Top Reasons Chainsaw Starts, Then Stalls — Chainsaw Troubleshooting
Three screws will help us to adjust the carburetor:
- “L”. low, for setting low rpm
- “H”. high, for setting the upper speed
- “T” (“LA”, “S”). for adjusting idle speed (models that have only one screw have exactly the “T” screw)
When adjusting the carburetor of a chainsaw, the following rules should be observed:
Poulan chainsaw won’t idle
- Make sure the saw chain is facing away from you.
- Place the saw on a stable, level surface with the cutting part not touching any objects.
Please note: the instructions indicate the exact angles of rotation of the adjusting screws. Strict adherence to the instructions in the instructions will avoid damage to the engine.
The process of adjusting the carburetor itself includes two points: basic (when the engine is not running) and final (when the engine is running warm).
We adjust the maximum number of revolutions
As mentioned earlier, the maximum RPM is set with screw H, the RPM increases when it is turned clockwise, decreases when it is turned counterclockwise.
The highest speed of rotation of engines of gasoline chainsaws is in the range of 11,500. 15,000 rpm, depending on the model. Higher speeds are dangerous for the engine and will prevent it from starting. Maximum rpm can be determined by misfiring. If any, turn the screw H counterclockwise.
Smoothly press the accelerator and see how quickly the engine picks up speed from idle to maximum power. If the engine picks up speed slowly, therefore it is necessary to loosen the L (low speed) screw by turning it slightly counterclockwise (no more than 1/8 of a turn).
Checking and adjusting the carburetor
In service centers, the carburetor is adjusted using special equipment. For each saw, the values of the angles of rotation of the adjusting screws are different (they are indicated in the operating instructions). The need to adjust the carburetor does not arise very often, especially if the saw was bought from a trusted seller. All of our Husqvarna saws are sent to the service center before being sold, where specialists adjust the speed control.
However, a misalignment of the adjusting screws sometimes occurs.
Stalls under load
If the chainsaw starts to stall under load, then the reason for this is, first of all, an incorrect carburetor setting. If this reason is eliminated, then in addition to problems with the carburetor, the reason for the inoperability of the tool under load may be damage and wear of the crankshaft oil seals or carburetor gaskets, through which air is sucked into the system.
It’s important to know! It is better to diagnose such a malfunction in a service center, where the exact cause will be established.
It is recommended to start troubleshooting by checking the oil seals and gaskets, and only after that check the correctness of the carburetor setting. Another reason why the chainsaw starts up and immediately stalls under load may be the chafing of special hoses, through which the impulse is transmitted from the crankcase to the fuel pump. But such hoses are not installed on all models of chainsaws, but only mainly on professional ones. It is recommended that this hose be replaced to rectify the problem. How to do it correctly is discussed in the video:
Final carburetor setting
First, warm up the engine for 5-10 minutes (not at high speeds).
Calibration algorithm and safety precautions when troubleshooting a chainsaw carburetor
Carburetor adjustment is carried out in two stages:
- Basic (carried out with the engine off).
- Finishing (carried out with a running, pre-warmed engine).
For basic adjustment, screw in screws H and L as far as the stop and back out 1.5 turns. Final adjustment requires the engine to warm up for 5-10 minutes at low revs.
The final calibration is performed by unscrewing the idle screw until the minimum engine speed is reached (its operation must be stable, and the chain must be stationary). If the engine stops at idle speed, the screw must be returned back, and if the saw chain is still in motion, continue turning counterclockwise.
Calibration check is performed by test:
- Acceleration (with a smooth press on the accelerator, the engine should quickly pick up speed to the maximum indicator).
- Maximum speed (if there is an ignition interruption, screw H should be slightly loosened).
- Idle work (the chain should not move, and the engine should pick up speed as quickly as possible).
If the owner of the chainsaw is not familiar with the carburetor device and does not have the tool necessary to calibrate it, contact a specialist. The carburetor is a very complex unit, so any wrong action can lead to irreversible consequences, for example, complete engine failure.
Chainsaw design and general classification of faults
Correct diagnosis is essential for a successful repair. Therefore, in order to determine why the chainsaw failed and, most importantly, how to make it work again, you first need to know the features of its design.
It should be noted that it does not differ in particular complexity, since it includes:
- engine (two-stroke gasoline);
- functional part (saw bar and chain);
- systems that ensure the joint operation of these two units (ignition, filtration, lubrication, etc.), that is, the tool as a whole.
In order to simplify the diagnosis of malfunctions, it is customary to distinguish them into two main categories:
- engine malfunctions;
- malfunctions of other chainsaw units.
