What is the FRPS and where is it located? And what causes it to fail?
The FRPS is the Fuel Rail Pressure Sensor. It reports the pressure inside the fuel rail to the PCM. The PCM responds to inputs from the fuel pressure sensor and other sensors, then adjusts the fuel pressure by changing a pulse width modulated voltage supply to the fuel pump. The fuel pump either speeds up or slows down, based on what the PCM believes the engine’s fuel needs happen to be at any given time. In this way, fuel pressure across the injectors is maintained at the correct pressure. When the FRPS starts to fail (not uncommon) the result can be stalling and rough idling. Here is a photo showing its location. Many ask why the FRPS fails. Some mistakenly believe that high fuel pressure causes the failure. But it actually is caused by the rate of pressure rise. The following explanation comes from Jerry Wroblewski who helped design the SCT tuning software. He also worked for Ford, Roush and others. Special thanks to Jerry for this excellent information. First let me address your st
