For others to help; are you saying it will idle but stumble and die if given gas? I personally often run into this and almost always find that cleaning the main jet area (visually dirty or not) solves the problem.

hi, i agree with chas. sounds like a fuel issue. ran good after installing new carb? how long ago.

The unit will start and run on open choke but not idle when warm, and if I gun it, will also sometimes stall. This is the behavior which caused me to buy and install (yesterday) the new carb. I test ran it without the fuel cap and it ran stronger, so I punched a hole through the center of the cap just as a means for further testing.

It is exhibiting the same behavior now as it did prior to installing the new carb.

When I press the throttle button to disengage the choke, it will idle for a few seconds and die. If I try to rev it instead of letting it idle, it luffs and usually dies. If it doesn't die when being revved, as soon as I stop revving it, it dies.

is the gas tank clean? fuel lines in good shape? your new carb could have sucked something up. if you hadn't already purchased a new carb, i would have suggested you rebuild/replace your carb. if your familiar with your carb, take it apart and give it quick spray.

brand new filter and fuel lines. i will try spraying the carb, but it has no time on it, so can't imagine that's the problem. thanks for the suggestion.

Ryobi has a very bad record for their carbs . Is your New carb sealed . If so some can be repaired by removing the jet limiter and enriching the low speed jet , which is the cause of your bogging issues . These units are set much too lean from the factory rendering them useless at some elevations .

I had already removed the muffler and cleaned the spark arrestor, but I did it again, this time with a lot of carb cleaner. Now it will idle, but sometimes quits when I press the throttle fully. getting closer. I had read that I should use a propane torch to clean the arrestor? anyone done that with success? can't replace it. the part is no longer available.

sse, i am handy but not a carb expert, so i have no idea how to do what you suggested.

lots of videos on you tube showing how to remove different types of limiter caps. just find the 1 that resembles your carb.

Sofa , rather simple , just goggle some internet sites for grass trimmer carb tuning . If this appears beyond your comfort factor , replacement carbs with adjustable jets are available at very little $$ normally under $20.00 .

Sofa , in the interim purchase some concentrated fuel cleaner and add 2 ounces to your fuel tank and run the trimmer for at least 20 minutes varing the rpm . This may clean any minute fuel restrictions within the carb . I will research your stock carb and get back to you with further advice or a replacement adjustable carb !

Yep as I thought zama adjustable carbs for your ryobi You can purchase a Pac man carb tool for your carb . The left nearest the choke housing is the low speed jet . It needs to be turned out counter clockwise a quarter turn . You can also slit the head of the jets with a hack saw blade for use with a slotted screwdriver . The zama carb comes with the tuning tool and a new spark plug , fuel line and filter and carb gaskets for $11.99 .

Thanks, everyone, for your responses!