Leave the primer bulb alone.

You don’t need to press the primer bulb empty before storage — and pressing it usually just floods the engine and makes first start next season harder.

The primer bulb only pushes fuel into the carburetor. It doesn’t drain anything, and it refills by suction, so you can’t actually leave it “empty.” What matters is what’s sitting in the carburetor bowl and fuel lines, not the bulb itself. That tiny rubber dome isn’t the thing that’s going to varnish up.

So here’s the practical rule: if your fuel is treated with stabilizer, run the engine for a few minutes after adding it, then shut it off and leave everything alone. That gets treated fuel into the carburetor, which is the whole point. If you’re storing longer than a few months or you’re nervous about ethanol gumming things up, either drain the tank and run the carb dry if you have a fuel shutoff valve, or just use ethanol-free fuel. But don’t go squeezing the primer bulb.

The bulb is fine, treated fuel is fine, and pressing the thing now will only guarantee you’re fighting a flooded engine later. Start it next season and go mow.