Chainsaw stalls on throttle, idle, or under load: Causes and solutions
The two-stroke engine works by interfacing with a carburetor and ignition system to supply fuel, air and spark to the combustion chamber. If these components and the piston group of the engine malfunction, it can lead to serious problems with the tool. Unscheduled shutdown of a running engine is a frequent occurrence due to defects in key system components. Fortunately, in 90% of cases, you can find the source of the problem and restore performance on your own, with basic skills and minimum cash or time costs.
Why a chainsaw stands under load
In some cases, the chainsaw under load can not work properly and just lies down. A common cause for this behavior is improper carburetor adjustment or air intake through the crankshaft oil seals or carburetor gaskets. And it can also be due to a leaking carburetor.
To diagnose the cause and fix what the chainsaw starts and stops under load, this is best done at a service center, as a special tool is required to check the carburetor and engine crankcase leaks.
A saw that can’t run under load is also hesitant to hold up. They will float. Diagnosis begins with checking the crankcase and carburetor leaks. If air is found to be leaking through the crankshaft oil seals, they must be replaced. If air intake is detected in the carburetor, a gasket repair kit can eliminate the cause.
Hello! I have a Husqvarna 137. Recently it’s been harder to start and immediately stops as soon as I start the engine, I have to change the choke and pull starter (no primer) until it fires and then I have to throttle all the way and immediately start sawing. After you have been sawing for a while, you can release the gas pedal, then the saw won’t stall. That is, in order not to stall, the engine should warm up, and until then, you need to squeeze the gas to the full. The saw is 7 years old; the air filter is old, but I recently washed it with soap and water and it looks clean. What could be the problem?? Maybe I should clean the spark arrestor?
bondmich wrote : Hi all! I have a Husqvarna 137. Starting is more difficult to perform lately and it stops right away when I start, I have to change the choke and pull starter (no primer) until it finally starts and then I have to throttle all the way down and immediately start sawing. After you have cut the saw a little, you can release the gas pedal, then the saw will not stall. So, in order not to stop the engine, it has to warm up, and until then you need to squeeze the throttle to the full. The saw is 7 years old; the air filter is old, but I recently washed it with soap and water and it looks clean. What might be the problem? Maybe the spark arrester should be cleaned?
Check your fuel filter to see if it is dirty yellow or brown and white and check your muffler and spark plug for carbon deposits. If your carburetor is normal then you may need to adjust the carburetor.
I agree with the previous statement. Check the carburetor.
bondmich wrote: My saw is 7 years old; air filter is old, but I recently soaped it up and it looks clean.
You can wash it in pure gasoline (nothing will happen to it), but it would be better to replace it and the fuel filter. Of course you need to disassemble and wash the carburetor (especially the mesh which is inside). Write to help or not, then we will think further.
The age of the saw is not determined by years, but by how much oil the saw ate in the gasoline mixture?
Dimon 35 wrote: The age of the saw is not determined by the years, but by how much oil the saw has “consumed” in the gasoline mixture?
well the age is also important, for different rubbers 10-12 years and are starting to be old. increase idle speed with idle speed screw to stop the chain running around on the bar, change fuel filter, clean air filter, and then get in the carburettor last if the first items will not help. but if the hot saw runs fine then I think the problem is low idle, if the carburetor or filter is clogged then it is equally clogged regardless of engine temperature.
With the “age” of the saw, the carburetor sometimes wants to adjust, especially the L jets.
Kozak wrote: Then go to the carburetor in the last place if the first points do not help.
You don’t say, I myself have a similar (142), I have to climb.
Yaroslav 1 wrote : With the “age” of the saw| the carburetor wants to adjust sometimes
I agree, 137-142 carburetors like adjustments.
May I join this old thread, apparently with respect to X it is immortal. Brand new, unused 140 model saw sold incomplete without fuel filter. Apparently without any output control at all. Now it stalls in 2 seconds after starting. My saw is hopelessly damaged?
AndrewL wrote: May I join this old thread, apparently with respect to X it is immortal. Brand new, unused 140 model saw sold incomplete with no fuel filter. Looks like no output control at all. Now it shuts down after 2 seconds after starting. My saw is hopelessly damaged?
AndrewL. so it has been running for a year without a filter? Working without a filter, even for 2 or 3 days, the carburetor gets clogged! And only an experienced technician can check everything to clean it HOW MUCH AND WHERE MUCH MUCH is needed. It is not as easy as it looks, believe me
AndrewL wrote: May I join this old thread, apparently with respect to X it is immortal. A brand new, unused 140 model saw is for sale incomplete without fuel filter. Looks like no output control at all. Now it shuts off after 2 seconds after starting. My saw is hopelessly damaged?
