So just to add to the confusion....just spoke with my mechanic and we left vehicle parked indoors in heated shop overnight. This morning went to start, fuel pressure there and started right up no issues at all. It is really strange seems to be temp related at most times, no start or fuel pressure in cold weather. Brand new batter btw.:dunno::dunno:

We moved it outside to let it sit and try it again.

Only diagram that I have been able to find in Bentley for a N62 engine is ELE 117.

Don't know why you can get software to power up the fuel pump but can't get the key to prime the fuel pump.

The prime is normally controlled by the DME. Have you scanned the DME for error codes?

Yes that is the part which I am confused about. Also this morning, absolutely fine.

Yes we did scan, zero error codes. I am at a loss......the change in climate is the part that is really confusing things.

Condensation frozen up at sub-zero environment and clog the fuel filter, possibly affecting the fuel pressure regulator.

Just my 2 cents. Good Luck!

Mmmm good point, still does not explain no priming of fuel pump.

Cracks or a bad solder joint in the circuit board in one of the module that opens up when the temperature change is what comes to my mind.

That could be a possibility I guess. I will try a few things and report back, any further suggestions would be appreciated!

Priming problem you mean no fuel pump engagement while key at ON, or priming with no pressure at fuel rail? If latter, fuel filter will explain it.

When turning key to on position, no pressure at all at fuel rail and pump does not kick in at all.

Relay K96 controls power to the fuel pump. Relay K96 location can be found on page Fuel Injection 130-7 of the Bentley Manual. The relay is located on a panel located above the glove box. You could have a faulty relay that is affected by cold weather.