The chainsaw stalls at idle speed: many owners of this tool face this problem. In terms of its design, the saw is a fairly simple tool. But there are times when it fails. The main problem in troubleshooting is determining the correct cause of abnormal operation . Once the cause is identified, eliminating the defect is usually quite simple.
Circuit diagram of a chainsaw.
Probable reasons for failure
The power unit of all chainsaws is a single-cylinder internal combustion engine. Devices of this type are characterized by such malfunctions as violations of intra-cylinder compression, changes in the fuel mixture ratio, incorrect ignition operation, and low-quality fuels and lubricants. The main problems in the operation of the power unit are the following:
- the engine runs stably at minimum speeds, but stalls when the speed increases;
- the start-up occurs normally, but the idle speed is unstable and stalls quickly;
- won't start.
Electronic ignition circuit for a chainsaw.
Abnormal idle operation can be caused by various reasons. They can be divided into several positions:
- reduced filter capacity (gasoline and air);
- abnormal operation of the ignition system:
- the carburetor settings changed spontaneously;
- malfunction of fuel line elements;
- exhaust channels and muffler are clogged;
- defects of the piston, cylinder, valves.
Repairs should begin with an external inspection and checking the presence of fuel in the tank.
Why do chainsaws stand still when hot?
The situation when a chainsaw starts in the cold and can be delayed while heating is familiar to many who encounter them. The main reasons for this behavior of the saw are the following.
- Faulty ignition module (coil). The malfunction can be determined by checking the spark first on a cold engine and then on a hot one. If there is no spark when the engine is hot, try to solve the problem by replacing the ignition coil.
- The chainsaw carburetor is not set correctly (spark plug is firing too hot). The problem can be identified by the way the saw is placed in the cold. If you don't have to close the choke for a cold start and the engine starts without a previous flash, the fuel mixture is not formed properly and after the engine warms up, the fuel fills the spark plug and makes starting impossible. The problem was resolved by adjusting the carburetor.
- Faulty spark plug. In this situation, as in a faulty ignition coil, the spark disappears when the engine warms up. You should try replacing the spark plug with a new one, and if that doesn't help, you should check the ignition coil and the clearance between it and the flywheel.
Checking and repairing filters
The engine may run rough or stall if there is not enough fuel or air. Causes: clogged air or fuel filter. To check the fuel filter, you need to remove the fuel line hose from the carburetor fitting and direct it into a container. Then press the fuel pump several times. If the fuel is pumped normally, in clearly defined doses, without dirt, then the fuel filter is working properly. If the stream is weak or fuel is not pumped at all, the filter needs to be replaced or, if possible, cleaned.
Clogging of the fuel filter with sawdust is one of the reasons for chainsaw failure.
The device must be removed from the fuel tank (after draining all the fuel from it). On most models, the fuel filter can be pulled out with a wire hook through the neck. If the filter design is dismountable and can be cleaned, it must be disassembled and washed in accordance with the manufacturer’s recommendations. Otherwise, replace it with a new filter.
Similar problems can arise when the air filter is clogged with dust, sawdust, or dirt. If there is insufficient air, the fuel mixture will be enriched and the fuel combustion process will be difficult.
To check, remove the filter. During operation, precautions must be taken to prevent dust from entering the carburetor. The device must be cleaned and rinsed in warm water with added detergent. After drying, if possible, blow with low-pressure compressed air and reinstall. If the chainsaw works normally, then the cause has been eliminated; if not, you need to look further.
If the tool is used continuously, it is recommended to replace the filters of the fuel and air systems after 3 months.
Briefly about the main thing
A chainsaw is not a necessary tool in the household, but it greatly simplifies life in various situations. It is easy to use and easy to maintain, but at times the saw may stop working.
I've had problems several times. The first time, I, still an inexperienced master, mixed gasoline and oil in the wrong proportions and filled the spark plugs. I had to replace them completely because I bent the contacts while cleaning them. In the second, the chainsaw suddenly began to stall when heating up. I had to check the muffler and carburetor, then review all the gaskets and seals, and replace one of them.
I would like to give a little advice to everyone who has just started working with a chainsaw. If a problem arises, you should first check the oil and gasoline levels, the proportions of the fuel mixture, and only then climb inside. You also need to store the tool properly (be sure to drain the oil and gasoline for the winter) and regularly check it before use.
Checking the spark plug and ignition system
According to manufacturers' recommendations, the spark plug should be changed annually, regardless of the intensity of use of the tool. Failure to follow these tips leads to a completely natural result: failures at idle speed and subsequent failure.
