Petrol Cutter Malfunctions

How is the repair of petrol cutters carried out? What is a brushcutter? How difficult is the repair of a petrol cutter? What are the main malfunctions of gasoline trimmers and how to fix them yourself? What to do if the brushcutter stalls when switched on? Why does he fill a candle on a brushcutter?

Symptoms of common problems

Knowing the internal structure of the brushcutter and the principle of its operation, you can easily troubleshoot with your own hands. Some breakdowns are most common and are distinguished as the main ones.

  • Engine faults should be looked for if the brushcutter does not work or does not even start. You should also pay attention to this part of the braid if unusual noises are heard during operation or strong vibration is felt. A clogged air filter can also cause engine problems.
Petrol Cutter Malfunctions
  • If fuel does not enter the combustion chamber, then you should look for the cause in the clogged fuel filter. It is also worth looking at if the tool does not run at low speeds.
  • There is no spark. This is not uncommon when the spark plug is flooded with fuel.
  • The brushcutter bar vibrates strongly, making it more difficult to work with it.
  • The reducer gets too hot in a short time, which is felt during the operation of the scythe.
  • At low rpms, the line turns poorly, which affects performance.
  • The starter grille is clogged causing the engine to overheat and stop working. The starter motor can also fail when the cord breaks when starting too abruptly.
  • Carburetor clogging may be due to the use of low quality fuel. It is also important to pay attention to the carburetor in time if the mixture is flowing.
  • The petrol cutter stalls after shutdown if the carburetor is incorrectly set.

The maintenance of a personal plot or an adjoining territory is not complete without the help of a petrol cutter. In the warm season, this tool gets the maximum work. Before you start using the brushcutter, you should prepare it correctly. It is also important to monitor the serviceability of the tool and fix breakdowns in time. You can deal with the most common malfunctions on your own by learning a little more about the petrol cutter.


It is best to start repairing a petrol brush with a step-by-step check of the main components. The first thing to check is the fuel in the tank, as well as the presence of lubricants on the main components of the tool. It is also important to know what quality and what proportion of fuel and oil used. If something goes wrong, the piston system can fail, and replacement is expensive.

Next, it is worth assessing the serviceability and performance of the spark plugs. The result is judged by the presence of a spark when there is contact with the tool body. If the fault is in the plug, then you need to remove the voltage wire from it.

In case of contamination, it is recommended to replace it with a new one and dry the candle channel. They also do this if there are cracks or chips on the candle body. The gap between the electrodes is set at 0.6 millimeters. Clamping a new candle is also done with a special key. At the end, a voltage wire must be connected to it.

Inspection of filters, both fuel and air, will be useful. If the blockages are strong, then replacing them is the best solution. You can try rinsing the air filter with water and detergent and then drying it. It is also sometimes soaked in gasoline. After drying and installing it is important to wet the filter with oil, which is used in a mixture with fuel.

It is very easy to fix the problem in the form of a stalling petrol cutter immediately after starting it is enough to adjust the carburetor according to the scheme given in the documentation. Sometimes you have to loosen the carburetor valves to make it easier to feed the mixture into it.

Sometimes the brushcutter stalls due to the intake of a large amount of air. In this case, it is necessary to increase the engine speed to release it. Also be sure to check the fuel hose for possible damage. If necessary, change it to a new one.

It is important to keep the gearbox clean and its gears should always be treated with special grease. It is worth noting that it is not always possible to repair the gearbox and starter on your own, therefore, it is more advisable to replace them with new ones if these units break.

When reducing engine power, you should pay attention to the exhaust muffler, or rather, to the mesh in it. It can become clogged with soot from burnt oil. This malfunction is solved by cleaning the mesh. This can be done using a small wire or nylon bristled brush and compressed air.

The clutch in petrol cutters can break due to wear of the pads or a broken spring. In both cases, defective parts are replaced. Sometimes the clutch becomes unusable, it can also be replaced with a new one. Over, both fully assembled couplings and separate elements for them (washer, drum, etc.) are on sale.


