What to do if the chain saw will not start

What Keeps the Chain in Motion

The construction of this tool is based on a two-factor carburetor-type engine. Its output can vary greatly. it all depends on what the saw is intended for: if for domestic work, it will be around 4 kW, but if for felling large wood, it will be around 8-9 kW.

Top 5 Reasons A Chainsaw Won’t Start

Of course, in addition to the engine, the product has many mechanical and electronic elements, such as a quick brake, filter, oil supply system, etc.п., but it is the engine that is important to us first of all, as it is the most often the problem of stopping the chain.

The chain saw does not start. Why? Causes and avoidance.

Dirt on the chainsaw’s main filtration elements negatively affects the way the chain saw operates.

For example, a dirty air filter, will provide air to the carburetor not in full, which will affect the quality of the fuel-air mixture and the normal starting of the engine. A clogged fuel filter can make it difficult or even impossible to get gasoline to the carburetor and keep the engine running.

Reduced compression

One of the frequent cases of difficulty in starting the chainsaw is the wear of the cylinder block (piston group).

As you know, in order to start a chain saw you need to have compression in the engine. It is necessary for normal compression of the fuel mixture in the engine cylinder, it also affects the work of the gasoline pump.

During the operation of the tool the compression value will drop and the chainsaw will not start properly.

The reasons for no compression, or reduced compression, can be natural, i.e.к. The engine wears out when it is running. Also problems can be caused by a serious failure, such as a scored cylinder block or a broken piston ring.

A sign of low compression, is a weak resistance of the starter motor when starting. At low compression there is a decrease in power of chain saw, what negatively affects its performance. The problem can be eliminated by replacing piston rings or the entire cylinder head.

Adjusting the carburetor

A bad carburetor adjustment will cause the chain saw not to develop full power. The problem can be corrected by changing piston rings or the entire cylinder block. The adjustment of the carburetor directly affects the quality of the fuel-air mixture, which is necessary for normal starting and further engine operation.

If the carburetor is not properly adjusted, there will be more or less gasoline in the mixture of fuel with air than required, and the mixture will not ignite even with normal spark formation.

Excess gasoline in the mixture, is commonly referred to as overflow. A characteristic sign of an overflow is a wet spark plug, after several unsuccessful attempts to start the chainsaw.

chain, start

Spark plug

The spark plug is one of the main components of the ignition system. It is the element that creates the spark, and if that element fails, it is very difficult or even impossible to start the engine.

Spark plug may fail completely or work irregularly or give a weak spark. To check the spark plug is simple enough, you need to unscrew it from the engine, connect it to the cap of the ignition wire and, putting it on the cylinder, pull the starter. If the spark plug is okay, the spark will be powerful with a bluish tint. Weak spark with a reddish tint, a sign of a problem. Defective spark plug needs to be replaced.

Ignition coil

The ignition coil may be the reason why a new chain saw does not start, or starts poorly. Modern chain saws are equipped with electronic ignition coils. This part cannot be repaired, and as a rule, if there is a defect, it is replaced completely.

Gap between ignition coil and flywheel

A wrongly exposed gap between the flywheel and the ignition coil contacts affects the quality of ignition, which in turn is responsible for a normal start and engine stable operation.

The chain saw will not start. Why? The Causes and How to Avoid.

Your chainsaw won’t start? It can often happen at the most inopportune moment when you need to work urgently. You should agree that it is unpleasant. We must admit that chainsaws from famous manufacturers (STIHL, Husqvarna, Echo, Solo and others) do not start much less often than from Chinese producers. Today we will analyze the causes of this unpleasant event and how to avoid it. If you don’t see your reason listed above, you can ask your question in the discussions.

To begin with, you have to decide if you have a new chainsaw that won’t start or if it has been in use for a long time. This is necessary so that corrective measures can be taken.

If your new chainsaw will not start, then:

  • If it has not been 14 days since you purchased the saw, you can return it or exchange it for a new one. This is the most sensible way out of all. (When buying a chainsaw, be sure to ask the seller to start it up. This does not apply to online stores, because serious IMs always check the product before sending it to the customer.)
  • If you cannot exchange your chainsaw for objective reasons or if more than two weeks have elapsed since you purchased it, the reasons are probably quite serious. To be sure your chainsaw will not start for technical reasons, rather than because of an oversight, read the manual carefully.
  • Here’s a look at why your chainsaw won’t start, and why it’s just as good for a new chain saw as it is for a used one.

Here are the reasons a chainsaw won’t start, in this checklist.