Typical ignition system defects are as follows:
Faulty chainsaw spark plugs.
- The spark plug was filled with fuel at the time of start-up. It is necessary to remove it from the socket, dry it, and, if possible, blow it with compressed air. Drain the remaining fuel from the cylinder through the installation hole and blow it out with compressed air. Then install the spark plug, connect the high-voltage wire, and start it.
- No spark at 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 and eliminate any defects found. 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 different types of devices can range from 0.2 to 0.5 mm. Checking and adjustments must be performed using a special probe or caliper. The required value can be found in the operating instructions for the tool.
- By the appearance of the candle, you can determine the direction of the search. 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 incorrect carburetor adjustment or a clogged air filter. Possibly low-quality fuel with a high oil content is used. During normal operation of the ignition system, the electrodes have a uniform gray color and a brown coating on the insulators.
Why does a chainsaw stall when heating up?
The situation in which a chainsaw starts up when cold, but may stall while warming up, is familiar to many who deal with them. The main reasons for this behavior of the saw are as follows.
- The ignition module (coil) is faulty. You can determine the malfunction by checking the spark first on a cold engine, and then on a hot one. If there is no spark on a hot engine, then you should try to fix the problem by replacing the ignition coil.
- The chainsaw carburetor is not set correctly (fills the spark plug hot). You can determine the problem by how the saw starts when cold. If for a cold start it is not necessary to close the air damper, and the engine starts without a preliminary flash, then the fuel mixture is not formed correctly and after the engine warms up, the fuel floods the spark plug and makes starting impossible. The problem is eliminated by adjusting the carburetor.
- The spark plug is faulty. In such a situation, similar to a faulty ignition coil, the spark disappears when the engine heats up. It is worth trying to replace the spark plug with a new one, and if this does not help, then you need to check the ignition coil and the gap between it and the flywheel.
You can check the ignition coil using a multimeter or by replacing it with a known good one. Checking the primary and secondary windings with a multimeter is carried out in resistance measurement mode. The resistance of the primary winding, the working coil, is 1 kOhm - the secondary is 4 kOhm.
Carburetor check and repair
The operating principle of a chainsaw carburetor.
If checking the ignition system, fuel filters, and muffler did not produce tangible results, the tool still does not want to work normally at minimum speed, you need to check the carburetor.
To adjust the operating modes, there are three screws on the device body designed to set the minimum rotation speed, maximum speed and idle speed.
On many models, manufacturers install only the idle air adjustment screw to avoid incompetent attempts to adjust the device. In all versions of the device, adjustment must be performed exactly according to the manufacturers' recommendations.
If adjusting the device does not restore normal operation of the instrument, you need to completely disassemble the device and inspect it. It should be understood that a carburetor is a rather complex device; if you lack experience, it is advisable to contact specialists.
When disassembling, it is important to carefully inspect and wash all jets, air and fuel channels, and filter mesh. Damaged elements must be replaced with new ones. The jets must be cleaned with soft wire of the appropriate diameter.
It is advisable to carry out work in appropriate conditions. The carburetor contains many small parts, the loss of any of them will render the device inoperable.
Chainsaw speed
Modern chainsaws are characterized by fairly complex designs and simple operation. Regardless of the features of the tool, it is not immune to damage. Almost any malfunction can be avoided if you properly care for and use the equipment.
Problems that an operator may encounter when working with gas-powered tools:
- Not gaining momentum;
- Idle speed does not hold;
- The speed does not drop;
- The momentum picks up on its own.
In some cases, it is worth using the services of a specialist from the service center. But these problems can be eliminated with your own hands.
Muffler inspection and repair
Clogged mufflers should be left to soak in warm water and detergent, then wiped thoroughly and dried.
A malfunction of the muffler leads to a drop in the power of the tool during operation and stops in idle mode. Despite the apparent simplicity of this detail, it is also important to keep an eye on it. Quite often the muffler becomes clogged. During operation, it is possible that wood dust, sawdust, and resin particles may get on the grate. High temperatures cause them to stick and accumulate; exhaust gases also form deposits on the surfaces of the spark arrestor and other parts. The layer that increases over time reduces the throughput of the muffler and interferes with the normal removal of exhaust gases. The engine, figuratively speaking, is choking.
Repairing this unit is not difficult and is within the capabilities of many tool owners. The device should be removed from the engine, the holes should be covered with a rag or other material. If the resulting layer is too hard, all parts can be left to soak in warm water and detergent. After the plaque has softened, the parts should be washed with a rag or soft brush and wiped thoroughly. Inaccessible areas can be blown with compressed air or dried with a hairdryer. The use of mechanical means of removal is not advisable.