Petrol trimmers are simple. The main element of the tool is a two-stroke or four-stroke internal combustion engine. It is connected by means of a gearbox with a shaft that transmits the force to the cutting element. The wire connecting them is hidden in the hollow shaft. Also located next to the engine are the carburetor, air filter and starter (starter).

The motokosa mows the grass with a fishing line or knife that can rotate at a tremendous speed of 10,00013,000 revolutions per minute. The line is mounted on the trimmer head. The section of the string is from 1.5 to 3 mm. The main disadvantage of this type of cutting element is its rapid wear. As a result, you have to rewind or replace the line, sometimes this is done by changing the bobbin.

The fishing line is most often used when mowing grass, and it is better to give preference to knives (discs) to remove bushes and dense thickets. They can be of various shapes and sizes.

The blades and gearbox are covered with a protective cover, which ensures safety during work. It has special holes through which grease is supplied. To make the brushcutter easier to use, it has a belt with a fastener. It allows you to evenly distribute the weight of the unit, making it easier to work with it.

A handle is attached to the bar of the petrol cutter, on which there are buttons and levers for control. The handle can be U, D or T. For refueling brushcutters with a two-stroke engine, a mixture of gasoline and oil is used. It must be poured into the fuel tank.

General recommendations of specialists

Avoiding repairs and contributing to the long service life of the mower is a snap. The first thing to start with is familiarization with the instructions before work. It is important, when the brushcutter is in operation, to monitor how well the engine is cooled. Be sure to keep the starter and cylinder ribs clean. Otherwise, the engine can quickly deteriorate due to overheating.

Periodic engine maintenance can significantly extend the life of the brushcutter. It consists in constant inspection and cleaning of the motor. To wash a cold engine, a soft bristle brush is taken. It needs to remove dirt from the surface. And.

Fuel must not be left in the brushcutter for periods longer than 30 days. If the mower will be idle without work, it is better to drain the fuel mixture. For most tools, 92 gasoline is suitable, which in no case should be replaced with diesel fuel or gasoline with a lower octane number. It is best to use two-stroke engine oil in the mixture. It is not recommended to make fuel compositions for future use, as they eventually lose their original properties and can lead to breakage of the brushcutter.

At the end of frequent use of the spit, for example, with the arrival of late autumn, the petrol cutter should be prepared for storage. First you need to drain the fuel mixture and then start the engine. This is necessary so that the remaining mixture in the carburetor is used up. After that, the unit is thoroughly cleaned of dirt and stored. If you follow the brushcutter correctly, then even the Chinese one can show high performance for a long time.

How to repair petrol cutters, see the following.

Method 1

The first way to check the ignition coil involves the use of special equipment (stand). At home, it is not available, you can find it only in service centers.

Magneto design and operating concept

The purpose of the ignition coil is the conversion of rotational energy into a high-voltage discharge and the formation of a spark that ignites the fuel mixture. In an internal combustion engine, this part is called a magneto, since in it an alternating current is generated from the rotation of a permanent magnetic rotor or armature.

Magneto structurally consists of two windings: high and low voltage. A capacitor with breaker contacts is connected in parallel to the latter. Whereas the leads of the high voltage winding are connected to the candle and the body. They are both wound on a core, between the poles of which a rotating magnet is installed, magnetized longitudinally.

Insufficient sparking

The weak spark on the magneto is caused by a damaged capacitor. To eliminate the damage, it is necessary to replace the failed part.

Method 2

Magneto diagnostics by means of a multimeter is a solution that can be realized on your own with such a measuring device. In this case, you must do the following.

  1. Set the Meter to resistance mode and set to 200 ohms to test the primary winding.
  2. Connect the multimeter electrodes to the magneto ground and the output terminal. If the winding is intact, the resistance will vary from 0.4 to 2 ohms.
  3. Switch on the 20 kohm tester to perform a secondary diagnosis. In this case, the first probe is connected to the mass, and the second is installed in the spark plug cap. Normal values ​​are at least 4-6 com. If the circuit is damaged, the tester will show infinity, and in case of a short circuit, zero.

The exact data on what the tester should read during the primary and secondary winding check can be found in the instructions for use of the trimmer.

