Transit Connect L4-2.0L (2010)
Fuel Pressure Sensor/Switch: Description and Operation
Fuel Rail Pressure (FRP) Sensor
ENGINE CONTROL COMPONENTS
Fuel Rail Pressure (FRP) Sensor
The FRP sensor is a diaphragm strain gauge device. The FRP sensor measures the pressure difference between the fuel rail and atmospheric pressure.
The FRP sensor nominal output varies between 0.5 and 4.5 volts, with 0.5 volts corresponding to 0 MPa (0 psi) gauge and 4.5 volts corresponding to
26 MPa (3771 psi) gauge. The sensor can read vacuums and may lower the output voltage to slightly below 0.5 volts. This condition is normal and is
usually the case after several hours of cold soak before the vehicle dome light is turned on. The fuel pump (FP) module is energized at the same time
the dome light is commanded on. A disabled or malfunctioning dome light does not affect the FP module control.
The FRP sensor is located on the fuel rail, and provides a feedback signal to indicate the fuel rail pressure to the PCM. The PCM uses the FRP signal
to command the correct injector timing and pulse width for proper fuel delivery at all speed and load conditions. The FRP sensor, along with the fuel
volume regulator (part of the fuel injection pump), form a closed loop fuel pressure control system. An electrically faulted FRP sensor results in the
deactivation of the fuel injection pump. Fuel pressure to injectors is then provided only by the FP module. When the fuel injection pump is
de-energized and the injectors are active, the fuel rail pressure is approximately 70 kPa (10 psi) lower than FP module pressure due to the pressure
drop across the fuel injection pump. Thus, if the FP module pressure is 448 kPa (65 psi), then the fuel rail pressure would be approximately 379 kPa
(55 psi) if the injectors are active.
Fuel Rail Pressure (FRP) Sensor
