Have an intermittent issue and searched for some info and it appears the HP fuel pump on my '07 MCS is acting up. Have a service appt scheduled at the dealer since there was that notice for the fuel pump extending warranty to 10y/120K. I'm at 7y/102K right now.

CEL came on and engine stumbled, I stopped and started the engine and it ran OK but did it again and CEL on the speedometer came on full. Checked the code later with my GoPoint and it was P3091, which indicates "P3091 - Fuel Rail Pressure Pressure-Rate-Controlled, fallen below minimum pressure" Next day, it's fine, but it did come back. I had left the GoPoint in, so I was able to check the fuel rail pressure, and it was running at 250. Today, at idle with no CEL, it runs at 1400, up to 2500 during driving.

The GoPoint reports that as inHg, but it's gotta actually be mmHg because other sources report 5 bar pressure as normal to start the car, and 250/1400/2500 inHg converts to 8.4/47/84 bar respectively.

Do these numbers make sense, and do you think the GoPoint is just expecting the value to be inHg and the values are really mmHg?

(Pretty sure the numbers point to a fuel pump issue, just wondering what's normal for idle/driving)