Pulling that old portable generator out of storage to use during a weather-related blackout just to find that it isn't working is a problem. When you're stuck in the backwoods and can't get to town or call an electrician, you'll need to do some quick assessments to see what's wrong.
What To Check First
When your generator won't start, it's time to break out your DIY hat:
Check the gas. The shelf life of gas isn't as long as you might think. It's about three months. If your generator has been stored in the garage for longer than that without being started, the gas is likely bad. When bad gas goes through the carburetor, it gunks it up and the carburetor will need cleaned. You'll have to siphon it out and replace it and see if your generator starts. Never add gas to your generator while it is running.
Check the gas vent hole. If it's clogged, the gas can't get from the tank to the carburetor. Simply unclog it.
Check your spark plugs. You have to get that electrical spark to ignite the generator, whether it's an electric or gas generator. If you look at the bottom of your spark plugs, you will see an electrode. This must be kept clean so that your spark plugs produce that ignition spark. You should replace your spark plugs once a season or after about 25 hours of use, according to Briggs and Stratton FAQs. Always keep extra spark plugs on hand.
Check the fuel lines and the fuel filter. Replace the fuel lines if they are cracked or clogged. Again, it's best to have extras on hand as well as an extra fuel filter.
If your gas is good, the vent hole is not clogged and the spark plugs are new and clean, you may have flooded the engine when you tried to start your generator. If you had your generator on full choke and pulled the start cord or pushed the start button multiple times, and your generator won't turn over, the engine's carburetor is likely overrun with gas and will need cleaned out. Sometimes you an let the generator rest for a while and then it will restart, but not always.
If you've checked all you can check on your own, made what repairs you can make, and still can't get the generator to hum, you likely have a mechanical problem--maybe it's the gearbox or motor that needs repaired or replaced. Contact a technician, like Hackworth Electric Motors, Inc., for more help.