the lawn mower is not picking up speed reason

The gasoline trimmer is not gaining momentum: the reasons and features of the repair

lawn, mower, picking, speed

It is not necessary to purchase an expensive and bulky lawn mower to cut grass on a small lawn; it can be easily replaced by a gasoline / electric trimmer. The device of these machines is quite simple, they are easy to use and unpretentious in maintenance. But sometimes problems do occur. One of them – when the trimmer does not develop the maximum number of revolutions – will be discussed in this article..


Trimmers are reliable and durable (provided they are properly maintained, of course). Most often, malfunctions occur due to contamination of structural elements..

If the motor of your lawn mower does not start, does not pick up speed, does not reach the power you need, or suddenly stalls, the reason may be:

  • low-quality fuel (fuel mixture), the case may be in long-term storage or in non-compliance with the recipe for preparing the mixture;
  • grass is wrapped around the shaft of the fishing line / knife;
  • clogged air filter / muffler;
  • unbalanced carburetor.

Troubleshooting methods

The first three reasons are fairly easy to eliminate. If the matter is in the mixture, you need to pour out the old fuel from the tank, prepare a new emulsion from high-quality gasoline and engine oil (if your engine requires a mixture) and pour it into the fuel tank. If the trimmer is running on clean gasoline, it’s even easier.

In the second case, it is necessary to carefully free the trimmer parts from the wound grass..

If the filter is clogged, you can try rinsing it. If this procedure does not bring any effect, replace it with a new one..

The last reason a lawn mower doesn’t work properly will require a little more knowledge and skill from you..

To properly adjust the carburettor for lawn mowers, a specific procedure must be followed. First, clean the air filter thoroughly. The easiest way is to rinse it (it is advisable to douse the filter with water regularly after 9-10 hours of operation).

After that, in the diagram of your trimmer, which is in the instruction manual of the device, find the adjustment screws. There are usually three of them: the first is responsible for fuel supply, the second is for idling, and the third is designed to limit the number of maximum engine speed.

Next, turn on the unit and wait for the engine to warm up.

Tighten the first (fuel mixture) adjusting screw slowly. Catch the moment when the motor starts to stall and turn the propeller back 45 degrees. If you did not have time and the motor stalled, the screw should be turned 90 degrees. Open the throttle and watch the revs increase. Next, slowly unscrew the screw (each turn is the same 45 degrees) until the moment when, at full throttle, the engine begins to firmly give out maximum revolutions.

The second screw, as mentioned above, controls the engine idle speed. By loosening it, you decrease the number of revolutions, while twisting it, you increase it. The screw needs to be adjusted so that the motor runs reliably at low revs. For better starting, speed up the engine slightly. At the same time, make sure that the motor rotates several tens of times before starting the movement of the knives / line reel. If the engine starts poorly, tighten the screw a little.

After you have adjusted the first two screws, test the operation of the unit at maximum engine speed. If necessary, you can limit it (maximum) – this will protect the motor from “boiling”. To do this, you need to tackle the third screw. Unscrew the locking nut until the adjusting screw can be safely turned. To increase the maximum number of revolutions, the screw must be loosened, to decrease – on the contrary, tighten. Fix the position of the screw with a nut. Test the motor again.

Check the position of the screws regularly – the high vibration levels of lawn mowers can cause them to move unintentionally.

Remember that carburetor adjustment is not a final procedure. During the operation of lawn mowers, you will most likely have to tinker with it more than once, because an unbalanced carburetor means both increased fuel consumption and a quick failure of the candles, not to mention a decrease in the power and performance of the device..