  • Check the fuel level in the tank and its quality. It is quite logical that the chain saw will not start without fuel. So if you don’t have any fuel, fill it up. If fuel is left in the tank for an extended period of time (more than 3 weeks), drain it and fill with new. Leaking fuel with access to oxygen quickly loses its octane rating and becomes unsuitable for the chainsaw. Read more about fuel here: How to Make Gasoline for a Chainsaw? Choice of oil, proportions
  • Check the spark plug on the chain saw. First of all, whether it is filled or not. If it’s wet wipe it off, blow it out and screw it back on. Secondly, check for sparks. You can check it by unscrewing it and putting the tip on the cylinder block and pull the starter cord. If there is a spark, we go on with the reasons. Third, look at the condition of the spark plug. Read more about how to diagnose your chainsaw with spark plugs here: spark plug diagnosis.
  • Check the air and fuel filter. Severely clogged filters can prevent the chainsaw from starting. The air filter is located just under the cover on top of the chain saw. The fuel cell is in the tank. Also check the breather plug, which is also in the gas tank. The best way to diagnose is to remove them and try to run it without them.
  • It is necessary to inspect the muffler to check for soot in it. Read more about cleaning the muffler here: Cleaning your chainsaw muffler.
  • Check all hoses and connections. A loose connection or a crack in the hose is often the cause of a chainsaw not starting. You should also inspect the crankshaft oil seals.
  • Clean the carburetor. It is best to disassemble the chainsaw carburetor on an uncluttered table, laying out a clean cloth. Lay out all the spare parts separately to make assembly easier. The carburetor should be cleaned with special fluids for cleaning injectors and injectors, for example.
  • Check the ignition system. Corner might be out of alignment, handwheel could turn.
  • If the previous steps did not help and the chain saw is still not working, you may need to adjust the carburetor. Adjusting the carburetor on any chain saw is similar to the above link. The only exception is STIHL chain saws, which have only one idle speed adjustment screw.
  • The worst situation is when none of the above measures helped. You may need to replace the cylinder block (piston group). There are three ways to check this: 1.If the piston does not move in the cylinder, it is definitely better to replace the cylinder head. Of course you can put a new piston or bore the cylinder, but it will not produce the same result as when a new cylinder head is installed. 2.To disassemble the chainsaw and perform a visual inspection. 3.Remove the muffler and look at the exposed part.
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You can help the chainsaw rating by voting in the poll: Rating chainsaws

How to Properly Start a Chainsaw?

Before you start the tool, you need to read its manual. The instructions for some models indicate that before starting the saw, the inertia brake of the instantaneous chain stop should be engaged. It is therefore safer for the operator to start. But when the brake is on it will be harder to start the STIHL chain saw. In practice it is best to start the saw with the brake off, but always with safety in mind.

To properly start a cold chain saw, you need to stick to this order of actions:

  • The first step is to move the throttle control to the lowest position. Note that you can only move the lever into this position when the throttle lever is depressed. This will close the throttle of the carburetor. To proceed further, the throttle lever must be locked in the depressed position;
  • Then pull the starter rope several times sharply. Do this until the engine starts and then stalls. Next, the choke position lever must be moved one position up;
  • Then pull the starter rope again sharply;
  • Then briefly pull the throttle trigger and release it. The choke control lever will move automatically to its operating position. The engine rpm will drop, indicating that the chainsaw is ready for further use.

To hot start the engine, move the choke control lever to the middle position and pull the starter rope infrequently.

The main reasons why your chain saw won’t start or stops and how to fix them

There are several different reasons for a chainsaw not starting: the device may be defective, there may not be enough fuel, a malfunction in the fuel supply. Often it is possible to fix the problem with your own hands. In some cases you may need an expert to help.

Your chain saw won’t turn on hot

In those cases when the chainsaw does not start on hot, it is necessary to carry out a visual inspection of all the main nodes of the chainsaw. The inspection should begin with the spark plug. Check the spark, examine the surface of the electrode of the plug, these actions will help establish the direction in which to look for the problem.

Faults in the ignition system

If when inspecting the plug, it is found that it is wet and spark formation on the contacts does not occur, it means that the problem should be sought in the ignition system, inspect the coil, check the gap between the flywheel and coil contacts. You can also check how firmly the cap of the high-voltage wire sits on the spark plug, and the plug itself. Try to replace it with a new one.

Problems in the fuel system

If the visual inspection revealed that the spark is alive and the spark plug is dry, it means that there is a problem in the fuel system. To check it you start with the fuel filter. Next, you need to check the fuel hose and its connection to the carburetor, pay attention to the leakage of fuel from the carburetor and the presence of gasoline in the air filter housing. Begin removal of the carburetor is advisable only if a visual inspection did not allow to determine the cause of the failure.


A symptom of a problem in the fuel system is an excessive amount of fuel in the engine cylinder. As a rule, the signs of it are excessively wet spark plugs and the presence of spark on the plug pins. In this situation, you need to turn the chainsaw upside down so that the spark plug hole is pointing down. If it leaks, it means that the chainsaw won’t start because the fuel is overflowing into the engine.

