Looking to pick your brains. 2008 Ford E150, 90k mileage, no prior issues, dies going 65 on cruise. Power is good and turns over fine, but the van will only sometimes start, and then only briefly before dying back out. Code reads P0191.

I replaced pump and filter and what I believe was one of the fuses(couldn't really confirm that was my diagram).

It didn't work right away, but I randomly tried to start a little later, and it fired up and drove 5 hours one-way. But now it's broke down again, same code P0191. I honestly have never been able to hear the fuel pump kick on, and it didn't come on with the ACC when I was about to put the new pump in the tank.
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Something you might check, under the rear of the vehicle is a fuel pump driver module that controls fuel pump operation based on info from a pressure sensor on the fuel rail.

What you might check is that fuel pump driver module . They were mounted in a cross piece of the rear frame , sometimes above the spare tire mounting..
They became corroded and had to be replaced because they produced the same problems your vehicle seems to be experiencing.
If you look carefully you may see the corrosion between the back of the module and the frame cross piece. The corrosion actually eats a hole in the module and hampers the function. of the printed circuit board within..

 

Thank you for the suggestion. I looked and sure enough it was pretty corroded. Not bad enough the body was damaged, but I went ahead and replaced it anyway.

Along with that I also changed the fuel rail pressure sensor.

Neither thing worked. But then again.. When I pulled the sensor off, some fuel came out which I figured was normal, but begs the question: do I need to prime the fuel delivery system at all after putting those two parts on?
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Here are the Function description, troubleshooting chart (starting on page 4 of the .doc) and the wiring diagram. I guessed 5.4L but the wiring for the sensor of interest is the same for the 4.6.

Hope this helps