Unstable sparking

If the magneto sparks intermittently, the contacts must be checked first. They could be burnt or oily. The carbon deposits found are cleaned with a file, and the oil is wiped off with suede, previously soaked in gasoline. The second possible cause of the problem is the adjustment of the gap between the contacts. To eliminate it, you need to set the correct distance.

If the spark appears intermittently, it may also mean that the breaker arm pad is worn. To eliminate the malfunction, you must change the lever to a new one. In addition, the clearance should be adjusted, as with another possible cause of breakage, misalignment of the outline.

Capacitor breakdown can also be the culprit for interruptions in spark formation. In such a situation, replacement of the damaged part is required, since it is impossible to repair and recharge it.

Replacing the magneto

To remove the magneto, remove the plastic cover from the trimmer. This process is different on different brushcutter models. It is usually necessary to remove the bolts, but on some gas trimmers it may be necessary to depress the latches. After that, access to the coil opens. To remove the part, you need to unscrew the retaining fasteners and disconnect the wires.

When installing a new part, you need to correctly set the distance between the flywheel and the magneto. To do this, turn the flywheel upwards with the magnets, install the coil and secure it, but do not fully tighten the screws so that there is a small distance between the parts. Next, between the coil and the flywheel, you need to put a pocket calendar, business card or A4 paper folded in four, you can also use a plastic strip cut from a bottle. These tweaks will ensure adequate clearance between the flywheel and the magneto. A more competent solution would be to use a special template, but purchasing it for the sake of once is impractical. Next, you need to tighten the fasteners, remove the object between the parts, and, holding the magneto with your hands so that it does not spin, tighten the fixing screws tightly. After that, turn the flywheel and make sure that it does not catch the coil anywhere. Now you need to connect the wires and insert the candle into the cap, and then check the operation of the device.

Repair and lubrication of the petrol cutter gearbox

The role of the gearbox is to transfer the torque from the motor shaft to the cutting tool through 2 gears with different numbers of teeth. The torque is transmitted at an angle of 30 0. The number of revolutions of the lower cutting blade is 1.4 times less than the engine speed. Gears must be clean and lubricated. To supply oil to the teeth, there is a hole under the screw on top.

First, the place where the plug closes the hole should be cleared of soil and grass. Unscrew the plug with a suitable tool, it is included with the saw. We use a grease tube. Either a native lubricant from the manufacturer is selected, or well-known high-quality compounds, such as Oleo-Mas, Litol.24, Azmol 158. We open the protective layer of the tube and lay the instrument on its side. Slowly rotating the knife, squeeze the grease into the gear housing. The gears, turning, carry the composition with teeth over the entire surface. You can also pour grease with a special syringe.

Too little or too much lubricant can cause the gear unit to heat up. An audible knock and backlash indicate a broken bearing or dirt from a damaged boot. Bearings must be replaced using a puller, without using the heating method.

If the gearbox staggers and runs on the rod, it is necessary to replace the housing, or temporarily tighten the knot with a clamp to secure it to the pipe. If the knife stops rotating, it means that the gears do not engage; the teeth are worn out or crumbled. A pair will need to be replaced with a complete disassembly of the assembly.

When replacing the gearbox, it is necessary to select a new unit, guided by:

  • Pipe diameter;
  • The diameter of the drive shaft;
  • Section of the drive shaft;
  • Method of fastening protection

Chainsaw engine won’t start

If the mechanism does not start, immediately stalls, check sequentially:

  • Is there fuel in the tank;
  • Serviceability of the spark plug;
  • Cleanliness of the air and fuel filter;
  • The cleanliness of the breather and outlet.

It is necessary to make sure that the candle is working, it gives a spark when it comes into contact with the body. In this case, it is necessary to dry the candle channel, clean and dry the part itself. You can change the candle, but the channel must still be dried for 40 minutes. Check the health of the high-voltage wire, there may not always be a contact. A malfunction in the ignition unit when repairing a petrol cutter cannot be eliminated with your own hands.

If, when the air filter is removed, the engine does not stall, the reason is that it needs to be replaced or cleaned. Replacing the fuel filter is done with great care. Then check the cleanliness of the breather, remove the muffler mesh and clean the exhaust channel.