For normal operation of the muffler over a long period of operation, you should use lubricants recommended by the manufacturer, monitoring their expiration dates. The mixture must be prepared immediately before work and consumed completely.
The chainsaw picks up speed on its own
A problem may arise when the saw itself begins to gain speed. While working, the unit stalls, preventing you from fully using the chainsaw.
Factors that can cause unit failure:
- The carburetor, fuel or air filters are clogged;
- The fuel step is damaged or clogged;
- The leading pipe between the carburetor block and the engine cylinder has become depressurized;
- A problem with the settings of the screw (often the H-screw) of the carburetor.
The following work is performed:
- The carburetor and filters are cleaned. At the same time, the correct setting of screws L and H is controlled;
- The fuel filter should not be removed, as this will negatively affect the service life of the tool. It is enough to check whether it is ignited; the fuel supply hose should not be bent.
Problems with the operating speed of a chainsaw can arise in any situation.
Therefore, it is important to be attentive to gas-powered tools and carry out timely maintenance and diagnostics. Correct and timely work will allow you to quickly restore the working functions of the saw
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Possible faults
To get any tool working properly, you must first determine the exact cause of the failure. Let's look at the most common situations in which a chainsaw stalls.
Poor quality fuel
For trouble-free operation of the engine, the quality of the fuel used is important. To keep your saw running smoothly, it is important to use the correct fuel.
Fill the tank with gasoline with the octane rating recommended by the manufacturer.
The second important condition is choosing the right oil. When purchasing, you should give preference to products from brands that produce lubricants with special additives
The saw may stall if the proportions of gasoline and oil are not maintained during refueling. Due to lack of lubrication, the mechanisms jam and the tool stops working.
When mixing, you should use the proportions indicated in the instructions for the saw, and not the data on the oil packaging. The optimal ratio for most tool models is 25 ml of lubricant per 1 liter of gasoline.
For smooth operation of the saw, use AI-92 gasoline and two-stroke oil.
Filters are clogged
In this case, the saw runs idle, but when you press the gas it stalls. Most often this is caused by the use of low-quality gasoline. A clogged filter interferes with the flow of fuel to the engine, so the saw stops under load.
One of the important parts of the tool is the air filter. The performance of a chainsaw depends on its cleanliness and correct choice, which directly depends on the operating conditions of the tool:
- Cotton filter - installed on tools that are used with a saw in the warm season in dry air.
- The HD 2 filter is intended for use of the tool in winter or in dusty conditions (for example, during large-scale logging). Such parts are often equipped with professional tools.
Breather clogged
This small hole on the chainsaw tank is designed to allow air to enter. Depending on the model, it is located in the lid or in one of the walls. A clogged breather creates a vacuum inside the tank, which prevents fuel from entering the carburetor.
Fuel supply interrupted
A broken or damaged pipe is a possible reason why the saw stalls during operation. In this case, the tool starts up, since a small amount of fuel is present in the engine, but refuses to work further.
Storing the saw at sub-zero temperatures will cause the fuel tube to crack. The situation will be corrected only by replacing the part.
Problems with electrical components
Spark plugs are an important element of a chainsaw engine. The tool may stall if carbon deposits accumulate on their surface. Therefore, spark plugs need to be cleaned periodically and changed promptly.
Problems with the power supply can occur if the gap between the ignition coil and the magneto is damaged. This is caused by impacts when operating the saw in difficult conditions. For stable engine operation, the gap should not be more than 0.5 mm.
Expert opinion Dmitry Konstantinovich Levin
The lack of a spark may be due to a clogged fuel filter or depressurization of the tubes. If the spark plugs are wet, it means that during operation of the tool they are filled with gasoline or oil.
Carburetor not adjusted or clogged
Problems with the operation of this unit are indicated by the saw stopping at idle.
The carburetor malfunctions in the following cases:
- clogged jets, nozzles, channels or filters;
- wear of oil seals, cuffs, gaskets;
- incorrect adjustment.
Dirty muffler
The accumulation of carbon deposits in this part leads to loss of power of the tool. The muffler can become clogged if the wrong or low-quality oil is used. Adding too much lubricant to gasoline can also cause clogs.
Poorly lubricated chain
Due to clogging or damage to the oil drive, the tool tire remains dry: the chain jams and the saw stalls during operation. The same problem can arise when using low-quality oil.