Little tricks

  • If you are unable to tighten / loosen the adjusting screws properly, it may be that the spring is too thick and stiff. Then you can choose instead of her a more suitable.
  • If your unit does not need pure gasoline, but its mixture with engine oil, strictly observe the proportions specified in the operating instructions. There is one little thing: the recommended ratio is 1: 25 (for all brands of oil) or 1: 50 (for “native” oils). Try the first ratio first. If, with such a recipe, oil drips appear on the motor, and a strong carbon deposit forms on the candle, reduce the proportion of oil by half. This usually helps to fade traces and reduce the amount of carbon deposits..
  • To clean the spark plug electrodes from combustion products, you can use fine-grained “sandpaper”. Wipe them down with a dry cloth first and then gently sand them with sandpaper. If the space between the body of the device and the insulator is also clogged, a regular unbent paper clip can help clean it. To do this, briefly soak the candle in diesel fuel, and then scrape off the dirt. If the blockage is small, one procedure is sufficient. In case of heavy dirt, it is sometimes necessary to repeat it several times. After complete cleaning, the candle must be wiped dry from the remaining diesel fuel, and then it can be used as directed..
  • Please note that foreign-made lawn mowers (gasoline, electric or battery) require a little more maintenance than domestic ones. In particular, many strongly recommend entrusting the adjustment of the carburetor of a two-stroke engine to professionals, especially if your purchase has not expired the warranty period..
  • And finally, one more tip: follow all the manufacturer’s recommendations for the operation and maintenance of the device. This will prolong its smooth operation..

You will learn more about what to do if the petrol trimmer is not picking up speed..

Regarding the carburetor, the source of malfunction can be:

  • wear of piston components;
  • littering it;
  • breakdown of the air filter;
  • the use of gasoline with a low octane number and inadequate quality;
  • damage due to vibration effects of the tool itself.

Each individual model is usually based on a 3-screw adjustment method, and the “H” screw will help to reach the maximum torque..

And yet, if the chainsaw does not develop speed, perhaps even the reason is not in itself, but in the time of year in which the work is being carried out. So, the minus mark of the thermometer is one of the factors that can completely “knock down” the chainsaw. Many users note that in severe frosts, even pouring hot oil does not help and the grease involuntarily solidifies on the tire. Ice coating of the carburetor and frost on it is also a fairly common thing. What can be done?

Reduce the operation of the tool before the onset of the body, or, if the design allows, change the damper mode from summer to winter, which is installed on individual models under the air filter cover.

The following actions can help:

  • throttle cable check;
  • inspection of the return spring, which could simply come off;
  • sealing the rear flap, which must be very tightly closed.

Usually, one of these activities can make a lot of sense..

Another technical problem is the situation when the chainsaw itself is gaining momentum, the reason for which is usually more than one. In this case, as well as under load, the saw may start to stall from time to time, preventing it from being fully used for its intended purpose.

What to do if the chainsaw does not slow down?

The opposite of the previous situation is when the gasoline tool very quickly reaches high power and does not slow it down. In this case, it can be observed that neither the screw on the body, nor the cleaning of the carburetor can eliminate this in any way. It would seem, what else is needed, the saw works, gives out power as in the instructions. But the trouble is that in this case, you need ten times more fuel than usual..

All about the speed of gasoline saws

Modernization does not stand still. And the old chain chainsaws, which, besides being able to only saw wood, emitting a terrible roar and vibration, heard almost for kilometers, are long in the past. Almost silent, sophisticated tools that are now a pleasure to hold in their hands have flooded the market, giving users a feeling of complete happiness and technical freedom..

But, to our great regret, no matter how detailed technically and visually advanced technology is, its breakdowns are a fairly frequent occurrence, which manufacturers speak about only “by default”. Chainsaws are no exception to this, multifunctional working units that require tremendous attention to themselves from the user in order to recognize the “catch” in time and stop the problem at the earliest stages..

The main of these nuances usually relate to the moment of launch, which should be taken with full responsibility. Let’s look at the main processes that can occur with a chainsaw when the engine is turned on..

The chainsaw is not gaining momentum – what to do?

Moreover, this phenomenon may be accompanied by the fact that the motor periodically does not start at all, it loses speed, and the load cannot withstand more than idle speed. If you do not pay attention to this problem in time, you can generally “lose” it due to severe overheating..

Read more:  What gasoline to pour into the mower

The main reason for this usually lies in the area of ​​the engine, which is why it is worth taking a closer look there..

What can be the reason that the chainsaw does not idle?

As they say, to start up – it started up, and then it stalls and does not have time to move to the next power level. Many conditions can serve this:

  • clogging of filtration parts;
  • irregularities in the operation of the incendiary system;
  • out of adjustment of the carburetor;
  • the gasoline drive is defective or damaged during operation;
  • muffler or exhaust ducts clogged;
  • malfunction of cylinder-piston and installed valves.