The next step will be to repair the carburetor, where you have to find the problem and fix it, taking into account the tiny size of the parts. If the simplest operations have not yielded results, in order not to disrupt the fine tuning of the system, it is better to entrust the repair to a specialist. Where to start diagnostics and how to properly repair petrol cutters with your own hands, check out:

Can I repair petrol cutters myself?

At first glance, a simple device for mowing grass with a two-stroke engine is fine-tuned. Repair of petrol cutters must be entrusted to a specialist or to study the technique yourself, using the operating instructions. The streamer maintenance is essential. Gearbox lubrication, line replacement, and teeth sharpening can be done on our own.

Petrol mowers malfunctions and how to fix them

Any type of petrol brush has a hollow rod, in which a connecting cable is placed between the engine shaft and the lower gearbox, which transfers rotation to the working body with the cutting tool. In the upper part there is a carburetor and a motor, at the bottom a gearbox and a working tool, covered with a casing. In the middle part there is a transverse handle in which the control buttons are located. To unload the arms, there is an unloading belt that holds the bar with the operator’s torso.

This follows, the repair of petrol cutters is to troubleshoot;

  • The engine does not start;
  • The cutting mechanism is not picking up speed;
  • The engine stalls;
  • The reducer is heated;
  • Extraneous knocking is heard, strong vibration of the bar.

Before eliminating the malfunction, you need to diagnose, determine the non-working unit.

It is important to know the lubrication points of the tool. Constant care, cleaning the device after work will extend its life. Before work, it is necessary to tighten the fastening bolts, prepare the fuel and fill the tank.

Caring for the cutting units of petrol cutters

The saw headset dulls or wears out over time. The tool becomes tense, the load increases, and the swath quality deteriorates. Metal saw blades are sharpened, plastic ones are changed.

If a fishing line is used as a cutting tool, it gradually wears out, and new material is installed in the spool. The principle of operation of the line cutter is to gradually unwind the coil under the influence of centrifugal force. On contact with the grass, the fishing line is abraded, it is fed from the reel gradually. A special winding is needed so that two cutting elements come out at the same time and do not get confused with each other.

The figure shows how to properly wind the line on the reel of the petrol cutter. Before winding a new line, you must:

  • Unscrewing the nozzle, carefully remove the cover, holding the spring with your hand;
  • Remove scraps of old fishing line from the reel;
  • Measure 5 meters of a new string and fold it in half;
  • In the coil, guides for 2 ends, hook the middle part into the recess and wind in the direction of the arrows for each half of the string;
  • Lead the remaining 20 cm through the special notches at the opposite ends of the coil;
  • Install the spring and washers, bring the ends of the line out, close the drum with a lid.

In order to better understand how to change the line on a petrol cutter, see.

Fuel supply system repair

Fuel may not enter the cylinder for the following reasons:

  • Dirty fuel filter. Remove the fuel hose and check how the fuel flows. If the jet is weak, the filter may need to be cleaned. It is taken out through the filler hole of the fuel tank and cleaned; in case of severe contamination, it is replaced with a new one. As a preventive measure, it is recommended to replace the fuel filter every three months.
  • Clogged breather (holes in the fuel tank cap). Check also by disconnecting the hose, in case of blockage, clean it with a needle.
  • Lack or insufficient amount of fuel. There may be several reasons for the malfunction. The first reason is the clogged air filter. Air ceases to flow into the carburetor in the required amount, in this regard, due to a too rich fuel mixture, the engine’s operation is disrupted. The contaminated filter is carefully removed, cleaned and rinsed in water, then dried and reinstalled.

Another reason is the improper adjustment of the carburetor. The adjustment is made with three screws.

Timely replacement of the fuel filter ensures full fuel supply

The fuel hose and choke actuator must fit snugly against the fittings

The throttle cable must be in place

During work, you must use the instructions, otherwise you can only make it worse.

And the last reason is a violation of the integrity of the membrane or clogging of the carburetor channels.

