Do-it-yourself chainsaw repair won't start

In detail: repairing chainsaws with your own hands does not start from a real master for the site my.housecope.com.

The chainsaw is a worthy replacement for hand saws and axes. Today, this tool is available in almost every household - it is indispensable for setting up a personal plot, construction and repair work. Intensive use and improper care of the tool can lead to premature failure. However, the owner of the chainsaw does not have to go to the workshop right away - many of the faults that can happen to her during operation are quite realistic to eliminate on their own.

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 parts of the chainsaw.

Most often, failures 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:

Video (click to play).

do not start;
deafen;
work unstable;
overheat;
smoke;
develop insufficient power.

As for all other malfunctions, as a rule, they manifest themselves with a normally operating motor.

If your chainsaw won't start, the first thing to do is to check for a mixture of fuel in the tank. By the way, it must be prepared in the proportions indicated by the engine manufacturer, otherwise the instrument will simply not start.

After verifying that the fuel mixture is correct and available, the ignition system should be checked. To do this, you need to inspect the spark plug.

Her condition can say a lot:

indicates that the fuel mixture does not enter the carburetor, which means that the problem is not in the ignition;

is the result of an overabundance of the fuel mixture, which lies either in a violation of the engine starting algorithm or in an incorrect carburetor adjustment;

this is a signal about the presence of low-quality oil in the engine lubrication system, incorrect carburetor settings, or an incorrectly prepared fuel mixture.

If the spark plug is splashed with fuel, wipe it thoroughly after removing it. The fuel supply system should also be cleaned. To do this, it overlaps, after which the starter is turned on. A carbonized candle must be carefully cleaned with an awl and emery.

When checking the spark plugs, you should pay attention to the distance between the electrodes (the normal gap is 0.5-0.65 mm), as well as the condition of the gasket and the presence of a spark. A damaged or worn gasket will have to be replaced, and the spark can be checked by putting on the ignition cable, connecting the cylinder and plug nut, and starting the starter.

If the discharge does not occur, the plug must be replaced. In the event that a spark does not appear with a new candle, then the problem is in the connection to the high-voltage wire or in it itself.

If the fuel mixture does not flow into the cylinder, but the spark plug is working properly, this may mean that:

Clogged fuel filter.

To clean this unit, remove the fuel hose and check the jet. If it is weak, the filter must be removed through the filler hole of the fuel tank and cleaned or replaced if completely worn out.

As a preventive measure, it is recommended to replace the fuel filter at least once every 3 months.

This is nothing more than a hole in the fuel tank cap, which is cleaned out with an awl.

The fuel mixture is not supplied or is supplied insufficiently.

There may be several reasons for this:

the air filter is clogged (in this case, it must be removed, rinsed with water, dried and replaced);
the carburetor settings are out of order (which means this unit needs to be re-adjusted);
the integrity of the carburetor membrane is broken (must be replaced);
the channels of the carburetor are clogged (it must be disassembled and all parts and assemblies must be cleaned).

If at low speeds the engine of the chainsaw works normally, but at high speeds it starts to stall and smoke, the problem may be hidden in the muffler.

To check the quality of its work, you should do:

dismantling (with the obligatory closing of the outlet);
disassembly (if the muffler is collapsible);
cleaning from carbon deposits using special detergents or dry method;
drying (using a hair dryer);
reassembly and assembly.

Dry cleaning without respiratory protection is not recommended. The carcinogens present in the soot will be released into the surrounding atmosphere in the form of dust, the inhalation of which is extremely hazardous to health.

To prevent clogging of the muffler during the operation of the chainsaw, you should carefully monitor the composition of the fuel mixture and the quality of its components.

If the chainsaw engine does not start or cannot develop normal power, it is likely that sufficient pressure does not build up in the engine cylinder for combustion of the fuel mixture. The reason for this may be the wear of the elements of the cylinder-piston group - the piston, rings, bearings, etc. In order to assess the condition of this unit, it should be visually inspected, having previously removed the muffler.

For a more complete diagnosis, a compression gauge is placed in the spark plug hole of the two-stroke engine of the chainsaw. It measures the compression in the engine. Based on the results of the check, one can judge the state of the CPG, however, the exact facts can only be obtained with a complete disassembly of the unit.

