P0191 is fuel pressure sensor circuit.

Quesion is what is the function of this sensor within the engine ECU?
Does the fuel pump vary its speed depending on demand rather than older systems wher the fuel pressure is increased on the rail via vacum?
Any help anyone

Thanks

Chris

 

Chris,

You need to identify your vehicle by year, engine, and transmission. There are differences and we aren't psychic.

Welcome!

Steve

 

Sorry you are right

The vehicle is a F150 Lariat year 2004 5.4 V8 Petrol 4x4.

The code only appears every once in a while.

One point worth mentioning is that the vehicle is converted using a sequential LPG conversion and is running fine both petrol and gas.
The code mainly appears on LPG and I am assuming that the fuel pump speed is variable to engine load / demand. The gas system is slave but does not tap into fuel pump wiring as the pump needs to run all the time
I am trying to understand the above code to see if the logic used by the petrol ECM controls pump speed or not?

Thanks in advance

Chris