Husqvarna 359: Has run fine for 3 years. Now when first starting idles fine but as soon as it warms up idle speed increases enough to continually engage the clutch. Carb. setting have never been changed until now. Tried to adjust idle speed (T) down. This helped while adjusting but as soon as I start using again idle speed increases. New air filter, gas, fuel filter and plug. Any Ideas? Thank you in advance!

https://data2.manualslib.com/pdf/8/741/74034-husqvarna/340.pdf?658888cc1e965ad6a8e290b6dfb24620&take=binary Review adjustment procedure starting at page 37.


It's a bit of an art and you have to be able to hear the slight changes in combustion and engine speeds. It took me years to become what I consider "proficient" and not struggle with adjustments of a 2 cycle. You must adjust the idle air/fuel mix first, then high speed. I read improper instructions regarding this all the time. The low speed circuit has to be set first because it changes the overall mix when high speed is open. Any changes in low speed air/fuel mix affect high speed (not the other way).


Start by remove chain. Begin with both H and L screws at 1 to 1 1/4 turns out. You want the idle speed high enough that it runs well enough to get through the idle mix adjustment without dying, but not so high that the carb high speed is opened. So if its dying while adjusting low speed, increase the idle speed. If you can't get idle adjusted without it dying, then likely you have other issues with the carburetor, spark, compression (crankcase seal) or even blocked spark arrestor screen.


Once you have low speed adjusted, you begin on high speed adjustments. See instructions. If the saw does not want to accelerate without stalling and you have opened the high speed screw, then likely the high speed circuit is fouled or there's a crankcase leak.

you problaby have a missfire, you need to check it out soon or it will have some damage on your catalyctic converter

on a cold start car will idle fast till it warms up then will drop to about 1000 rpm, try increacing idle speed so when it warms and drops it should stay idleing

Turn both H and L jet needles CW to stops (lightly), then back out 1-1/2 turns each CCW. This is a basic setting and will be rich. Start the engine and allow to warm up. Pull the throttle full on and turn the H needle CW until the engine starts to speed up, but continues to 4-stroke. Final adjustment is when the engine 4-strokes at speed with no load, but immediately 2-strokes when cutting. Release the throttle and allow to idle. Turn the L jet needle CW until the engine idles fairly well, but still allows the engine to 'follow the throttle'. Idle speed screw should be adjusted to keep the engine idling, but the chain should not try to turn. Hope this helps!

Turn both jet needles CW to stops (lightly), then turn each screw out CCW 1-1/2 turns. This is a basic setting which should allow the engine to start and run. Start the engine and allow to warm up, then pull the throttle full on. Adjust H needle CW until the engine starts to speed up, but still 4-stroking. Proper final adjustment is when the engine 4-strokes unloaded, but immediately 2-strokes when cutting. Release the throttle and adjust L needle CW for better idle, but still allows the engine to 'follow the throttle'. Set the idle speed screw so that the chain stops turning, but the engine will continue to idle. Hope this helps!

I think you are saying it sputters but won't run. Once it attempts to fire open the choke or it may flood. My 359 start:
Cold: pull out choke control, pull starter (usually twice) while listening for attempt to start. Once it fires push choke control in and
continue pulling (usually once more).
Warm: pull out choke control (sets fast idle), push choke control in, pull starter.
Page 19 of my manual.
Lou
Once flooded these are a bear to start.