If the piston is chipped or scratched, it will obviously need to be replaced. The same applies to deformed or broken piston rings - for normal engine operation, they must be completely intact and free of carbon deposits.

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 cover.
CPG wear.
Carburetor clogged.
Inability to start the engine or its spontaneous stops after starting.
Increase in fuel consumption and emissions while decreasing engine power.

Chainsaw carburetor adjustment is carried out in strict accordance with the manufacturer's instructions using three special screws, which are responsible for the maximum ("M") and minimum ("L") revolutions, as well as the idle speed of the engine ("T").In order to exclude unwanted interference by an inexperienced user with the carburetor operation, some manufacturers install only one idle screw.

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 adjustments require 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 (in this case, 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).
Work at idle speed (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.

If the diagnostics showed that everything is in order with the engine and its systems, then the cause of the malfunction should be looked for in other units of the chainsaw. The most common problems are:

failure of the starter;
improper operation of the lubrication system;
incorrect operation of the chain brake;
saw chain wear, etc.

If the cause of the tool failure is not visible to the naked eye, as is the case with the engine, it is necessary to perform a thorough diagnosis of the faults and eliminate them in accordance with the manufacturer's recommendations and safety regulations.

Almost every owner of a gasoline tool is faced with interruptions in the operation of equipment. Sometimes the situation when the chainsaw does not start can confuse even an experienced person. Despite careful operation and timely maintenance, the service life of conventional two-stroke engines, assemblies and parts has its own design limitations. In this regard, even models of the world's leading manufacturers (Husqvarna, Stihl, Makita), along with their Chinese counterparts, may malfunction at startup. There are many reasons why a tool may not start well or may not start at all. Therefore, first of all, it is necessary to diagnose the main units of the chainsaw.

Experts recommend to begin with a visual inspection of the components in order to find the reasons why the chainsaw does not start well. The algorithm of this process consists in sequential diagnostics of all key elements of the internal combustion engine. To do this, you need to check:

Why does a chainsaw start badly?

The presence of a spark between the electrodes of the candle;
Gap between ignition module and flywheel with magnet;
Condition of the fuel and air filters;
Fuel mixture supply;
Correctness of the carburetor setting;
Breather (small hole) of the fuel filler cap;
The performance of the exhaust system.

Optimum spark plug gap

Professionals are sure that the presence or absence of a spark in the spark plug is a kind of indicator of the state of the fuel system, clogged air filter or incorrect portions of gasoline and oil when preparing the working mixture.All such malfunctions contribute to the formation of black carbon deposits on the central and side electrodes, which in turn leads to a decrease in the gap. To check the discharge, it is necessary to unscrew the candle from the cylinder channel and, after putting on the high-voltage wire, make several jerks with the starter. If a spark is present, then you can simply, if necessary, set the recommended distance between the contacts and wrap the spark plug back into the cylinder.

It must be remembered that the optimal gap for the spark plug electrodes may vary from manufacturer to manufacturer. Basically, this distance varies from 0.2 to 0.5 mm.

In the absence of a discharge on the spark plug and, as a result, startup problems or unstable operation of the internal combustion engine can be caused by the following malfunctions:

Excessive overflow of fuel in the spark plug channel;
Malfunction of the ignition system;
Lack of contact of the high-voltage cable with the spark plug core.

Carbon deposits on spark plug electrodes

If, when it is difficult to start the chainsaw, it pours a fuel mixture onto a cold candle, the following manipulations must be performed:

we unscrew the candle from the cylinder;

wipe it dry with a rag;

let the remaining fuel mixture evaporate for 15-30 minutes;

we clean the contacts from carbon deposits with sandpaper;

set in a candle in a channel.

In most cases, this algorithm helps to start the engine, but does not allow determining the reasons why the chainsaw does not start after the ignition is turned off. If there is no contact between the ignition wire and the spark plug, check the reliability of the connection. For these works, you can use a conventional tester. However, if the diagnostics of the wire and spark plug did not show any deviations, then most likely the problem lies in the ignition module. The coil cannot be repaired and restored, therefore it will need to be completely replaced.

