I'm having the stalling, chugging issues on my 2007 XC90 3.2, 165k miles, many have talked of on other threads...I see good guidance on how to replace a PEM that's located inside the wheel well, but nothing about where it is if not found there.
I have taken the inner wheel well liner out of the right rear wheel well and there is nothing there.
Also, I have checked with an OBD reader and the car does lose fuel pressure as it starts to die, as we all know...wondering if it is worth changing the pressure sensor? Does the pressure sensor send a signal to the pump to demand more fuel? My fuel pressure is constantly fluctuating between 45 and 15 psi, just rising and falling at idle....to me it sounds like the PEM...does that sound right?
Any help appreciated.

 

I have also removed the rear cargo area to where the battery is located and don't see anything there either....is it under one of the seats?

 

Found it under the right rear passenger seat, second row.

 

Under the very back passenger seat? I do not see it there, did you mean the middle row seat?

 

I would use a scan tool and compare what the fuel pressure sensor is reporting to the ecu with what a mechanical gauge says. For what its worth - the only Pems I've seen bad were the ones mounted outside of the car and they were damaged from corrosion. Diagnose first, then replace what you can logically prove or reasonably deduce is the part (if needed) causing the problem.