Code P0191

Hi,

I'm Dan. It appears that your fuel pressure key on, engine off, is below spec and points to a fuel pump replacement. I've attached a Ford TSB to help you with this code. Follow the steps in the attached document and you should be ok. Let us know what you find.

Thanks just did the test and I have 4.21k Ohms on it.

Still one more question.
Where is the fuel pressure temperature sensor? I know where is the pressure sensor but no idea about the temperature sensor.
Is the pressure sensor is also used for temperature?

That is correct. The fuel pressure and temperature sensors are included on the same sensor if it is equipped that way.

The wiring diagram for this engine shows that you have an injection pressure sensor and then a separate Fuel tank pressure sensor.

I attached those below.

However, it looks like your pressure sensor is ok as it is within the specified range.

So that means we need to re-evaluate why you only have 20 PSI when you turn the key on.

Based on what you have done, I suspect the pump is the issue. So even following through the testing that Dan posted earlier, if you turn the key on and don't get a minimum of 35 PSI then you need to check the wiring to the fuel pump and if is ok you need to replace the pump.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Based on the fact that the PSI is correct when the engine is running, I suspect the wiring is fine, but you just have a pump that is starting to fail.

I attached this info below and let us know what you find. Thanks

I want to do a follow up of my situation. I tried to remove the pump from inside my RV making an access door. But I broke two studs, so I had to take the fifty gallons of gasoline out and lower the fifty-five gallons tank. I repaired the studs and put a new pump.
This morning, i filled the tank and turn the key without starting the motor.
Now the pressure is near 50 PSI (at my first trial) ... before it was close to 20 PSI.
The code P0191 is no more present, and the motor still run great.
Like you wrote, my pump was falling.

I just want to thank everybody who tried to help me.

That is great that you got it figured out. Plus, we really appreciate you coming back and providing that detail as it will surely help others.

Please come back in the future if you have other questions. Thanks