How to tell is I have a bad Carburetor?

[fishEH]

Hi all, first post hear.
I inherited a Craftsman 5.5hp 26wide front tine tiller from my grandfather. He let gas sit with gas in it over the winter.
I took the carb apart and sprayed everything with carb cleaner. Reassemble and it fires right up and I think Sweet, I just got a $3 tiller.
I try it about 3-4 weeks later and it won't fire. Disassemble and clean again and it runs. I winterize it by siphoning as much gas as possible, and run the engine till it dies from fuel starvation. I do the same thing with my snowblower and lawnmower with no issues.
Last year I pull it out and same deal, it won't start. I buy the Carb overhaul kit and rebuild it using all new gaskets, etc. Works great for me. Works great the next day. Try it again in 1-2 weeks and no luck. I throw up my hands and let it sit all winter with gas in it.

Sooooo, do carburetors just go bad? I'd hate to drop ~$70 on a carb if it could be something else. Could it be something else?
Sorry for being long winded. Thanks in advance!!

 

[reynoldston]

you need spark, fuel, compression, and timing if any one of these are missing it wouldn't run. Just the gas setting for a few weeks isn't going to make your carburetor go bad unless you are putting real old gas into it?

 

[fishEH]

you need spark, fuel, compression, and timing if any one of these are missing it wouldn't run. Just the gas setting for a few weeks isn't going to make your carburetor go bad unless you are putting real old gas into it?

Thanks for the reply.
I get what you're saying. Spark is good. Not sure how I would check for compression or timing.
I guess I just assumed bad carburetor because the ONLY time it wants to run is after a fresh rebuild of the carb. And when it does run it runs great. It will run as long as I want if I keep the tank topped off.

 

[ILENGINE]

sometimes when the carb dries out the fuel pump diaphragm will stick and not pump fuel. Could also be the fuel that sits in the little fuel well at the top of the tank goes stale and won't start or run on, but after you get fresh fuel into the well it will run on the fresher fuel.

Next time it won't start try dumpng a small amount of fuel into the carb intake and see if it will continue to run after starting.

 

[fishEH]

Thank you. I guess part of my post was trying to see if maybe this is a common problem for Craftsman Tillers or other B&S engines?