The most common malfunctions occur in the engine systems, however, the rest of the tool, due to intensive use or improper care, can fail at any time. How to determine exactly where the breakdown occurred? Simple logic will help us with this.
If the problem is in the engine, it will:
- do not start;
- work unstable;
- develop insufficient power.
As for all other malfunctions, as a rule, they manifest themselves with a normally operating motor.
The device must be removed from the fuel tank (after all the fuel has been drained from it). On most models, the fuel filter can be hooked out of the wire through the neck. If the filter design is collapsible and can be cleaned, it must be disassembled and washed in accordance with the manufacturer’s recommendations. Otherwise, change to a new filter.
Similar problems can arise when the air filter is clogged with dust, sawdust, or dirt. If the amount of air is insufficient, the fuel mixture will be enriched, the fuel combustion process is hampered.
To check, remove the filter. When working, you need to take precautions so that dust does not get into the carburetor. The device must be cleaned and rinsed in warm water with the addition of detergent. After drying, if possible, blow out with compressed air of low pressure, reinstall. If the chainsaw works fine, then the reason has been eliminated, if not, you need to look further.
With continuous operation of the tool, it is recommended to replace the filters of the fuel and air systems after 3 months.
To adjust the operating modes, there are three screws on the device case, designed to set the minimum rotation speed, maximum speed and idle speed.
On many models, manufacturers install only the idle adjustment screw to avoid incompetent attempts to adjust the device. In all variants of the device, the adjustment must be carried out exactly according to the recommendations of the manufacturers.
If the adjustment of the device did not lead to the restoration of the normal operation of the tool, it is necessary to completely disassemble the device with an inspection. It should be understood that a carburetor is a rather complex device, in the absence of experience, it is advisable to contact a specialist.
When disassembling, it is important to carefully inspect and flush all jets, air and fuel channels, and filter mesh. Damaged elements must be replaced with new ones. The jets should be cleaned with a soft wire of the appropriate diameter.
It is advisable to carry out the work in appropriate conditions. The carburetor contains many small parts, the loss of any of them will make the device inoperative.
Checking the carburetor and signs of need for adjustment
A properly working carburetor guarantees maximum efficiency of the chainsaw, that is, it is possible to develop full power with the most economical consumption of the fuel mixture. The adjustment of this unit is usually carried out by the manufacturer, but its design provides for the possibility of adjustment already during operation.
The fact that such a setting will have to be performed by the owner of the chainsaw is evidenced by:
- Strong vibrations or damage to the protective cap.
- CPG wear.
- Carburetor clogged.
- Inability to start the engine or its spontaneous stops after starting.
- Increased fuel consumption and exhaust emissions while decreasing engine power.
Chainsaw carburetor adjustment is carried out in strict accordance with the manufacturer’s instructions using three special screws that are responsible for the maximum (“M”) and minimum (“L”) revolutions, as well as idle (“T”). In order to exclude unwanted intervention by an inexperienced user in the operation of the carburetor, some manufacturers install only one idle screw.
DIY chainsaw repair, video
A chainsaw is a very useful tool that is simply irreplaceable in the household. This is a relatively simple technical tool, but its mechanisms tend to fail. The chainsaw can stall, not pick up speed at the most crucial moment, preventing the planned work from being completed. We will talk about the causes of breakdowns and troubleshooting in this article.
To understand the causes of chainsaw breakdowns, you need to understand what such a device is. It works on an ordinary two-stroke internal combustion engine, the malfunctions of which are most often the reason that the chainsaw stalls. An internal combustion engine can be naughty for various reasons, but they all lead to the same consequences. The most common consequences of breakdowns are the following:
A working chainsaw is the key to the quality of successful work
- the motor does not start;
- the motor is unstable, often stalls;
- chainsaw stalls under load.
A variety of malfunctions can be the cause of such malfunctions. The most common of these are:
- clogged air or fuel filter;
- malfunctions in the spark plug;
- carburetor malfunctions due to strong vibration of the mechanism;
- problems with the gas line;
- poor quality fuel mixture;
- dirty muffler;
- problems in the cylinder group.
Each of the possible problems should be analyzed in detail.
The chainsaw may well stall at idle if the filters installed in it become clogged. First of all, if problems arise in the operation of the tool, it is necessary to check the fuel filter: to do this, disconnect the gas line and look at how the fuel flows to the carburetor. If the fuel is supplied in normal doses, then everything is in order with the filter and the problem must be looked for elsewhere. In case of insufficient or no gasoline supply, the filter will have to be cleaned or changed.
