I have a Stihl 009 chain saw that I just rebuit the carb on and when it runs at high speed it does so only for a few seconds then dies. It will idle all day long. What could the problem be?

carby idle adjustment or a carby kit and clean needed

carby has a high and a low rpm jets

STIHL MS 290, 310, 390

https://www.stihlusa.com/.../instructionmanuals/stihl-ms-290-310-390-owners-instructio...
Instruction Manual - improper use can cause serious or fatal injury. MS 290. Warning! ..... model. Safe use of a chainsaw involves. 1. the operator. 2. the saw.

Most Chain Saw Engines Have Three Carburetor Adjusting Screws:
1. Idle Speed/Throttle Stop - This is the adjustment that controls how much the throttle valve (butterfly) stays open when the throttle trigger is released. If this adjustment is set too low, the engine will die when the throttle trigger is released. The throttle valve (butterfly) simply cuts off the supply of combustible air/fuel and the engine stops. If this adjustment is set too high, the high idle speed will cause the centrifugal clutch to engage and the chain will run. This is a dangerous condition and should never be allowed.
2. Low Speed Fuel Adjustment (marked L on carb, this is the low speed jet)- This is the adjustment that controls the proportion of fuel in the combustible air/fuel mixture at idle speed. An adjustment that is set too rich will cause the engine to load up and die at idle speed. A mixture that is too lean will starve the engine and cause it to race or surge. An extremely lean adjustment will cause the engine to die, too.
3. High Speed Fuel Adjustment (marked H on carb, this is the high speed jet) - This is the adjustment that controls the proportion of fuel in the combustible air/fuel mixture at cutting speed. It would not be accurate to say that this is the most important setting, because all of these adjustments need to be accurate for a saw to perform its best, but this is the adjustment that determines how the saw runs in the cut. An adjustment that is set too rich will not allow the saw to reach the RPM level necessary to build maximum power. Throttle response may also be sluggish and the engine would smoke and perform poorly. A mixture that is too lean will allow the engine to reach an RPM level where bearing failure and cylinder seizure are likely. It will also lack power in the cut and tend to run very hot.
The preceding information briefly explains rich and lean running conditions. It also identifies the three adjustment screws and their function. It should be noted that some chain saws lack the high speed adjustment needle. These saws have what is called a "fixed jet" which is set from the factory. "Fixed jet" carburetors are used to prohibit the saw operator from setting the adjustment too lean and damaging the saw. Unfortunately, they also often prohibit the saw from achieving maximum performance.

I have found that replacing the carb. with a new one . Usually between 27.00 to 38.00 dollars usually saves a lot of time over installing a kit. problem is usually due to a jet problem or the ethanol in the gas has removed the coating on a plug inside the carb. which requires carb. replacement

You need to adjust your idle screws. Start at 1 and a half turns out for High and Low then go from there.

have u tryed adjusting idle screw

The paper pumps get stiff and do not pump fuel very well. It's the new Ethanol gas that is the Carb Killers. You need a rebuild kit not just disassemble and clean.
You have IDLE ADJUST Low Speed adjust and High speed adjust. Low and High speed adjust have nothing to do with Idle.

You have an internal circuit leak in the body itself, my friend. Get a new carb, it's still going on a $1000 saw and will make it run like new again.

I'd guess at a dirty carb. If its been sitting the gas may have gone bad and clogged up the carb. Try spraying some carb cleaner in the mouth of the carb. It's possible that the idle is turned up too high to compensate for clogged ports in the carb. This is a possibility but not a guaranteed solution. Good luck.

Sounds like a carburetor issue. Chain saws get the &**^% beat out of them during normal use.

This may just be a fuel jet adjustment if the carburetor has one. Sometimes there is a low speed jet and a separate high speed carburetor jet. Check for both. Also, check to see if the carburetor is loose - like I said, chain saws usually see some pretty rough service and things can loosen up.

If no joy on the above, you may need to clean the fuel tank, the fuels line, and the carburetor. This requires taking the carb apart so if you aren't familiar with this kind of work, take it to a shop.

Also, make sure the fuel mixture being put in the saw is correct

hi leobowdy

disassembly the carb and carefully clean it.Check the air filter,the fuel line and fuel filter,check the needle,lever,small spring and the screen filter from the carb.Check the sparkplug.
high speed H=2 turns,low speed L=2 1/2 turns,adjust T
When chain saw starts adjust H,L and T accordingly.

cheers savumihai71.