Ignition module and flywheel

The distance between the ignition coil and the magnet directly affects the spark quality of the spark plug electrodes. When diagnosing faults, it will not be superfluous to check this gap, the value of which depends on the manufacturer of the chainsaw and the model. If it deviates from the norm, it is necessary to loosen the two screws of the module, and set the correct distance using a feeler gauge.

Read also: Vaz 2104 starter DIY repair

If the diagnostics of the ignition system showed no deviations, and the chainsaw starts up and immediately stalls, then you need to pay attention to the fuel supply system. First of all, you need to check the presence of a mixture in the tank and the tightness of the connection of the pipes. When disconnecting the hose from the carburetor, we make several strokes with the primer. An intermittent supply of the mixture recommended by the manufacturer will be considered the norm.

One of the reasons for unstable engine operation can be the poor quality of the fuel mixture. Experts recommend to drain gasoline from the tank during long breaks in work (more than 2 weeks)... This is because the fuel mixture can react with the plastic, resulting in carbon deposits on the spark plug.

Chainsaw fuel filter

The filter elements can have a direct impact on the quality of the air / fuel mixture. If one of the two is clogged, the recommended mixing process for air or gasoline may be disrupted. To diagnose the fuel filter of the chainsaw, you need to disconnect the pipe from the carburetor and pump it up several times. Weak pressure may indicate a clogged filter located directly in the tank. You can remove it with an ordinary wire or a screwdriver, and then replace it with a new one.

If the air filter is dirty, unstable operation of the internal combustion engine is possible both at idle and at high speeds. To clean it, you need to carefully detach the cartridge and rinse it in water and detergents. In case of severe wear, the specialists recommend replacing the filter.When dismantling and installing, you must be extremely careful and careful, since even a small speck of dirt in the carburetor can later serve as the reason why the chainsaw does not start well or stalls with increasing speed.

The breather located near the fuel tank cap serves to equalize the pressure required for optimal fuel flow and prevents fuel from flowing out of the tank. Over time, this small hole can become clogged due to high dust content, the ingress of fine sawdust, dirt. As a result, a vacuum (negative pressure) is formed inside the container, which does not allow the fuel mixture to flow out.

To unclog the breather, you need a regular sewing needle to remove dirt from the hole. Then you can remove the remaining particles with a strong jet of compressed air from the compressor.

Chainsaw muffler assy

Often one of the reasons why the chainsaw does not start is a blockage in the muffler or in the exhaust duct. In addition to the difficult start, this malfunction is accompanied by a significant drop in the power of the unit. The clogging of the exhaust system occurs most often due to poor-quality fuel or an excess of the portion of oil in the fuel mixture. To restore the functioning of the exhaust system, you will need to perform the following work:

Dismantle the muffler with a gasket;
Unscrew the spark arrester and disassemble the resonator housing;
We place the parts in a washing solution for several hours;
We dry and assemble the chainsaw exhaust system.

In most cases, the initial inspection described above will identify a malfunction that is making it difficult to start the tool. If such diagnostics did not give positive results, then it is necessary to check the compression in the cylinder, adjust the carburetor. The wear of the piston group negatively affects the start of the chainsaw on a cold one, and a poorly tuned fuel system can cause unstable operation of the chainsaw in all modes.

Amateur and professional chainsaws are complex devices. The service life of their two-stroke engines, components and assemblies has its own limitations. For this reason, quite reliable and expensive tools, along with cheap Chinese units, periodically fail and refuse to start. The situation when the chainsaw does not start or stalls is not very pleasant and sometimes confuses the user. How to identify and correct a malfunction by returning the instrument to operability.To determine the reason why the chainsaw does not start or stalls when starting, it is necessary to troubleshoot the tool. The essence of the procedure is to consistently inspect the condition and operation of the main working elements of the saw motor. At this stage, we check:

Spark plug present;

Fuel supply;

Filter status;

The operation of the breather of the stalling unit built into the fuel cap;

Functioning of the outlet channel.

back to content ↑The first step in looking for reasons why your gasoline saw won't start is to check for the spark on the spark plug. There are many factors that affect the performance of this element. However, the main ones at the initial stage of instrument troubleshooting are:

Incorrect carburetor adjustment;

The presence of more than it should be, the amount of oil in gasoline;

Clogged air filter.

