The mounting bolts for the generator would typically be steel.
When in an RV, the fuel pump gets its ground from the chassis ground of the RV via the black wire bolted to the generator chassis.
If you place your hand on the pump when it is operating, you can feel the vibration.
If you suspect your ground then clip wire to the ground wire of the fuel pump and the other end to the chassis of the generator and then try to start the generator. While it is cranking the pump should operate.
If it doesn't pump at all then get a multimeter and see if you can measure the voltage from the hot wire of the pump to its ground. You should read the same as you do across your COACH battery terminals, around 13.5-VDC, while the Gen is cranking.