+1 on the various generator comments. This is probably the weak point -- the most things can go wrong.

Some of my experiences/observations:

Generally, storing it fueled without a weekly run of 10 minutes or so is a good way for it not to work when needed. It will not start.

Better to store it dry (no fuel). Let it run out of gas--don't fool trying to drain it. You end up causing a leak in the fuel system and may leave fuel in the carburetor, causing it not to start.

If stored for months at a time, store dry, pull the spark plug, put a few drops of motor oil in the cylinder, turn it over a couple of time to coat the inside, then replace the spark plug.

Store gasoline with a stabilizer, but use twice the maker's standard mixture recommendation--the fuel will last longer and start easier.

Many generators have a low oil cut off -- generator will not start or run if it thinks the oil is low, even if to your eye it looks ok. Keep oil on hand and keep it filled.

Change the oil at least annually.

As a last resort, when in trouble, doubt and frustration, read the instructions.