To repair the carburetor yourself, you need to get acquainted with all its parts.

All parts must be clean, dry and in good condition.

Assessment of the state of the cylinder-piston group

Often the engine will not start or run at full strength due to low cylinder pressure. It can be caused by piston or cylinder wear, piston ring sinking, bearing wear. You can partially examine the condition of the cylinder-piston group (CPG) by removing the muffler and looking into the opened hole.

A compressor placed in the spark plug hole will help to measure the compression in the engine, according to the measurement results, you can also talk about the state of the CPG. Accurate data is obtained only after the complete disassembly of the mechanism. If the piston is chipped or scratched, it must be replaced. The piston ring must be clean, free of carbon deposits, and be exactly in place.

Piston and crank mechanism wear is considered a serious problem.

According to the results of measuring the compression, one can judge the condition of the parts of the CPG

Repairing the chain lubrication system

Consider three main faults:

  • Oil leakage. Check that the pipes are tightly connected to the pump unions and if they are cracked. Problem tubes are sealed or replaced.
  • Insufficient oil supply. Most likely the lubrication passages are clogged.
  • Cracks in the oil pump housing. Part replacement required.

Here’s how to diagnose the lubrication system:

Dismantling and cleaning the muffler

If the engine works fine at low speeds, and at high speeds it starts to stall, the reason may lie in the muffler spark arrester, clogged with combustion products.

  • Remove the muffler;
  • Disassemble (there are also non-separable models);
  • Clean from carbon deposits using detergents;
  • Dry with a hairdryer;
  • Refit.

Dry cleaning is unacceptable, as the soot contains carcinogens, the inhalation of which is dangerous to health. After removing the muffler, close the outlet with a clean cloth.

Interruptions in the operation of the chainsaw signal a possible clogging of the muffler

To prevent the muffler from clogging, it is necessary to monitor the composition of the fuel mixture. The amount of oil should not exceed the rates recommended by the manufacturer. Poor oil quality also negatively affects engine performance.

Checking the ignition system

The first thing to do if the chainsaw breaks down is to inspect the spark plug by disconnecting the wire and carefully unscrewing it with a special key.

Chainsaw ignition system components: 1 flywheel with magnets, 2 ignition module, 3 spark plug, 4 high voltage wire

Unscrew the spark plug to check its condition.

Her appearance says a lot:

  • Dry. Most likely, the fuel mixture does not enter the cylinder. It’s not about the ignition system, so the plug is screwed back in.
  • Strongly splashed with fuel. The reason for the excess fuel mixture lies either in the violation of the starting rules, or in the incorrect adjustment of the carburetor. The spark plug is carefully wiped, shut off the fuel supply and turn on the starter to remove excess fuel and ventilate the combustion chamber. Then the candle is put in place and the mechanism is started again.
  • Covered with black carbon. This may indicate the use of low-quality oil, an incorrectly adjusted carburetor, or an incorrectly calculated gasoline to oil ratio. The candle should be washed, cleaned of carbon deposits with a sharp object (awl or needle), wipe the electrodes with a sandpaper and put in place.

When checking the candle, you need to pay attention to the gap between the electrodes: it is considered normal from 0.5 to 0.65 mm. A damaged or worn gasket must be replaced.

A large amount of black carbon on the spark plug indicates a malfunction of the engine.

To be sure, you should also check for a spark. To do this, put the ignition cable on the spark plug, connect the plug nut and the cylinder with pliers, start the starter and watch for the spark. If it is missing, the plug must be replaced. If the new spark plug also does not produce a spark, the problem is in the high-voltage wire or in a broken connection with the spark plug.

Do-it-yourself chainsaw repair: analysis of major breakdowns and methods of their elimination

It would seem, why does a chainsaw need a summer resident who grows vegetables and fruits, or a country house owner who has a small garden and several flower beds? The question disappears when there is a desire to build a bathhouse, update a greenhouse, knock down an old business, or just make a bench for relaxation. Unfortunately, any mechanism periodically needs preventive maintenance and replacement of spare parts, and for this you need to be well versed in the device of the product, besides, repairing the chainsaw with your own hands will save time and money.