Of course, it is difficult to independently diagnose everything at once, but moving through the proposed points you can still get an answer to your question. In half the cases, it is enough to clean the carburetor, check the installation of the jets – and the job is done, the chainsaw works as before.

Other points that could lead to such consequences are:

  • malfunctions with spark plugs;
  • problems with the carburetor or simply incorrect adjustment.

The spark plug lends itself to visual diagnostics, therefore, if it is too dry or, on the contrary, very wet, and even with a significant coating on top, it is necessary, if not to replace it with a new one, then simply clean or dry it and try it outside the saw ignition system.

The device does not drive well

The most common causes of such a malfunction are:

  • incorrect adjustment of the wheel drive cable;
  • clogged bushings or wheel bearings;
  • Leaking lower oil seal of the engine crankshaft;
  • poor quality or too large drive belt.

It is necessary to start the test by adjusting the wheel drive cable, this procedure is described in detail in the manual for the petrol lawn mower.

It is necessary to move the cable adjustment so that the drive engages with less pressure on the lever. If this does not help, it is necessary to return the cable to its original state, then prepare the mower for replacing the belt, all preparatory actions are also described in detail in the operating instructions.

To check the ease of rotation of the wheels, tilt the mower by raising the front and rear parts alternately, and also by hand checking the ease of rotation of the wheels..

How To Fix A Surging Engine on a Lawn Mower, Pressure Washer, Tiller etc – Video

Even the drive wheels connected to the gearbox must, albeit with effort, rotate when they are turned by hand. The other pair of wheels, not connected to the gearbox, should turn much more easily. If the drive wheels cannot be rotated with one hand, it means that the gearbox requires maintenance or replacement, at home this should only be done if you have extensive experience in repairing such equipment.

If the drive wheels do not rotate tightly, then it is necessary to check the condition of the bushings with which they are connected to the mower body, possibly the bushings are clogged with grass. To cope with such a problem, it is necessary to remove the wheels, then pull the shaft out of the bushings and clean all the elements from adhering grass, a detailed description of this operation is in the operating instructions for the lawn mower.

To carry out the following steps, you need at least a minimum of locksmith and repair experience associated with any motorized equipment. If you do not have such experience or you are not sure that you can handle it, it is better to entrust the performance of these work to a specialized workshop or service center..

After draining the oil and gasoline, the gasoline lawnmower is placed on the table, turning the muffler to the bottom or with the wheels towards the top..

Then remove the knife and belt guard (all these operations are described in detail in the operating instructions of the lawn mower) and check the tension of the latter, and also look for traces of oil.

If the belt is very stretched, then it must be replaced with a new one, this can be done independently, however, certain locksmith skills will be required.

If there are traces of oil, then it is advisable to deliver the device to a service center, because special equipment and certain skills are needed to repair it..

Engine won’t rev or keep revving

The most common reasons why the engine is not picking up speed are:

  • incorrect position of the choke lever or breakdown of its drive;
  • dirty air filter;
  • faulty manual accelerator control system.

At home, without special equipment and skills, you can only check:

Lawn mower wont pick up the grass properly. Simple fix

  • condition of the air filter;
  • operation of the air damper drive lever (only on those models where the air damper position is manually adjusted);
  • a manual accelerator control system, that is, a special lever on the folding handle and a cable connecting it to the carburetor.

Checking the condition of the air filter and flushing it is described in detail in the mower‘s operating manual, and we examined the check of the throttle position regulator in the previous section..

To check the manual accelerator control system, you need to set the lever to a position where the engine speed will correspond to that required for mowing, then mark its position with a marker and, after waiting for them to decrease, compare the position of the lever relative to the mark.

If the lever matches the mark, then the problem is much more serious and you need to contact the service, if the lever has moved, then you need to replace it.

Some inexpensive Chinese devices are supplied with a factory defect, including an incompletely assembled air damper actuator or its incorrect adjustment..

If you know how to eliminate such defects, then you can do it yourself, if not, we recommend that you immediately contact the service center so that the mower can be repaired under warranty..

Many modern lawn mowers are equipped with automatic speed control, so they can only be diagnosed in a workshop..

The mower emits a lot

The reason why the mower smokes may be due to the following:

  • gasoline prepared for two-stroke engines was poured into the fuel tank, or it was stored in an oil container;
  • the air damper position regulator is faulty or is in the “Off” position;
  • too high oil level;
  • the mower, filled with oil, was stored vertically.

