The best storage procedure to do for a generator that MIGHT have to be used in a hurry is :
- Start and run up to temp
- Shut off the fuel and let the motor die
- If the gas in the tank is not fresh, empty it and fill with fresh fuel
A generator should be started and run with a load every 1-3 months and then follow the above shutdown procedure. I have been doing this religiously on my 5kW unit for years. It always starts the first or second pull and it has ALWAYS used E10 (ethanol) gas.
A quick shot of fogging oil after the fuel is shut off
(but before the engine has died) is not a bad idea.