That looks like the Chassis 12VDC ground or Black for the Genset. I can see the 120VAC flex (gray), the fuel hose (black) and the black flex is most likely the 12VDC POS and the control wires in the same conduit.
Does the GENSET start? It may if there is ground somewhere.
Look for a ground stud on the chassis somewhere within the perimeter of where that cable is, my guess is a loose nut that is now gone. Should be several wires at the same point and that may be why you don't have power to the outlets if the wires run back to the same point.
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