To check the gasoline, it is drained, then obviously clean fuel is poured, corresponding to the octane number, after which the engine is started and the grass is mowed. If after 5-10 minutes the gasoline lawnmower has not stopped smoking, then the problem is something else..

If the smoke has disappeared, then it is advisable to replace the spark plug, and in the future, more carefully approach the choice of fuel for the lawn mower..

If the air damper drive is in good working order and its lever is in the “On” position, then it is necessary to check the oil level, if it is above the “MAX” mark on the dipstick, then the excess oil has pushed through the oil seals and now the grease enters the engine.

In this case, it is not enough just to pump out the excess oil, because the oil seals are already pressed, which means that the mower will start to actively consume oil, which, burning in the engine, forms dark smoke.

Therefore, it is advisable to contact a specialized workshop, where they can check the condition of the engine (oil entering the cylinder negatively affects many of its parts), and also replace the crushed oil seals.

If the lawn mower was stored with oil filled in and in an upright position, then you need to contact the service to replace the oil seals and revise other parts, as well as read the operating instructions more carefully and observe the rules for storing the machine outlined in it..

Most common problems

The most common faults are:

  • the engine will not start;
  • the motor stalls arbitrarily;
  • the engine does not pick up speed or does not keep it;
  • immediately after the start of mowing, the engine speed drops and it stalls or works intermittently;
  • smokes a lot;
  • goes badly;
  • does not stop even after the operator releases the wheel drive lever;
  • shakes violently;
  • does not cut the grass well.

Shaking violently

Such a malfunction of a gasoline lawn mower occurs in two cases:

  • when the knife is deformed due to hitting an obstacle;
  • with incorrect sharpening of the knife.

In both cases, the reason for the shaking is the lack of balance of the knife, because when the knife is struck, at least a little, but it deforms, and if the sharpening is incorrect, the metal is removed unevenly on both sides.

As a result, a lever is formed, the length or mass of the arms of which is at least slightly, but different. This leads to the fact that the motor shaft will always pull after the heavier or longer arm of the lever, and due to its rotation, such a force will also move in a circle..

In order to determine the cause, it is necessary to prepare and set the petrol lawnmower to the position for changing the blade (these operations are described in detail in the operating instructions). Then the knife is carefully examined in search of damage, if the external examination did not give anything, then it is removed and balanced.

Read more:  How to Fill a Fishing Line into a Mower

Balancing can be performed both independently (this requires a round wooden or metal bar, the diameter of which is a fraction of a mm less than the diameter of the knife hole), and in the workshop.

When self-balancing, the knife is put on the bar and they see which side will go down, for more accurate balancing, you can slightly twist the knife on this makeshift shaft.

Having determined the heavier side, it is gradually grinded with a file by hand or on a grinder, constantly checking the balance, and the metal is removed only from the side of the blade, keeping the original sharpening angle. In the same way, the knife is sharpened at home, first the edge of the blade, then balancing it.

On some models of gasoline lawn mowers, the shaking may be caused by a broken adapter between the engine shaft and the blade, which protects the shaft from damage in a collision..

To diagnose such a malfunction, it is necessary to set the device to the position for replacing the knife, then shake the knife in different directions and try to rotate it.

If it swings or turns even a little, the adapter needs to be changed – after all, it has fulfilled its task, protected the shaft when the knife stops abruptly, due to which it can no longer reliably fix the knife. Its replacement is also described in the instruction manual..

Gasoline lawn mower malfunctions: the most common problems and their elimination

Like any motorized equipment, the lawn mower sometimes breaks down and stops working or does not work properly..

Moreover, there is always a specific reason why the equipment works intermittently, without eliminating its repair will only lead to a senseless waste of finances and time.

Having understood the device of the lawn mower and the reasons for the breakdown of certain mechanisms, in most cases it is possible to eliminate them yourself..

In this article, we’ll cover:

  • the most common malfunctions of gasoline lawn mowers;
  • the reasons for these malfunctions;
  • diagnostic methods;
  • methods of repair and prevention.

Further verification

If the piston moves, then you must first check the fuel supply, for which the spark plug is thoroughly wiped with a dry clean cloth, then screwed into place, and the air damper position regulator is set to the “Off” position, as when starting the engine.