My name is Dennis and I also have the model you are having difficulty with and I can only repeat the instructions from the owners manual (with personal comments) because they have always served me adequately I hope that will serve your needs.
IDLE ADJUSTMENTS:
There are three adjustment screws on the carburetor labeled
H (for High speed MIXTURE)
L (for low speed MIXTURE)
T (for idle SPEED SETTING)
They are located just above the primer bulb. If your saw floods so soon in the starting process the idle mixture setting can be set too rich and the speed may be set too slow. Remember the chain will not move when the idle speed is set correctly with a WARM ENGINE!
Adjust the idle speed to just below chain movement WITH A WARM ENGINE this is just below the activation RPM of the centrifugal clutch. Let the engine run at a higher speed than idle until it is warm -- 3 min -- you may have to keep goosing it until then.
Please don't exceed the limits of the plastic limiters when making adjustments.
If you haven't adjusted the mixture screws you may just have to adjust the idle speed and that can start my turning that screw all the way in to the stop and then back out 4-1/2 turns for a good place to start. FAST IDLE -- Adjust the speed until the engine runs with out the chain moving. Adjust clockwise to increase speed. C clockwise to decrease engine speed.
Accelerate the engine and if it stumbles and makes too much smoke it's too rich turn the
LOW SPEED MIXTURE (in) clockwise in 1/16 a turn increments NO MORE at a time because a two cycle needs to run at a setting for a short time to really prove the setting. don’t run it wide open to warm it up but it should be at a fast idle. Nothing you do will be proven correct until the engine is warm.
Good Luck
Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you

Hi Guest,
My name is Dennis and I also have the model you are having difficulty with and I can only repeat the instructions from the owners manual (with personal comments) because they have always served me adequately I hope that will serve your needs.
IDLE ADJUSTMENTS:
There are three adjustment screws on the carburetor labeled
H (for High speed MIXTURE)
L (for low speed MIXTURE)
T (for idle SPEED SETTING)
They are located just above the primer bulb. If your saw floods so soon in the starting process the idle mixture setting can be set too rich and the speed may be set too slow. Remember the chain will not move when the idle speed is set correctly with a WARM ENGINE!
Adjust the idle speed to just below chain movement WITH A WARM ENGINE this is just below the activation RPM of the centrifugal clutch. Let the engine run at a higher speed than idle until it is warm -- 3 min -- you may have to keep goosing it until then.
Please don't exceed the limits of the plastic limiters when making adjustments.
If you haven't adjusted the mixture screws you may just have to adjust the idle speed and that can start my turning that screw all the way in to the stop and then back out 4-1/2 turns for a good place to start. FAST IDLE -- Adjust the speed until the engine runs with out the chain moveing. Adjust clockwise to increase speed. Cclockwise to decrease engine speed.
Accelerate the engine and if it stumbles and makes too much smoke it's too rich turn the LOW SPEED MIXTURE (in) clockwist in 1/16 a turn incriments NO MORE at a time because a twocycle needs to run at a setting foe a short time to realy prove the setting. dont run it wide open to warm it up but it should be at a fast idle. Nothing you do will be proven correct untill the engine is warm.
Good Luck
Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you
Your IDLE MIXTURE may be too rich causing the engine to flood.

Hi 1tgriffin,
My name is Dennis and I hope that will serve your needs.
IDLE ADJUSTMENTS:
There are three adjustment screws on the carburetor labeled
H (for High speed MIXTURE)
L (for low speed MIXTURE)
T (for idle SPEED SETTING)
They are located just above the primer bulb. If your saw floods so soon in the starting process the idle mixture setting can be set too rich and the speed may be set too slow. Remember the chain will not move when the idle speed is set correctly with a WARM ENGINE!
Adjust the idle speed to just below chain movement WITH A WARM ENGINE this is just below the activation RPM of the centrifugal clutch. Let the engine run at a higher speed than idle until it is warm -- 3 min -- you may have to keep goosing it until then.
Please don't exceed the limits of the plastic limiters when making adjustments.
If you haven't adjusted the mixture screws you may just have to adjust the idle speed and that can start my turning that screw all the way in to the stop and then back out 4-1/2 turns for a good place to start. FAST IDLE -- Adjust the speed until the engine runs with out the chain moving. Adjust clockwise to increase speed. C clockwise to decrease engine speed.
Accelerate the engine and if it stumbles and makes too much smoke it's too rich turn the
LOW SPEED MIXTURE (in) clockwise in 1/16 a turn increments NO MORE at a time because a two cycle needs to run at a setting for a short time to really prove the setting. don’t run it wide open to warm it up but it should be at a fast idle. Nothing you do will be proven correct until the engine is warm.
Good Luck
Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you

The carb needs to be adjusted. Look for 2 adjustments label High(H) and Low(L). Low is the one that you want. Start you chainsaw and let it warm up and turn the L adjustment a until you are able to let it idle on its own. Hope this helps.