weed trimmer starts then quits

I have a Honda weed trimmer/brushcutter model UMK422 that will start right up on the first pull but then quits running after 15-20 seconds, then won't start again until it has sat a good while like half an hour or so. Then will start right up again but will again always quit running after 15-20 seconds. Has good fresh gas and a the gas filter is fine, and the gas lines are clear and in fine condition. Assuming a carb problem I have at least disassembled and inspected (it's a Walbro carb) and the valve needle was fine and the pump diaphragm isn't obviously bad looking (no rips and not stiff anyway). The gasket(s) look fine too. Does the symptom I describe sound like it could be remedied by a carb rebuild maybe, or new carb? What's got me rather baffled is how it'll start up fine and run, but then just quit every time as I described. Thanks for any comments.

 

99% of the time it's a fuel problem.
Replacing those tiny carburetor's is the way to go.
Using nonethanol fuel, never mixing more then 1, gal. at a time will go a long way to keep this from happening again.
Any place that sells power equipment has premixed nonethanol fuel if you can not find it locally.

 

Okay thanks joecaption1, I'll look into replacing the carb. I did see one on ebay for about 22 bucks, so if that'll take care of it the problem it at least it won't break me too bad . This happens to be a four-stroke engine on this trimmer and doesn't use mixed (with oil) gas. I've been using just unleaded from the gas station, the manual specifies unleaded fuel at least 86 octane doesnt mention nonethanol. In my area nobody sells nonethanol gas that I know of.