After that, fuel is pumped up (if the engine design provides for this) and several times pull the recoil starter cable or press the electric starter button and hold it for 1–3 minutes.

Then move the choke lever to the “On” position and unscrew the candle, which is carefully examined.

Wet contacts indicate that gasoline is entering the engine and an ignition problem, while dry contacts indicate:

  • on carburetor models about a faulty carburetor;
  • on mowers with fuel injection about a malfunction of the entire fuel system.

In both cases, knowledge and equipment are needed for correct diagnostics and repairs, so those who are not versed in such work, it is better to take the device for repair to a specialized workshop..

If fuel is supplied, then it is necessary to check the external condition of the ignition coil and high-voltage wire. If they have cracks or poor contact, both between the wire and the coil, and at the junction of the wire with the spark plug tip, they must be replaced..

If everything is fine, then you need to check the spark, for which you can use both a known-good candle and a bolt of a suitable diameter, which is inserted instead of a candle into a high-voltage wire.

The operations described below, if performed incorrectly, can damage the ignition coil, so if you are not sure that you can do everything correctly, then it is better not to risk it and entrust this check to professionals.

The candle is threaded against the ribs of the engine cooling jacket, and the bolt is positioned so that it does not come into contact with the mower body or its engine anywhere, and the distance from it to the cooling jacket was 1–2 mm.

After that, disconnect any wire going to the ignition switch, then pull the manual starter lever several times or press the electric button and see if a spark appears.

If there is no spark, then the device will not start for one of the reasons:

  • breakdown or breakage of the ignition coil;
  • the flywheel key is cut off;
  • the ignition magnet fell off the flywheel.

Skills and equipment are required to repair these damages, so those who do not have them are better off trusting professionals. If there is a spark, then the problem is in the spark plug, so after replacing it, the engine will start working..

Why the motor is not picking up speed: from simple to complex

At the very beginning, we will consider simpler and more obvious faults. The set of revolutions while driving is strongly influenced by the feed efficiency, the timeliness of ignition and the usefulness of combustion, as well as the composition of the fuel-air mixture.

A common reason when the engine does not pick up speed (injector, carburetor, diesel, gas car) is problems in the ignition system, as well as in the air and fuel supply systems. Experts point out the following:

  • Heavy contamination of the air filter reduces the ability of air to penetrate the filter element, as a result of which the engine becomes uneven, the unit loses power and does not pick up speed. Also, a common cause of problems with the air supply can be that a foreign object (rags, plastic bag, etc.) may accidentally become in the air filter housing..
  • You should also pay attention to the suction of excess air at the intake as a result of various defects in the intake system. The problem can appear both unexpectedly and gradually progress. Note that the motor usually does not pick up speed in the event of a strong air leak. The fact is that in the composition of the fuel-air mixture, the normal ratio of air to fuel in such a situation deviates significantly from the norm. The mixture turns out to be very “poor” (a lot of air and a minimum of fuel). On such a charge, the engine starts, but does not gain momentum while driving, and also works intermittently..
  • A similar picture can be observed when the required amount of fuel is not supplied to the unit. The culprit may be the fuel filter, which can also become very clogged. Note that there may be no problems with starting the engine, since there is enough fuel for the XX mode. In parallel with this, while driving, the car may jerk, react to pressing the gas pedal with a long delay, when speeding up, dips may occur or the unit may not spin above any mark on the tachometer.
  • A dirty filter mesh of a gasoline pump can lead to similar symptoms. Deposits from the fuel tank tend to accumulate on the specified filter over time. As a result, the fuel pressure in the system becomes insufficient, the pump performance drops, and the motor itself is not able to operate normally in different modes. It often happens when the engine picks up speed and stalls precisely because of a clogged grid.

Now let’s talk about problems that may require certain knowledge, skills and equipment for diagnostics, and also be a reason for a visit to a car service. To begin with, this list of faults usually includes those when the engine does not pick up speed due to the failure of any element of the ECM, ignition system, power supply, etc. In other words, we are no longer talking about “consumables” (candles, wires, filters, pipes), but about details. In parallel with this, it should be considered whether the breakdown occurred unexpectedly or the malfunction progressed gradually..