To clean the fuel filter, you must first drain the fuel from the tank and remove the filter element from it. You need to remove the filter through the filler hole of the tank with a hook, which can be made from ordinary wire. Detach the filter from the suction hose and remove it carefully. Sometimes a clogged filter can be cleaned, but in most cases it is much easier and more expedient to purchase a new filter element, and then install it as you removed the old one.
Air filters become clogged with dirt and dust, just like fuel filters. Such problems often lead to malfunctions of the chainsaw. due to a clogged filter, the air supply to the system becomes difficult, there is too much gasoline in the air-fuel mixture, which leads to a malfunction of the device.
To clean the filter element, it must be carefully removed from the chainsaw so that the dust on it does not get into the carburetor. If it has no visible damage, it is simply thoroughly cleaned of dirt, after which it is washed using the available detergents, dried and returned to its place.
To ensure high-quality and long-term operation of the tool, professionals recommend changing the filters at least once every 3 months.
The spark plug is the most important component of the ignition system, it is recommended to change it annually, but owners often forget about this simple rule. As a result, noticeable problems appear in idle operation. There are several faults specific to the ignition system, the most common of which are:
- 1. At the time of start-up, the spark plug is poured with gasoline. It is necessary to remove the plug from the hole, dry it without igniting and drain excess gasoline from the socket. After half an hour, you can put the candle back in place and try to start the mechanism again.
- 2. Poor contact of the tip of the candle with the wire. Due to poor contact, the spark disappears and the chainsaw cannot work normally. In this case, you need to check the connection and fix the problem, if any.
- 3. Problems in the electronic ignition unit, leading to a lack of spark. If checking the tip-to-wire connection does not reveal the problem, but there is no spark, the ignition unit may be the cause. It is impossible to repair the block, if it is broken, it must be replaced with a new one.
- 4. Incorrect gap between the electrodes of the spark plug. For different candles, the distance between the electrodes is in the range of 0.2-0.5 mm. The gap is set using a feeler gauge of suitable thickness.
If the malfunction of the spark plug is not damaged, then the defect lies elsewhere. A completely dry plug indicates that the problem is related to the lack of fuel. In such a situation, you will have to carefully check the entire fuel supply system in the chainsaw to find a defect.
Husqvarna chainsaw won’t stay running.
The presence of black carbon on the plug indicates poor carburetor adjustment, oil entering the fuel, or fuel oversaturation with air. In this case, you should remove and clean the spark plug, completely replace the fuel and re-adjust the carburetor operation.
If the inspection did not reveal problems with the filter elements and the spark plug, it is possible that the device is not picking up speed due to substandard operation of the carburetor. This unit in the mechanism is responsible for supplying the required amount of air-fuel mixture to the engine, and if it is incorrectly adjusted, the chainsaw will not be able to work normally. The carburetor has three special screws that allow you to adjust its operation:
- maximum speed screw;
Some manufacturers are afraid of incompetent and inexperienced users interfering with the device, therefore they have only one screw on the carburetor. which is responsible for idling. Regardless of the number of screws, the device may only be adjusted in full accordance with the manufacturer’s instructions. If the carburetor continues to junk after adjusting to factory specifications, it is recommended to clean the unit’s air and fuel passages, filter mesh and jets. If defects are found on these elements, it is recommended to change them to new ones.
When servicing and repairing a chainsaw, it must be remembered that the carburetor is a complex assembly consisting of many parts that are easily damaged. To prevent this from happening, disassemble the carburetor slowly and carefully.
The device may not develop the speed required for operation due to a violation of the integrity of the fuel line or an inappropriate ratio of elements in the fuel mixture, which consists of oil and fuel. Before starting the mechanism, it is very important to visually check the integrity of its elements and external assemblies in order to timely detect any possible defects on the body, drips of working fluids and other evidence of malfunctions. In case of physical damage to various elements of the saw, air leaks may occur, due to which the device will not be able to work normally. Particular attention must be paid to the fuel line. a rubber pipe through which the working mixture moves.
Leaving the device in a damp place for a long time, it should be borne in mind that when the temperature drops, the fuel line may simply crack, through it it will no longer be possible to supply fuel to the working units of the chainsaw and it will have to be replaced with a new one. It is impossible to repair the fuel line in case of physical damage.
To avoid problems with the operation of mechanisms, you should properly prepare the fuel mixture. add high-quality ingredients to it in exactly the ratio indicated in the manufacturer’s instructions for your device. An incorrect ratio of the elements of the fuel mixture leads to the fact that the engine parts will not be sufficiently lubricated, due to which the device can not only stall, but also can fail, it will stop starting and it will need complex and expensive repairs.
