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My check engine code led to me to replacing my fuel pressure regulator on my 2004 Ford Freestar. I had the same issue a couple years ago, so I was familiar with the replacement process. After replacing it, the check engine light went off for 5-10 minutes, then came back on and the car continued acting the way it was before. That is, when stopped (and running), it will bounce a little, and after idling for about 20 seconds, it will usually just turn off.
Any ideas?
Assuming the code is P0193 - Fuel Rail Pressure (FRP) Sensor Circuit High Input.
On the fuel rail is a 4 wire pressure transducer - The Fuel Rail Pressure Sensor. This is a 5v Reference voltage sensor.
Backprobe pin 4 gray/red for ground.
Backprobe pin 2 brown/white for 5v.
Backprobe pin 1 red/pink for output 2.2v @ 30 psi.
If you don't see reference voltage on pin 2 test for reference voltage at the throttle position sensor pin 1 same color. If you don't see reference voltage there. Test pin 90 of the PCM connector for reference voltage.
If you have reference voltage at pin 90 and not at either sensor you likely have a bad splice.
Typically though with this code it's the sensor it self.
You're also going to want to confirm fuel pressure either with a scan tool or with a gauge. If fuel pressure drops off and is causing the stall check the Fuel Pump Driver Module located on the bottom of the left B pillar.
Pin 5 white is power feed from the Inertia Switch 12v
Pins 2 & 4, black & pink/black feed voltage and ground to the fuel pump
Pin 6 white/red is FPDM control and should be a variable voltage.