AndrewL. so it has been running for a year without a filter? When working without filter, even for 2 or 3 days, the carburetor gets clogged! And only an experienced mechanic can check everything and clean it HOW and WHERE it needs to be cleaned. It’s not as easy as it looks, believe me
Mitriy. Saw has been used very little since purchase a year ago in winter 2016. I sawed off a few boards while renovating my house and left it until February 2017. Now after starting it, it runs hard for two seconds and then stops. I certainly found a fuel filter in the store, but to apply safety measures, as I understand, too late girl knocked up. I can clean the carburetor myself? Maybe there’s some easy-to-reach sieves to clean? And it may be so that the entire carburetor will have to change? I’m cold without firewood. There is a nearly dead Pro Arab 8545, with almost no housing and a broken starter impeller. I’m going to try to revive the Chinese. I thought it would last till the end of my short life. It’s a bargain.
Husqvarna 137 small chainsaw belongs to the category of amateur equipment. The product is light, handy and compact. It’s popular not only in households, but with professional woodcutters as well. Construction workers, rescuers and foresters are all in demand, because it is convenient for them to work in hard-to-reach places and cramped conditions.
Causes of chain saw malfunction
If the chainsaw does not start, then you need to conduct a step-by-step diagnosis. It is recommended to go from simple to complex and to do everything in order. Although devices from different manufacturers differ from each other, the principle of operation and layout they have the same: at the heart of a two-stroke gasoline engine, which through a reducer rotates a tensioned cutting chain.
The diagnostics must be performed in sequence:
- Inspection of filters.
- Checking the electrical system (whether or not there’s spark on the spark plug electrodes).
- An inspection of the fuel supply and the breather, which is built into the fuel tank cap.
- Examination of the exhaust ducts.
Each of the four steps should be examined separately.
What you’ll need for repairs:
- A set of car wrenches, screwdriver, and sockets.
- Screwdrivers: Phillips and slotted screwdrivers, flat spatulas for cleaning parts.
- Metal brush (cordbrush) and brushes with a stiff lint.
- A basin for washing parts (a cut off plastic canister will do).
A compressor is recommended for blowing out motor parts. Never use industrial gases (especially oxygen).
Dirty filter on the chainsaw If the chainsaw has been running for a long time, the air or fuel filter may not be clogged. In the first case, the right portion of air will not get into the cylinders, combustion of the fuel mixture will not occur. If the fuel system is clogged, the petrol mixture will stop flowing.
Air-cleaning element should be removed carefully, dust should not enter the carburetor. It should be blown and washed with soap and water, dried and reinstalled.
To check the condition of the fuel filter you need to remove the hose from the carburetor, try to pump fuel manually. If the trickle is too weak or completely absent, the filter must be replaced or flushed. You can buy a new one from your dealer or have your power tool repaired by a repair shop.
Check the spark plug
Perhaps it is necessary to put new plugs The operation is similar to the one that all motorists with gasoline engines. If you have a new and 100% working plug, it is easier to put it in stock and try to start the chainsaw. The old one should be inspected: heavy soot indicates that the engine is not running properly. If there are no deposits, the electrode gap might be broken and that’s why the spark stops working or is too dim. The distance between the contacts varies from 0.2 to 0.5 mm.
- Remove the high voltage wire.
- Unscrew the spark plug and reattach the previously removed wire.
- Lean the “skirt” of the spark plug against the unpainted part of the cylinder.
- Try to start the engine.
You can try to disassemble the ignition unit, clean the contacts, dry, assemble and try again. A number of faults cannot be eliminated, so in some cases the unit will require replacement, but this is an extreme measure.
Gasoline supply. The breather
The breather plug is one of the hardest parts of the test.
The first step is to prepare the work area:
- Remove the dirt and dust from the workbench.
- Prepare a clean rag, brushes, containers for washing small parts.
- If you have a compressor, have it ready to blow out the carburetor holes.
The chainsaw itself needs to be cleaned and blown with compressed air. Now you can proceed to the diagnostics.
- Fuel tank. no dirt, iron filings, sand and other impurities inside.
- The breather, built into the lid. through it air must enter the tank, otherwise during operation a vacuum will be created and the fuel will not enter the carburetor.
- Hoses and pipes. for cracks and other defects. Replace if there are any suspicions.