  • One of the reasons may be knocked down timing phases. Violations of the synchronous operation of the gas distribution mechanism relative to the intake and exhaust strokes lead to the fact that the intake and exhaust valves do not open in time. The malfunction occurs as a result of errors during the replacement of the timing belt, if the specified timing belt has jumped one tooth or more teeth. Also, the cause may be incorrectly adjusted valves (the problem does not manifest itself sharply), various malfunctions in the systems for changing the valve timing, breakdown of the timing chain drive, etc..
  • Unexpected breakdowns include the failure of the ignition module, as well as malfunctions of the ignition coils. In this case, cylinder misfires begin, the engine troit and loses its ability to gain speed normally..
  • In situations with engine speed, the power supply of the injection nozzles should be checked. If there are problems with the wiring, then the control signal is not supplied to the injector or is intermittently received. As a result, the injector does not open in a timely manner, misfires occur in one or more cylinders, the engine does not pick up the required speed and loses power..
  • A fuel pump or fuel injection pump on diesel engines may fail. This malfunction usually does not occur immediately (unless the electrical wiring to the pump is damaged). Much more often, the drop in pump performance occurs gradually. Sooner or later, the pump will start pumping fuel very weakly, the pressure will be enough only for operation in the XX mode. An increase in load and speed will lead to the fact that the engine may stall under load, not spin up, etc..
  • In some cases, severe contamination of the injector itself leads to similar results. Driving on poor quality fuel, as well as ignoring the necessary cleaning procedure for the injectors every 30-40 thousand kilometers traveled may mean that the performance of one or more fuel injectors has dropped significantly.
  • The engine speed can also be affected by the state of the EGR system, the throughput of the catalyst or particulate filter. As for the second case, exhaust gas evacuation worsens through a clogged catalyst, the engine literally “suffocates” and is not able to pick up normal speed.
  • In parallel, it is necessary to check various sensors of the electronic engine management system. Their incorrect operation can affect the composition of the mixture, that is, the amount of fuel and air supplied to the internal combustion engine. These sensors include DPDZ, DMRV and a number of others.
Read more:  Affordable Speed ​​Adjustable Angle Grinder

Why the engine is not picking up speed well

During the operation of a gasoline or diesel engine, the driver may be faced with the fact that when the gas is pressed, the engine does not pick up speed. Note that after installing LPG equipment on a car, such a problem often arises when the engine on gas does not pick up speed, although the car runs normally on gasoline. Malfunctions of various kinds can cover both fairly simple things and indicate the need for serious repair of the internal combustion engine. Next, we will consider why the diesel engine does not pick up speed or the gasoline engine refuses to spin up..

Frequent malfunction: the engine does not pick up speed and what should the driver do

If the engine stopped gaining speed, then the first step is to analyze when and how it manifested itself. In other words, the unit stopped spinning unexpectedly, or the problem with a set of revolutions gradually progressed. You should also pay attention to the presence or absence of other symptoms..

The fact is that the failure of a previously serviceable engine to gain momentum after carrying out any repairs or other manipulations may simply be the result of assembly errors, an unconnected sensor, etc. In such cases, the malfunction can be determined faster and more accurately after an independent inspection or an immediate return of the vehicle to the service, where the car was previously repaired..

What is the bottom line

Considering that there are a lot of reasons for problems with a set of revolutions on a modern car, it is optimal to immediately connect the car to diagnostic equipment (scanner) to search for possible errors. This is especially necessary to do in the case when the engine does not pick up speed and the check on the dashboard is lit.

Such failures are associated with a software failure in the operation of an electronic device. The ECU mistakenly assumes low speed (for example 2-3 thousand rpm) for the so-called “cut-off” speed and stops the fuel supply. In other words, the conditional protection against exceeding the permissible number of maximum engine speed is triggered prematurely..

Finally, I would like to add that timely cleaning of the injector, replacement of spark plugs and ignition wires, filters and filter elements of the fuel pump, cleaning the throttle valve, correct throttle adjustment and a number of other service procedures will allow you to get the maximum power from your internal combustion engine. As for cars with LPG equipment, not only the engine power and its gas revolutions, but also the overall service life of the power unit will depend on the correct installation and adjustment, as well as on the timely replacement of filters and maintenance of other elements of gas equipment..

