That's why you don't leave old fuel in such an expensive and important device. You either stabilize the fuel to prevent gumming or you disconnect the fuel line from the tank and let the motor run its self out of fuel. No need for special equipment.
Yeah but with stand by units it's not a plug and go situation. They require electrical panel installation, transfer switches, raceways and conduit etc. And they still need oil changes every 8 hours just like portable gens.