Fuel pump relay is under the dog house. It is on the left side chassis brace about middle of dog house opening.
You could be correct that the converter does not charge chassis battery. My battery control center does not have the small circuit board that plugs into the fuse panel in the battery control center to enable charing chassis battery. Common for our era not to have charge circuit.
Doubt that is problem! You should be able to hear pump running. It only operates when ignition is on and EMC sends signal for about 10 seconds to relay.
I would start pulling fuse to locate load. Start by using battery disconnect to shut down Fleetwood items that operate through the battery control center.