Breakage of petrol trimmers

Typical breakdowns of a gasoline trimmer, which the owners of this unit most often encounter, are as follows:

  • engine breakdown;
  • carburetor problems;
  • fuel supply problems;
  • muffler malfunction;
  • breakdown of the gearbox;
  • the starter has broken;
  • air filter problems;
  • gas tank breather clogged.


The breather is a non-return valve designed to equalize the pressure in the gas tank. If it is clogged and does not allow air to pass towards the tank, then a vacuum forms inside the fuel container, and the fuel stops flowing into the carburetor. To check if the valve is working, remove the hose that goes from the reservoir to the carburetor. If gasoline does not flow out of the tank, then the breather is clogged..

Trimmer users often ask themselves: Where is the breather? This valve is usually located in the gas cap and looks like the following illustration..

Cleaning the breather is very simple: disassemble the valve and rinse all of its components. On some mowers, this valve may be located directly on the fuel tank. It will not be possible to find it right away, since it is hidden from view under the starter housing. Such a breather is cleaned with a regular needle..

Fuel tank (fuel quality)

Remember that it is always necessary to check the availability and quality of fuel before starting the unit. In this case, you should not be greedy and save, as well as “be smart” about the amount of added oil. Everything must be done according to the manual attached to the device, since if the piston group fails, its replacement will cost about 70% of the total cost of the trimmer. Fill in fuel on the basis that you will completely use it up when performing work. The gasoline remaining in the tank loses its properties after a while and can harm the engine. Therefore, do not prepare the mixture for future use and in large quantities. If the lawn mower does not start well, try draining the “old” fuel from the tank and refueling it with fresh mixture.

Important! Filling the device with fuel, the origin of which is unknown, is fraught with negative consequences. Gasoline must be of high quality, purchased at a gas station, and its brand must be at least AI-95.

Exhaust channel

The reason that the trimmer has significantly lost power, and when trying to increase engine speed, it picks up slowly, is often a clogged exhaust channel through which exhaust gases come out of the combustion chamber..

It is necessary to remove the muffler so that no burns get into the cylinder. Next, clean the exhaust channel from carbon deposits..

This must be done very carefully, avoiding the ingress of carbon deposits into the combustion chamber..

After this procedure, the weak power of the unit and a slow increase in the speed of rotation of the mowing head will no longer upset you..

Why the petrol trimmer won’t start

The reasons why the petrol trimmer stopped starting may be different, so a step-by-step diagnosis of the device is required.

Electric trimmer vibrates

Many mower users have noticed that some time after the start of the machine, it begins to vibrate strongly. On some trimmers, mainly in more expensive models, an anti-vibration system is installed in the form of shock absorbers located between the engine and the boom. But in some cases, even she does not save from strong vibration. The reason that a strong vibration appears in the trimmer may be a small amount or a complete absence of lubrication on a rigid or flexible shaft located inside the apparatus rod..

Rigid shaft lubrication is changed as follows:

  • unscrew the gearbox located at the bottom of the rod;
  • after removing the gearbox, you will see the end of the shaft, which must be pulled to remove the part;
  • after removing the shaft, it must be abundantly lubricated with special grease “Shrus-4” or the usual one – “Litol-24”;
  • apply a small amount of grease to the shaft and spread it evenly along the entire length of the part, including the splines at the ends of the rod (if they work, the shaft will have to be replaced);
  • after lubrication, insert the shaft back into the rod and put the gearbox in its original place.

The flexible shaft is lubricated as follows:

  • unscrew and remove the mowing head;
  • remove the rod from the electric motor by unscrewing a couple of bolts;
  • pull the flexible cable out of the rod;
  • lubricate the cable with grease along the entire length.

This is done like this: first you need to lubricate the end of the cable, and then insert it into the rod, after which, as it moves inside the pipe, you should apply lubricant to the part and distribute it evenly over the surface. Then insert the flexible shaft rod into the electric motor and secure it.

In the case when the lubrication did not help, and vibration continues to appear, you will need to change the flexible shaft.

Causes of breakdowns of gasoline and electric trimmers

The trimmer, both electric and with an internal combustion engine (ICE), is an indispensable tool in summer and autumn for owners of summer cottages and private houses. With its help weeds, small bushes are easily removed and the lawn is trimmed. But, like any technique, trimmers fail at the most inopportune moment. To fix faults with his own hands, the user of this technique first needs to determine the reason for their appearance..