Hey there...I have an 04 F150 4x4 Supercrew with the 5.4 in it. In the last few months I noticed every now and then it would hesitate and feel like it lost power for a brief second. Almost felt like a tranny or torque converter problem. Now there are times where it won't start. I can crank it over till the battery dies and it doesn't even attempt to start. Most of the time, when I turn the key back and try it again it fires right up., although I occasionally have to reset the key a couple of times. My check engine light just came on and I took it to Auto Zone for a reading. It came up P0191 which they told me is a fuel system problem. According to them, it is either the fuel pump, fuel filter, the fuel pressure regulator or the fuel rail pressure sensor. Unfortunately they didn't have any idea how to narrow it down. I put a brand new fuel filter on it a week or so again so I can count that one out. Has anyone else had this problem or can anyone tell me where to start? Cash is tight so I really can't afford to take it in at this point...need to fix it myself. Any help would be greatly appreciated!

 

Hi fuel pressure, low fuel pressure, fuel rail sensor, excessive resistance.
The 191 code is fuel rail pressure sensor circuit performance.
A dealer check of the FRP PID will show the fuel pressure with the motor running.
Sorry you will just be working blind unless the sensor is bad or you find a circuit problem and have some luck.

 

I popped p0191 the other day along with two TAC codes. What did you end up replacing to fix your 191 code? I have changed the fuel filter and cleaned the throttle body but still can't get it to start. Next is a TPS or FRP Sensor.