L4-5.2L DSL Turbo (2006)
Fuel Pressure Regulator: Description and Operation
Fuel Rail Pressure (FRP) Regulator
The Fuel rail pressure (FRP) regulator is installed to the fuel supply pump and controls the suction fuel quantity into the fuel pump. The FRP regulator is
fully opened in the normal state and larger drive current results in smaller opening. The engine control module (ECM) calculates desired fuel rail
pressure and fuel flow rate and compares the calculated desired fuel rail pressure to the actual value to determine the FRP regulator position. When the
actual fuel rail pressure is higher than the desired value, the FRP regulator is closed to decease the flow rate.
