My lawnboy model 10313 has to be primed every time I want to start is. Is this normal? If not what could be the problem.

Old fuel? Check to see if the spark plug is getting spark. prime the carburetor to see if you have a fuel problem. does it have fuel in it? if it starts back up after it cools off change the spark plug. Go through this guide and see if that helps? https://canberradiamondblade.com.au/lawnmower-troubleshooting-guide/

check to see if the spark plug is getting spark. prime the carburetor to see if you have a fuel problem. does it have fuel in it? if it starts back up after it cools off change the spark plug

wherever it runs the best.

I am assuming you put more gas back in it. With that said you may have to basically "prime the pump" Take off the hoses one by one that run to the carb and make sure gas is dripping out of them all the way to the carb. After that a shot of starting fluid while it is being started should get you going again.

clogged fuel line. the choke restricts air flow if it runs fine choked it is probably getting too much air to run properly. those 2 seconds it is most likely running off a surplus of fuel from priming or something of that sort.

Check fuel lines and fuel filter for obstructions. I reccomend replacing fuel filter also. If this does not help is may be a fuel issue in the carburetor.

Clean carb....

http://www.briggsandstratton.com/maint_repair/manual_and_more/

Save this is your computer. Lots of info here.

The engine is starving for fuel, that is why it will keep running while you force the fuel to the engine with the primer button. At this point, the carb will have to be removed,disassembled and cleaned. I'm sure you will find blockage and dirt in the carb and also in the small orifices for air and fuel flow.

I took my carburetor off and blew it out with compressed air. Runs great now. Make sure to get all of it. Little screw on bottom has a hole in it too!

shaft is tapered plate just slides up on shaft, tap with hammer several times if want break loose,sometimes moisture has rusted it or excess heat has swelled it on tight, i had to take a drimel tool will cutting disk to remove mine,then clean up shaft with file or sandpaper to smooth,little grease an new collar ready for blade.