All of them contribute to the formation of carbon deposits on the spark plug electrodes. In 50 cases out of 100, saws do not start on a cold one due to the absence of a spark due to carbon deposits on the electrodes and their corrosion. As a result, the gap either decreases or increases.Checking the spark plug with an idle chainsawIt is quite easy to check for a spark. This will require:

Remove the tip of the high-voltage wire;

Unscrew the candle;

Put the tip back on;

Lean the candle with a skirt against the cylinder;

Start with a starter.

If a good spark is observed between the electrodes at the time the chainsaw engine starts, then everything is in order with the ignition unit. If it is not there, then it is worth cleaning the element itself and checking the gap of the electrodes. If necessary, use a special probe to adjust the distance between the contacts.For candles from different manufacturers, the distance between the electrodes may fluctuate. For some, it may be equal to 0.5 mm. Others have 0.2 mm. Therefore, carefully study the manufacturer's recommendations.There may be no spark on the spark plug for other reasons. Of the main faults that affect the poor start of the chainsaw and the unstable operation of the internal combustion engine at idle, from which the tool can stall, the following can be attributed:

Overflow of the spark plug channel with fuel;

Lack of contact between the high-voltage cradle and the tip of the candle;

Failure of the ignition unit.

How to start a cold chainsaw if the spark plug channel is constantly flooding with gasoline? To eliminate the problem while starting the tool, you can use the following algorithm:

Unscrew the candle with a special key;

Wipe it with a clean and dry cloth;

Dry for 20 ... 30 minutes;

Remove carbon deposits with a file and adjust the gap between the electrodes;

Drain the remaining fuel from the spark plug channel and dry it;

Collect everything and try to start the mechanism.

As a rule, these measures are enough to start the chainsaw and get the job done. However, this last resort does not eliminate the main reason why the engine does not start or stalls - improper operation of the carburetor, which needs fine adjustment. If there is no spark and poor contact of the high-voltage cradle with the spark plug tip, check the connection. The check can be done using a conventional tester. If a defect is found and it is eliminated, the chainsaw should start without any problems.If the check showed that the contact is reliable, and the saw does not start further, look for the cause in the ignition unit. As a rule, a faulty unit cannot be repaired or restored. A complete replacement is required here.First you need to make sure that there is a fuel mixture in the tank of a chainsaw that does not want to start, and it regularly enters the carburetor. With a full tank, we check how the mixture is fed through the gas line. We disconnect the fuel system pipe from the carburetor and try to pump it up. In the case of a complete order, when pumping up, gasoline will be supplied in jerks in accordance with the norms set by the manufacturer. Poor or no fuel supply can result from:

The fuel supply channel is clogged;

Debris-clogged fuel filter.

Often the reason for a poor start of the chainsaw can be a tank that is too full. In this case, you should pay attention to the presence of smudges under the saw case cover. If present, refer to the connection of the gasoline feed pipe to the carburetor. Most often, it is squeezed out by pressure when the tank cap is screwed on, filled up to the very neck, which prevents the engine from starting.The quality of the fuel mixture can also be one of the reasons why the chainsaw does not start. If, after completing the work, the remaining gasoline is not drained, and the tool is left for long-term storage (more than 2 weeks), then the processes of resinification and polymerization of the components will begin to occur inside the tank. What can cause carbon deposits on the piston, rings and cylinder liner. Therefore, always prepare the mixture only in the required amount before work.If everything is in order with the fuel quality, the chainsaw engine may not start due to clogged fuel and air filters. To diagnose these elements, it will be necessary to perform a number of manipulations associated with their dismantling.

Disconnect the gasoline supply channel from the carburetor;

Pump up fuel.

