Service & Maintenance Question
I have a 350 and a 455 rancher chainsaw. Always ran great. I...
Service & Maintenance Question posted November 5, 2015 by Kyle Martin
1151 Views, 8 Comments
Question:
I have a 350 and a 455 rancher chainsaw. Always ran great. I began using xp premix fuel and after the first tank in each the saws will idle and as soon as I pull the trigger they die. I'm not sure if this was just coincidence with it happening to them both. Any suggestions?
Answer
Sounds like time for a carburetor tune-up on both saws.
Be the first to rate this
|
Kyle,
Its not uncommon if you change fuel mixtures that your chainsaw may need a little adjustment, this is true even if you mix your own but happen to add just a little less oil when making your own 50:1 mix. I agree with Eugene its time for a tune-up and carburetor tweak. If the chainsaw dies when pulling the trigger, then typically the carburetor needs to be a little richer, possibly about an 1/8 - 1/4 turn counterclockwise (CCW) on the "L" low needle should fix the problem, but you also want to make sure that everything else is correct too, like the engine is getting the right amount of air thru the air filter, and the filter is not clogged. It is also possible that some carbon may be building up in your exhaust port, this will also change how air flows thru the engine and will give you the same symptom too
. But since it is happening on both chainsaws then its most like just a symptom from the fuel change and a small tweak.
I hope this helps,
Karla
PS. I am Not a Husqvarna Representative or a Repair Service, just an experimental chainsaw person
Be the first to rate this
|
Kyle,
Also you may want to give your premix just a little shake before you dump the container into the fuel tank, I also always give my chainsaw just a little slosh or shake when I pick the chainsaw up and before I start the engine.just agitate the fuel and oil together,
Be the first to rate this
|
Did seem to help initially, but now it spins when idling and T is backed out. And after cutting through a few logs it dies and won't restart again. Any other options?
Be the first to rate this
|
Kyle,
If the clutch doesn't stop the chain from moving when you turn the "T" adjustment completely counter clockwise, then you have bad clutch springs and they will first need to be replaced, the springs cost about $2.99. After you replace the clutch springs, you will be able to turn the "T" adjustment back in or clockwise about midway, this will then let you start the chainsaw.
There is an interaction between the "T" adjustment and the "L" adjustment and that is why the chainsaw started but now that its backed out all the way, the intermediate idle which you need to start, and holds the throttle plate open just a little has been taken out of adjustment.
Anyhow, put all the adjustments back to where they were before you touched them, and replace the clutch springs, and that should fix your problem with maybe a final tweaking after you get it started, I would also Inspect the clutch and drum really good, If the clutch or drum is really worn, then this could give you a similar symptom as a spring problem. Usually however the clutch will have a bluing color to it, meaning it hot gotten really hot, and then the heat effects the spring tension. If the drum interior is really worn, or the clutch shoes are really worn, then you may have to replace them.
Let me know what you discover, and I hope this helps,
Karla
Be the first to rate this
|
T = Idle Speed L = Low Speed H = High Speed
There very little interact between T and L adjustments. It is the L and H that interacts fuel mixture wise. On some saws L need to be run on the rich side to slow the overall idle speed down. This is especially true on Stihls. The base initial carburetor adjustment is 1-1/2 turns out from lightly seated for both L and H. The T adjustment needs to be in enough initially for engine high idle from which then you back it out to slow the idle speed down. The L mixture is set for best idle speed and enriched a little for best throttle acceleration and then H is set to best top speed but not to exceed the saw's max rpm. If it should happen to exceed the max rpm then H is enrich to slow it down to the max speed.
Sometimes you can not get an engine to idle properly when the metering diaphragm hardens (becomes stiff) with age. This hardening will affect the idle mixture as it will lean out the carburetor by not allowing enough fuel to enter the metering chamber. It is same effect as if the metering lever is set too low.
As Karla said bad clutch springs will cause the clutch to engage at slower speed. These engines should be able to idle around 2900 rpms with a clutch engage speed of around 3800 rpms.
Be the first to rate this
|
Kyle and Eugene,
Here is why there is interaction between the "L" and "T", and actually If you include the "H" yes there is fuel interaction between the shared reservoir inside the carburetor that feeds both the "L" and "H"adjustments.
But the "T" adjustment interaction is actually an air adjustment or the amount the throttle plate is held open, what happens though is the more air that goes thru the venturi creates more vacuum on the Jets inside the carburetors' venturi which changes the fuel into the engine, and hence changes where you initially set the "L" adjustment. If for example the throttle plate were completely closed then theoretically (however the throttle plate is not a completely air tight seal) No air would go thru the venturi and No fuel would go into the engine regardless of where you had the "L" adjusted to, so the interaction is actually in RPM's one being controlled by fuel ("L" adjustment) and the other being controlled by air flow ( "T" adjustment). Also consider the other extreme where the throttle plate is held open too wide, then when the engine tries to start it will be drawing air across the main jets and not the idle jets for starting the engine.
I also agree with Eugene about checking and using the manufacturers settings for a starting point.
One last thought, I always adjust my "L" adjustment first to get the engine to idle, followed by the "H" adjustment second, and finally the "T" adjustment last, Then after adjusting the "T" it is always a good idea to go back and just check the "L" setting. Always start from the Manufacturers recommended settings, and even the same Manufacturer uses a wide difference of carburetor settings depending on the CC's of the engine size, and the Manufacturer and Model of the carburetor. I recently adjusted a Model 435 with a Zama C1T-EL41 carburetor, and factory settings were "L"=2 1/2 turns, and "H"=2 turns, and the "T" adjustment about 40% on the Taper screw. So there can be a very wide assortment of factory settings, make sure your using the ones recommended for your model and carburetor. Oh, and the "H" adjustment I always check both unloaded and then loaded, sometimes the "H" will need another little tweak when its under load or in a deep cut of hard wood.
Sorry to be so wordy, but just wanted to explain the interaction. Oh, I also always adjust my carburetors 1/8 turn towards the rich side which insures its getting sufficient oil and fuel, and Not adjusting it to lean, I also often verify my settings with a Tachometer but usually as a double check that everything checks out OK when I'm done.
Karla
Be the first to rate this
|
Not wordy at all to me. It explains what need to be explained. I agree that throttle plate controls air flow which controls the overall amount fuel drawn into the engine and that it being too closed can cause excessive fuel to drawn in.
The adjustment steps explained are best way to adjust a carburetor that is out adjustment after the initial starting point is set.
I have seen those carburetor settings for the 435/440e in the workshop manual here. Those stratified scavenging port carburetors always seen to be set richer for mixture screws or at that what I seen on the Poulan 4218 AVX versions. I haven't a seen a 435 or 440e in the shop just the Poulan versions
I haven't seen one of the Zama C1T carburetors yet. Mostly I see the Walbro versions of the stratified scavenging port carburetors. Thanks for the heads up on it as I need to put a RB149 kit in the stock inventory here. Most customer usually want their chainsaws fix yesterday and I have a 2 day business day shipping from my vendor on Walbro and Zama carburetor kits which means it takes a least 3 days even on a rush job unless the kits are in stock.
No telling what new versions we will see with the new Zama Philippine's plants coming online.
Be the first to rate this
|