I have often seen fuel level sender not report because of a bad ground. If the tank is metal, try adding a temporary ground.
Matt
Matt & Mary Colie A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.
Many p-30 MHs are a basement model which on my rig has the fresh water tank in area between fuel tank and interior floor. I would need to drop tank. Did you place the dummy resistor close to the tank? The gauge is mounted to the fuel pump assembly on electric fuel pump rigs. Make, year and model of rig would help posters.