If there is little or no pressure in the branch pipe, disconnect the filter. Before this, free the tank from the mixture and remove the filter element itself. Dismantling is done with a wire hook. A clogged replacement cartridge that causes a poor starting of the chainsaw engine can be cleaned, but it is best to replace it with a new one. When using the tool in dusty conditions, it should be cleaned on a regular basis.A clogged air filter can cause the chainsaw engine to malfunction, stalling or difficult to start. Dust and dirt deposited on the adsorbent material impede the flow of air into the system, make the fuel mixture so rich that it will sometimes be difficult to start the tool.Checking the air filter is one of the first steps in finding the cause of a poor start.Care should be taken when removing the air filter, as dust accumulated on the surface of the saw during operation can enter the carburetor. And this is fraught with more expensive repairs. After detaching the cartridge, thoroughly clean it of accumulated dirt and rinse it with the addition of detergent. Dry the element and place it in place just as carefully.The breather is another element, from the improper operation of which the chainsaw may not start or stall during the sawing process. This element is located on the fuel tank cap in the area of the air hole. This is a kind of valve that prevents gasoline from flowing out and equalizes the air pressure required for the free flow of fuel into the carburetor.If the breather is dirty, the working chainsaw stalls, and when it starts, it refuses to start. The thing is that air stops flowing through the hole. As a result, a negative pressure (vacuum) is created inside the fuel tank, preventing the flow of gasoline to the carburetor.Defining the problem is pretty straightforward. Disconnect the fuel hose from the carburetor and see what happens to the gasoline. If it flows out freely in a good trickle, then everything is in order with the breather. If it is absent or it flows weakly and intermittently, then the reason is identified - the breather is clogged with dirt. You can solve the problem by cleaning the air hole with a regular needle or a powerful jet of compressed air.One of the reasons that a chainsaw does not start well may be a clogged exhaust channel or its muffler. At the same time, a drop in power is noted in the process of sawing sawn timber and logs. This is most often due to resinous deposits on the spark arrestor or muffler channel, which are formed during the combustion of a poor-quality mixture of gasoline and oil, which impedes the removal of exhaust gases.Resonator clogged with carbon deposits can cause poor starting of the gasoline saw.Eliminate the cause of the poor start of the chainsaw, in this case, you can remove the accumulated combustion products. To do this, perform a number of manipulations:

Remove the muffler by unscrewing the screws;

Remove the cooling panel and gasket;

Remove the spark arrestor;

Disassemble the resonator housing;

Wash all elements from carbon deposits with a detergent;

Let them dry completely;

Collect everything in reverse order;

To prevent dust and sand from entering the cylinder when cleaning the muffler, cover the outlet of the chainsaw engine with a clean rag. If the initial inspection did not give anything or the defects were eliminated during the search, and the chainsaw does not start further, then you need to look for more serious reasons. It is best to identify and eliminate such breakdowns in a service center. However, with experience, you can find and eliminate them yourself. What to diagnose and check?

Compression in the cylinder;

Compression in the crankcase;

Carburetor work.

In the first case, checking the compression in the cylinder will allow you to find out the state of the cylinder-piston group (CPG) of a chainsaw that does not want to start cold. For this you need a compressometer. The device is screwed into place of the spark plug and the engine is idle. Measurement of readings allows you to judge the state of the CPG. In the absence of a compression gauge, the compression in the cylinder can be determined offhand as follows:

Place your finger on the candle hole;

Try starting your chainsaw engine.

By placing your finger on the spark plug hole and pulling the starter, you can check the compression in the cylinder.If you feel that your finger is pulling strongly into the candle channel, then everything is in order with the compression. The absence of a vacuum in the chamber indicates a malfunction. The cylinder-piston group needs a more detailed inspection, which will give an idea of the condition of the piston and cylinder, piston rings and bearings.The chainsaw may not start on a cold one due to the lack of compression in the engine crankcase. The main reason for this is damage to the gasket placed between the cylinder and the crankcase. It is quite easy to detect the lack of compression:

Disconnect the upper tube from the carburetor;

Pour gasoline into a regular cork;

We immerse the removed tube in the fuel;

We pull the starter several times.

If the fuel from the cap is sucked in when starting the chainsaw starter, then everything is in order with the compression. If not, see the gasket.If the fuel is drawn in, then everything is in order - the gasket is intact. Otherwise, you will have to purchase a repair kit and replace it. How to do this watch the video why the Chinese chainsaw does not start: