Generally, the OVP affects hot starting only, and once started, starts up fine (i.e. not sputtering, fuel smell, etc).
Any dash indicator lights on as the problem worsened (ABS maybe)? That would point to the OVP. SO would rough idling, but that may be just a blown fuse on top of the OVP.
The fuel smell has me leaning towards the fuel pressure regulator.
Although if the OVP is original, it is due for a replacement as the original is defective for the hard starting symptoms...
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