After assembly it is necessary to check: if after the manual priming with the carburettor removed the feeding tube the petrol mixture flows in a tight stream with jerks then the system is in order. If the chainsaw still won’t start, it’s the carburetor’s fault.
The exhaust passages on the chainsaw may need to be cleaned After prolonged use, the chainsaw’s exhaust passages may have hardened, causing resistance to the forward movement of the piston. Simply put, unremoved gases slow down the engine.
- Remove chainsaw muffler.
- Carefully remove the gasket.
- Dismantle the spark arrestor.
- Disassemble the resonator housing (if possible).
- Clean parts with detergent solutions (kerosene, WD-40) and mechanically.
- Clean, dry assemblies.
- Reassemble the system.
Chainsaw stalls when pressing on gas. How to adjust the carburetor
Switching system device
The carbureted two-stroke power unit plays a key role in any chainsaw. Its capacity depends directly on the chosen model and purpose. The second important mechanical component in the appliance is the saw unit, which consists of the bar, cutting chain, and chainwheel. Parameters of these components can vary.
The machine is lubricated with a special oil reservoir on the handheld unit. It should be emphasized that the volumes of the oil tank and fuel tank are calculated in such a way that their content is usually finished at the same time.
Troubleshooting options and remedies
Regardless of the brand of chainsaw. Champion, Husqvarna 236 or Patriot, the causes of poor performance are identical. There are lots of ways to find out why a STIHL chain saw does not start, but the most common are.
The chainsaw does not start well in the cold
If a chain saw fails to run cold, it usually has no compression. This is due to ring wear and tear from continuous use. It turns out that when the user tries to start Champion 137 when it is cold, there will not be enough compression to perform this manipulation.
In such a case, it is not recommended to systematically pull the handle. The machine will eventually start but other mechanical components may be damaged. In this situation, replace the worn rings with new ones.
This chainsaw does not turn on hot
Here the causes are the engine priming and the spark plugs are wet. Here’s what to do in this situation:
- Move the choke to the middle position;
- Blow out the component parts well;
- Start the machine for 10 seconds;
- switch to idling mode;
- On a Kalibr or other model chain saw open the choke completely.
Next, simply start the engine at idle speed by pulling the handle. If the engine is not overheated, it will start easily.
If this troubleshooting option did not help, it means that the engine has already cooled down a lot. Do the half throttle lock as recommended in the manual and repeat the operation.
You should also try to turn the cold running screw in the clockwise direction. The higher the speed of rotation in the equipment, the easier it is to start. Be aware that the circuit, when idling, must remain in the stationary position.
The chain saw does not start well and immediately stops
In this situation, the reason is the flooding of the spark plugs with gasoline at the moment when the user tried to start the machine. A small amount of fuel accumulates under the spark plug electrodes, causing no spark in the equipment.
The problem can be solved by removing the plug and drying it thoroughly. In addition to these actions, you can carry out additional heating. But this manipulation should be carried out exclusively with a gas torch. In another case, a small amount of soot may form in the area of the electrodes. After the spark plugs are completely dry, you need to drain the excess fuel and leave the equipment to dry.
The chinese chainsaw will not start
It should be noted at once that Chinese devices do not have any distinctive features from other analogs. They are just as reliable and productive, moreover, they cost less. The only thing that is necessary individually for this device is to use only branded oil and fuel.
Most units do not work well on domestic fuel, gasoline clogs the channels and as a result, the fuel does not come to the engine. Use only high-quality fuel or fuel from the manufacturer of the saw.
Why does the new saw not work
New equipment should have no problems with the wear and tear of functioning mechanical parts, since the model has only just come off the assembly line. Such untidiness may occur in the case of purchase of demonstration equipment, which is not once used to promote the company. Also improper use of the machine in a manner inconsistent with the recommendations in the instruction manual could be the cause.
First check that all parts and components are in place. Also, for example, Husqvarna will not start if it has been filled with a fuel mixture prepared without taking into account the correct proportions.
But if all the recommendations are followed, each part is carefully fixed in its place and the equipment was not purchased from the stand, probably the buyer got a defective device.
How to change the sprocket?
If you need to replace the sprocket on your Husqvarna 137 chain saw, the following algorithm must be followed:
- Open the side cover that gives access to the bar and sprocket.
- After loosening the chain, you must remove the bar.
- When the sprocket is loose, unscrew the spark plug to gain access to the motor piston.
- You have to turn the sprocket by hand.
- The piston is brought almost to the highest point of the channel.
- The resulting hole should be filled as tightly as possible, using a soft candle cord. That way you block the movement of the piston.
- To unscrew the sprocket, use a wrench.