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Fueling, sometimes due to improper carburetor adjustment or malfunction.

With the process of adjusting the carburetor, you can get acquainted with the example of Champion 254 saw, watching a video instruction.

Why chainsaws don’t start? Frequent malfunctions and solutions

Chainsaws are simple in design and reliable in operation.

If treated properly, they rarely malfunction and can be fixed quickly if the owner knows where to look for the cause.

And yet the question of why the chainsaw won’t start can’t be answered unequivocally. This tool is basically a conventional two-stroke combustion engine. Four conditions are necessary for its normal operation: fuel, air, spark, and lubricant.

The carburetor is responsible for the air-fuel mixture, the air is cleaned from dust by the filter, the spark is created by the ignition unit and the spark plug, and the lubricant is in the gasoline.

The reasons why the chain saw refuses to start should be sought in series, starting with simple ones and going to more complex ones. Whoever rushes to disassemble the carburetor immediately, when chain saw starts badly when hot, takes a big risk. It is better to have this unit repaired and adjusted in a specialized workshop, not by hand.

By the way, some chainsaw manufacturers make jets non-adjustable, to keep users from getting into the carburetor to change the fuel mixture.

For the trouble-free operation of the chainsaw, you need to pay special attention to the fuel. If the fuel mixture is improperly mixed, even a reliable Husqvarna will not start. In this case, the owner will start looking for the cause of malfunction anywhere, but not in the fuel. To avoid this factor, you should always prepare a fuel mix of high-quality gasoline and that brand of oil that is specified in the manual.

It should be made in such a quantity that in 1-2 weeks it will be completely exhausted. If you keep it in the can for a month, the gasoline will lose its octane qualities and you are guaranteed to have problems with the operation of the saw.

Quite often malfunctions of chainsaws occur because of the flooding of the spark plug with gasoline at start. This problem is eliminated by turning out and drying the plug (without burning!) You drain the excess fuel through the spark plug hole, then take a 20-30 minute break and put the spark plug back on and restart. A good owner always has new spark plugs in stock so that when searching for trouble to exclude this part from the list of suspects.

Lack of spark is often caused not only by plug failure, but also by poor contact between its tip and the high-voltage wire. If this connection doesn’t look suspicious but there is no spark when you turn on the starter, it is the fault of the electronic block. This assembly is not repaired, but replaced with a new one.

Remember that the inspection of the spark plug provides important information. If it is dry, it means that the cylinder does not receive fuel and you need to check the entire chain of its supply, starting from the carburetor. Black fouling indicates improper adjustment of the carburetor, feeding too much fuel into the mixture or overflow of oil into the gasoline.

If your chain saw starts and stops when you press the gas button, it is an indication of a bad fuel supply. The cause may be a clogged fuel filter or carburetor nozzle. The first unit can be checked and cleaned very quickly, but in the second case, it is better to trust the professionals.

Disassembling and cleaning the carburetor of a chainsaw requires experience and accuracy. Therefore, it is usually taken only by those owners who have already repeatedly and successfully performed this procedure.

Pay attention to the air filter too, so you don’t have to look in the wrong direction for the chainsaw malfunction. If it is clogged with dust, you will not get a good start and stable performance.

Each model of chainsaws has its own characteristic and easily correctable malfunctions. Therefore, do not rush with disassembly and repair, but rather read the reviews of owners on the forums. For example, STIHL chain saws may not start because the breather plug is clogged.

This valve equalizes the pressure in the tank with the flow of fuel. When it is clogged, a vacuum is formed in the tank and the fuel stops flowing into the carburetor. This disease is cured by cleaning the breather plug with an ordinary sewing needle.

To exclude the breather from the list of suspects is not difficult. To do this, disconnect the fuel hose from the carburetor and see if the fuel flows from it. When the gasoline flows in a full stream of the breather is clean, if the fuel from the gasoline line does not flow or flows very slowly, then the cause of the malfunction is established.

Many owners of new STIHL chain saws are worried about the idle speed after the first tank of juice. Experts think this is normal behavior and indicates that the engine and carburetor are running in good condition. Don’t rush to the service, just turn down the engine speed a little with the carburetor idle speed screw.

If the power has dropped and the chainsaw stalls when idling, don’t forget to check the muffler, which may be clogged with tarry exhaust deposits. Cleaning the exhaust port and muffler fixes these problems.

Especially unpleasant for the owner, when all the possible causes seem to be eliminated: a new serviceable spark plug is installed, the carburetor is carefully and correctly cleaned, the fuel is normal, but the chainsaw still does not want to start.

Chainsaw Won’t Start (Easily Fixed) Must See!

