Need a little advice on my Briggs and Stratton

Hello, My name is Red and I have a Bolens Lawn Tractor with a 2008 Briggs and Stratton I/C 500cc 15.5hp Model #31A6070741B2 which had been sitting for a few years. Started working on it a few days ago to getting running again. After changing oil, spark plug, air filter, and draining old gas and adding new non-E fuel and changed fuel filter. I took apart the carb, cleaned and checked to make sure everything was working properly which it all seemed so. Re-installed, mower starts up first try, runs great for about a minute then it starts idling up and down and does this for several minutes then shuts off. From here it will not start unless I put my hand over the intake hole, the choke doesn't do the trick at this point. It will start but after about 10 seconds it starts it's idling thing again and wants to shut off, but I can keep it running if i cover most of the intake hole. I was thinking I need to get a rebuild kit for the carb but wanted a little insight first. Any advice would be great. Thanks

 

short answer Yes you need to rebuild the carb for sure with new gaskets etc.
I would also put some seafoam in the gas tank to remove any moisture that may have accumulated.

 

I believe I would use the Sea Foam first - about 2 ounces in a quart of gas. Let that be the only mix in the tank. Then start it and let it run until it dies. Let it sit for ten minutes and start it up again - see if it's any better. If it doesn't improve after a couple of times through with the Sea Foam, then rebuild the carb.

 

Since it starts and runs fine for a minute before the problems start, I'd say your carb is fine. You have a fuel delivery problem to the carb and your bowl is running dry. Check flow from the tank to the carb, and if that is fine, drop the bowl and see how much is trickling out the float valve. I bet you'll find that it's just a very tiny trickle.