Fuel Rail Pressure Temperature (FRPT) Sensor
The FRPT sensor measures the pressure and temperature of the fuel in the fuel rail and sends these signals to the PCM. The sensor uses the intake manifold vacuum as a reference to sense the pressure difference between the fuel rail and the intake manifold. A fuel return line to the fuel tank is not used in this type of fuel system. The relationship between fuel pressure and fuel temperature is used to determine the possible presence of fuel vapor in the fuel rail. Both pressure and temperature signals are used to control the speed of the fuel pump. The speed of the fuel pump maintains fuel rail pressure by keeping fuel in its liquid state. The dynamic range of the fuel injectors increases because of the higher rail pressure, which allows the injector pulse width to decrease.