Sorry to start a new thread, but I've searched the existing and can't find an answer.

So I have an '09 R56/N14 with 80,000 miles on the clock. I live in Cheyenne, WY at 6100ft ASL. I've had it about 3 years. A couple of years ago, I had some starting trouble in August. Just cranked over & over but wouldn't catch. Tried some troubleshooting and finally decided to take it to the dealer, because I thought it was the HPFP. They found a crack in the valve cover and replaced it. that seemed to solve the problem (fugitive air).

Then in November of '18, it started again, but it stopped doing it after a few days on its own.

In January of '19, it did it again, so I took it to the dealership and left it there with instructions to keep it until they could duplicate the problem. I told them I suspected the HPFP, because I had eliminated a lot of other stuff on my own. I had carbon blasted the engine, changed the spark plugs, new vacuum pump, changed the fuel filter, etc. Also no codes thrown.
They finally called me back a week later and told me it was the HPFP, but the warranty had expired 8 days earlier. and they wouldn't cover it. I kid you not.
After fighting with them for a few days, I gave up, and came and got my car, and told them that was the last $150 they'd ever get from me.

The problem did seem to go away again, though, so I put it off until it raised its ugly head again.

Well. here we are. So I ordered a new fuel pump (OEM, not a knockoff) and replaced it. problem was solved for a day or two. Then it started the interminable starting again. I checked the pressure at the fuel rail at start and it was reading 1.5 Mpa against a setpoint of 5.0 Mpa, so I suspected that maybe I had gotten a bad fuel pump. I called the parts dealer and they suggested changing out the fuel pressure sensor before sending the pump back. I did that and things were great again for a few days, but it's doing it again.

I should also mention that at one point I switched the windshield wiper relay and the change-over relay (Terminal 15) to make sure it wasn't a bad relay, and that didn't seem to be it either.

So I'm stumped. Does anybody have any ideas? Any help is appreciated.

 

Update 1/31/2020:

So it's cold (20) here this morning and quiet at 5AM. I thought I'd roll the dice and try to start the car again. When I got in, I listened very carefully to see if I could hear the LPFP priming and I heard -------nothing. Absolutely nothing. So does everyone agree that maybe I should be troubleshooting the low-pressure fuel pump?

Thx