My Generac generator will start but will only run for about 5 seconds and then it stalls. It won't start when I try again. If I try starting it again, it will again run for about 5 seconds and stall. I've owned it for about 9 years and have NEVER had a problem starting this before. I ran it for at least a couple of hours last December to run it out of fuel. I then filled it with fuel again, added Stabil and ran it for a bit before putting it away. Any ideas?

You don't specify the model so these are general:

Do you have the low oil sensor? It may be cutting out the engine, how's the oil level?

Do you have a fuel shut off valve under the tank? Is it wide open?

If both of these check out then I suspect your carburetor needs cleaning. You can start by pulling the float bowl and making sure it is clean. Make sure the float is moving freely as well. Let some gas through the line to make sure it is not blocked.

If that doesn't work the carb will need to be rebuilt. If you do this, note the position of every linkage on the carb - take pictures!

I've had poor luck with Stabil over the past few years on my generators and snow blowers. I think it is just the new gas. Gave up and converted the generators to propane, the snowblowers get run once a month, even in July and August. No trouble since.