A portable gasoline generator is the cheapest way to have a large back-up power source, but it comes chock-full of issues. These must never be run in a building with humans or animals in it- not even in an attached garage with the big door wide open. Matthew may have run it's course but we will see more deaths yet from improper generator use. Problems with these are fuel: today's gas does not store well and after sitting 2-3 months it may not start or run a small engine. Ethanol-free gas is best but anything will work if it's fresh. You can't just put it away and forget about it when you're done or it will not start when you need it. The easiest way out is to let it run out of fuel, add half a gallon of fresh gas with a fuel stabilizer mixed in it, start it and let it run a couple minutes, then turn it off. Do NOT run the carburetor dry- leave the gas in there and turn the fuel tap off after the engine is stopped. Every couple months or so drag it out start it, letting it run at least ten minutes with a good-sized electrical load plugged in, and add another half-gallon of fresh stabilized fuel. When the tank becomes full, drain it and start over. You need that electrical load when 'exercising' your generator as that renews the tiny bit of magnetism inside which lets the machine start making power (short version on a complex topic).
Old wisdom was to run the carb dry but with today's crappy gas doing that is guaranteed to gum up the carburetor during storage. By running it ten minutes you refresh the gas in the carb and as long as it stays wet in there gum cannot form. The engine heat will evaporate any condensation which has formed in the oil. The oil being splashed around will prevent rust on the engine internals. You can store with a dry carb if you take it of and clean it with carb cleaner, blow air through all passages, then spray WD40 on and through everything before reattaching it. You will need to renew that process annually if it's stored in an uncontrolled environment (no HVAC) and half as often if stored (with a totally empty gas tank!) inside.
I'm a Ham radio operator with over a decade's involvement with emergency and event communications, and this is how 95%+ of us store our generators which must always be ready to start and run immediately at all times. It is a system that works without fail but you cannot overlook that 2 month workout or annual carb cleaning schedule, nor can you use anything but fresh gas. The old stuff is OK to run in your car if you mix a gallon or two of it with a fill-up. Car engines have larger fuel passages less prone to clogging and the computer will compensate for any weakness in the fuel. If you put it in your lawnmower (or other small engine) it will clog that machine up so don't go there. I have also spent a few years as a professional car and motorcycle mechanic including doing some performance work so I know whereof I'm speaking.
Propane (LP gas) is a cleaner fuel and with it you only have to worry about internal rust and condensation in the oil. It stores forever as-is, but it's also harder to obtain in emergencies since everyone gets it all to cook with early in the game, and far fewer places sell it. But if you can store enough of it safely (outside of your house only again) it by far the better way to go. The downsides are bulk of an external tank, lack of an easy way to measure quantity, and it's habit of flowing low across slabs to an ignition source if it leaks.
For a permanent installation of an at-home generator it's best to seek local advice. The usual fuels are diesel and either natural or LP gas based on the local supply and weather situation.
This is just a very condensed 'primer' on generators; barely enough to get by on. There's a lot more to know about small engines and generators (they're actually alternators since they make AC and not DC) which you should know to get the best from them. And most important is safety which you can easily find for yourself. DO that before buying or operating a generator or it may be the last purchase of your life!
Phil
