Brand new mower out of the box, got it together, primed, turns over but shuts right off like it's not getting gas. Is there a shut off switch or something?

SOURCE: mower won't stay running

carb is gummed up. carb cleaner is the only thing that will help, Get it at walmart, spray can usually less than $3. Comes with a wand (straw) for spraying in small holes etc. Take the air filter off and look for small holes around inside the carb intake, stick the straw right in those and shoot, WEAR goggles or classes and rubber gloves, stuff is nasty. If it still won't run you will need to do some disassemble of the carb, if it has a bowl remove it and wash everything out with the cleaner.DO NOT however get the carb cleaner on the bowls top rubber ring it will wreck it. Be careful to put the float and needle and seat back as they were. The brass screw that holds the bowl on has some tiny cross holes in it, one strand from a wire brush works great for cleaning them out. Good Luck, Chuck

SOURCE: mowers is not getting gas

Check your float ... it might be sticking in the upward position when the fuel well fully fills? This would cause the mower to run on the fuel that gets inside the line when you prime it, but since the float stuck in the upward position would close the intake line from the gas tank, your mower would die after the priming fuel is spent.
[The float is located inside the metal bowl beneath the carburator usually, and can be opened by removing a single bolt/screw in the center of the bottom of the bowl. Be careful to pay attention to how the valve-pin attached to the float is attached; usually it's just hooked on very loosely. Thouroughly clean the float, pin & inside of the bowl, then reassemble after making sure the float moves freely.] If the problem isn't solved by this, you might have an obstruction (like a leaf-cutter wasp nest) in your fuel line between the gas tank & carburator? Check the float first.

SOURCE: My Toro lawn mower starts good, but it only runs

Sounds like you need a carb cleaning. Also install some Seafoam gas additive in your gas tank to clean out the gunk that builds up. Do not use ethanol gas.

SOURCE: mower starts up after priming, runs for a few

The carb needs to be taken off and cleaned. The ethanol in gasoline absorbs water and causes problems. Disassemble carb and clean with carb cleaner.

SOURCE: my lawn mower starts easily, then shuts down. each

disassemble the carb and make sure the float valve is not sticking