In this case you need to take a look at the cylinder-piston group. A visual inspection of the cylinder and piston in this case helps to find the cause. If you see chips or nicks on them, the saw will work properly only after replacing these parts. This problem can be eliminated by boring the cylinder to fit a new piston of the correct size.

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If there are no visible defects on the cylinder and piston, the piston rings are checked. To do this, the piston is inserted into the cylinder and the connecting rod is jiggled gently. If you can feel the play, it means that the rings are worn out and need to be replaced.

Chain saw failures are often caused by inadequate chain lubrication due to leaking oil lines and clogged ducts. Therefore, if the chain has become dry, you need to urgently clean the channels that supply oil to the bus. Then inspect the tube connections to the oil pump fittings. If it is found that oil is leaking heavily from the contact points or there are cracks in the oil duct, the tubes are replaced and the joints are sealed with a quality sealant.

Some chain saw parts must be replaced after the piston has reached the end of its service life. That’s why don’t forget to look in the manual where it is clearly written out. Such parts include guide bar, drive sprocket, chain, parts of antivibration system.

If the replacement is not made in time, the wear of these nodes will adversely affect the serviceable parts of the chainsaw. For example, long delays in replacing the drive sprocket lead to increased vibration that quickly breaks the crankshaft bearings.

Therefore, it is necessary to regularly check the depth of tooth wear, which should not exceed 0.5 mm. A guide bar usually lasts only 3 or 4 chains, after which it must be replaced as well.

Why the spark plug fills in the chainsaw

There are several reasons for this situation. In most cases, they are associated with improper operation of the fuel system, less often with a defect in the plug itself or ignition system malfunctions. Products are sold with factory preset components. That’s why you should not adjust the carburetor and the ignition system right away. Most likely the user did not read the manual or follow its instructions.

The manufacturer recommends that the choke shutter be closed when starting the chain saw. But this does not mean that in this state the engine will run. Stop turning the hand starter when you see the first exhaust. After that the choke should be opened. If you do not do this and keep turning the starter will flood the spark plug, and the unburned mixture will collect in the crankcase.

The spark plug on the chainsaw can fill up after a few years of good repair. In this case the cause is the failure of the control diaphragm of the fuel cell. low-quality material of the part in prolonged contact with petrol loses elasticity and the needle, responsible for fuel supply, remains in the open position.

During operation of the tool, vibrations occur, which lead to changes in adjustments. It creates a rich mixture, which is not completely combusted and partially settles on the electrodes of the spark plug. This causes the engine to malfunction and then to stop.

Almost all tools, both foreign (Husqvarna, Makita, STIHL, Partner 350), and Chinese chain saws, and domestic (Druzhba, Ural) are arranged similarly. Therefore, finding the reason why the machine won’t start and stalls isn’t very difficult.

There are four elements in which problems can occur:

chain, start
  • The fuel, for which the carburetor is responsible;
  • Lubrication;
  • The air that comes in through the air filter;
  • The spark, the quality of which depends on the ignition unit.

They all depend on each other and interact with each other. If any element is not working properly, the saw stops working.

To begin with, all tools start differently. when hot and when cold. Two frequently used mechanisms are responsible for this process.

Be sure to look at what’s written in the owner’s manual. It says to make sure that the Emergency Stop Brake is engaged when starting the engine. But it is much more difficult to start the saw with a brake, so sometimes it is better not to turn on the brake.

As you can learn from the manual, the fuel tank and the engine are inside the body, and the saw part (bar with chain), the handle and the starter are outside.

First you have to find out how the tool doesn’t start. For example, the saw starts, but immediately stops working, or loses power, the quality of the cut.

It is possible that malfunctions occur due to problems in the engine. But I would not recommend to take it apart right away. It is better to look for the problem from the simplest variant.

It is very important to consider the quality of the fuel. If the mixture is not properly prepared or has deteriorated over time, even such reliable tools as the Ural or Husqvarna 145, will not work. The manual is sure to indicate the proportions and special oil specifically for your chainsaw.

Another common problem. during the start the user fills the spark plug. It should be inspected, if it is completely dry, it means that the fuel does not flow into the cylinder.

If you see black soot or a lot of fuel, it is possible that the carburetor does not properly regulate the fuel supply.

Chainsaw won’t start

If your saw fails to start but immediately stops, the problem might be the carburetor nozzle or the fuel filter. They might be clogged.

To check if the breather plug is damaged, disconnect the fuel hose from the carburetor and see if fuel mixture is leaking.

chain, start

If your saw won’t start when hot, the problem may be in the muffler. Sometimes it gets clogged from the exhaust itself.

Quite often chain lubrication is the reason why the saw breaks down. This can happen if the ducts are clogged or the oil line is leaking.

Also inspect the tube connections to the oil pump fittings, whether they are leaking.

It’s very bad if the failure is in the cylinder. When examining it, you can find bumps or chips, that can be the cause of the problem.

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