No one has asked but if you disconnected the batteries to clean them up I suspect that you've made a mistake re-wiring them OR a wire dropped down beside or behind the batteries where you can't see it so needs to be reconnected. I had that problem myself one of the wires was hanging under the floor so I didn't see or reconnect it when I first tried to rewire my new batteries. It sounds like your batteries are at lease in fair condition. If it was a fuel problem the generator wouldn't run with the engine running either. Check voltage on either side of 100 amp breaker to ground, it could be tripped or open. If voltage is over 12 volts at both sides of the breaker check it where it connects to the generator.
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