EFI will normally hold pressure better than this, due to the sprung loaded valve, that is the pressure reg closing the flow off, but so long as it is working and maintaining under load, the correct fuel pressure should be ok.
If the volt gauge has been wired to the number 1 position of the ignition switch(accessory) then it will drop out in the start position as the start position cuts power to accessory position normally, rewiring to number 2 pos will make it run 100% of the time but I wouldn't bother.
tabetha