Stumped

[Jsarment]

Hi folks. I'm working on a Ryobi backpack blower (small). Starts ok but will only run at half choke. As soon as you open the choke all the way it dies out. It seemed like a clogged muffler so I took it off and same thing. I took the carb off and cleaned it out even though it looked fine. Any ideas? Help? Thank you in advance.
Jeffrey

 

[mechanic mark]

Replace fuel filter in tank, air filter, spark plug, fresh gas & 2 cycle oil, use OEM Ryobi parts & gap plug to specs.

 

[Lawnranger]

If doing what Mechanic Mark said doesn't work then try the following. You said you took off the muffler and it did the same thing, but what about the actual exhaust port in the head? Sometimes carbon builds up so much in the port it restricts the same way as a plugged spark arrest screen. While you are in there, take a flashlight and a small plastic or non-metal tool to push in the piston ring to see if it moves a little bit. The ring should be free to move a small amount and if it does not then take a closer look at the cylinder for scoring. This is very easy to do while you have the muffler off and the spark plug out using a flashlight to aid inspection.

Another factor is the age of the machine. If the blower is over four years old I would suspect the metering diaphragm and inspect for stiffness/wrinkles/popping or clicking noise when flexed and replace in the event of the aforementioned. If any doubt put a kit in the carburetor. If the machine is relatively new then maybe all that is needed is a carburetor adjustment due to being set incorrectly from the beginning.

You mentioned that it runs at half choke but with choke off it dies. This leads me to think it's fuel related and running lean. The probable cause of a lean condition is the metering diaphragm because carburetors don't just go out of adjustment all by themselves and if you adjust, you'll probably chase the adjustment. Another possible cause is an air leak in the crankcase or between the carburetor & intake - not very common but it does happen.

 

[Carscw]

I find it best just to replace these tiny carbs. Rather then mess with cleaning them.

 

[redmondjp]

I find it best just to replace these tiny carbs. Rather then mess with cleaning them.

After wasting far too many hours of my life on these, I couldn't agree more. I have found that one can obtain brand new replacement carbs on Amazon for $35-50 for most of these small 2-cycle engines. The carb make and model number can usually be found right on the side of the carb (sometimes laser-engraved, sometimes very faint black lettering) if you look for it hard enough. Then Google is your friend.

Bolt the new carb on, add some fresh fuel, start it up, and then adjust idle speed and high and low speed mixture screws (if so equipped).

But if there is a high-speed fuel adjustment (which in some cases is hidden underneath a plug), I'd try adjusting that first.

 

[Carscw]

After wasting far too many hours of my life on these, I couldn't agree more. I have found that one can obtain brand new replacement carbs on Amazon for $35-50 for most of these small 2-cycle engines. The carb make and model number can usually be found right on the side of the carb (sometimes laser-engraved, sometimes very faint black lettering) if you look for it hard enough. Then Google is your friend. Bolt the new carb on, add some fresh fuel, start it up, and then adjust idle speed and high and low speed mixture screws (if so equipped). But if there is a high-speed fuel adjustment (which in some cases is hidden underneath a plug), I'd try adjusting that first.

I get mine off eBay.
Most things on Amazon I can get for the same price at the dealer.

 

[hot pipe]

have to say when cleaning any carb best to pull the fuel mixture screws.L/H side a must.... I come across way to many carbs that have been cleaned and rebuilt brought to me for repairs and i simply count the turns in to seat the needles write the settings down pull the needles out disassemble the carb flush out through the needle threaded holes and back thru the ports...reassemble the carbs reset the needles and good to go..not saying every carb is that easy though
but most are... but you also need all the right tools to do so... or a dremel tool if need be.