If, when using the device, there is a noticeable drop in engine power in idle mode and the car often stalls, be sure to check its muffler. It is not uncommon for the muffler to become heavily clogged with resinous particles and various combustion products of the spark extinguisher, which settle on the walls of the device in the form of heavy deposits. The layer of such deposits can interfere with the normal exhaust gas emission and therefore should be removed periodically. To clean the muffler, it must be removed from the engine and disassembled, if disassembled at all. The holes remaining from the muffler should be plugged.
The assembly and all its constituent elements are thoroughly wiped with a cloth moistened with water with the addition of detergents. The collapsible muffler is easy to dry after cleaning. just leave it disassembled for several hours. To thoroughly dry the non-separable muffler, it is better to use a household hairdryer. It is strongly not recommended to clean the muffler with dry rags and without the use of personal protective equipment. Particles of toxic substances can enter the respiratory tract and cause significant harm to human health.
To reduce the likelihood of muffler contamination and to eliminate the need for frequent cleaning, use only high-quality oil to create a fuel mixture. It is best to use the ingredients recommended by the chainsaw manufacturer, even if they are expensive.
The problems described above are the most common, but their absence may indicate that the problem is hidden elsewhere. If the saw does not start when you press the gas, it is necessary to check the central element of the engine. the cylindrical group, because of it, the machines often work poorly.
Sometimes it is even possible to simply visually determine the malfunction of the cylinder-piston group of the engine. The presence of such visible defects as chips, scuffs, signs of severe wear are clear indications that the chainsaw does not work precisely because of problems with the cylinder. Physical damage and wear is the reason to change the cylinder, since it will not be possible to repair it.
If there are no visually any problems with this element of the chainsaw, it is necessary to carefully examine its piston rings. Ring damage often results in loss of engine power and instability. If the rings run too freely in the grooves of the cylinder, it is time to replace the parts.
A complete picture of the state of the cylinder-piston group can be obtained only after disassembling the entire engine of the device. This is a very time-consuming and complex task that requires professional knowledge and experience from the contractor. It is not recommended to do such work on your own, it is better to entrust the analysis to professionals, or ask for help from a friend who understands the device of chainsaws.
Any technique can go out of order, eternal knots and parts that can serve an infinitely long time have not yet been invented. However, do not forget that proper maintenance will significantly increase the service life of any technical device, avoid breakdowns and even save your own money. Take proper care of your chainsaw, fill it with only high-quality fuel mixtures prepared according to the manufacturer’s instructions, and it will serve you for a long time.
What to do if the chainsaw stalls at idle speed
The chainsaw stalls at idle: many owners of this tool face such a problem. By its own design, the saw is a fairly light tool. But there are times when it fails. The main problem in troubleshooting is determining the correct cause of the abnormal operation. Once the cause has been identified, fixing the defect is usually quite simple.
Checking the spark plug and ignition system
According to the manufacturers’ recommendations, the spark plug should be replaced annually, regardless of the intensity of the tool use. Failure to follow these tips leads to a completely natural result: failures at idle speed, subsequent failure.
Typical defects in the ignition system are as follows:
- The candle was flooded with fuel at the time of start-up. It is necessary to remove it from the nest, dry it, if possible, blow it out with compressed air. Drain the remaining fuel from the cylinder through the mounting hole, blow it out with compressed air. Then install the candle, connect the high-voltage wire, start.
- No spark on the spark plug electrodes. You need to disconnect the high voltage wire and check for a spark on it. If the spark is normal, check the connection, eliminate any defects. The absence of a spark on the high-voltage wire indicates a malfunction of the ignition unit. This device cannot be repaired, it must be replaced with a new one.
- The gap between the spark plug electrodes is broken. This parameter for various types of devices can be in the range from 0.2 to 0.5 mm. Checking and adjusting must be carried out using a special dipstick or vernier caliper. The required value can be found in the instruction manual of the tool.
- The direction of the search can be determined by the appearance of the candle. If the spark plug turns out to be dry after several attempts to start the engine, it means that gasoline is not entering the cylinder. It is necessary to check the fuel supply system and carburetor.
- The presence of black soot or carbon deposits on the electrodes indicates an incorrect carburetor adjustment or a clogged air filter. Possibly low-quality fuel with large m of oil is being used. During normal operation of the ignition system, the electrodes have a uniform gray color and brown deposits on the insulators.