I meant to refer to the "accumulator" not the regulator...sorry.
And I believe the fuel pump(s) and accumulator would reside just in front of the right rear wheel...a plastic cover protects the setup from damage, so get out your 10mm socket wrench to gain access...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car