Grass trimmer warms up and shuts down

Causes of power loss in a brushcutter. Lawnmower does not develop the full power

Anyone who owns a dacha or a plot of land, is well aware of the problems of combating excess vegetation. Now came to the aid of a grass trimmer, which has successfully replaced an ordinary mower in this field. This unit is very convenient in operation, but it, as well as any mechanism, because of hard working conditions or incorrect operation is peculiar to mower failure. Situations when the grass trimmer does not gain momentum are quite common. To understand this problem, it is necessary to understand some aspects related to the functioning of the device.

All grass trimmers are classified according to the type of power: gasoline or electricity (from the network or battery). It should be noted that gasoline mowers are superior to their electric and battery-powered counterparts by many parameters. Despite the fact that they all perform similar functions, the difference in performance, maneuverability and efficiency is very noticeable. However, the general principle of operation of all types of manual mowers is almost the same. the devices are equipped with engines (two- or four-stroke engines or electric motors), which drive the cutting unit (spool with a fishing line or a metal disc). All elements are mounted on a straight or curved boom, including a handle to control the trimmer, which houses the main buttons.

Since the problem of weak revolutions is more typical for gasoline versions of trimmers, they will receive more attention. So, the lawnmower is very comfortable to work with and unpretentious in service. At the same time, most of its faults are caused by the user’s ignorance of the elementary things that are written about in the manual. Therefore, before proceeding to operate the machine, it is necessary to carefully study the manufacturer’s manual. In particular, to start the engine, it is necessary to do the following sequential steps:

  • turn on the ignition button;
  • press several times on the silicone button to pump the gasoline;
  • Close the choke;
  • set the throttle lever to the high rpm position;
  • at first, to make some slight jerks with the starter handle to feel the engine resistance, then yank sharply.

If the lawnmower starts but stops, you need to put the choke in the middle position and try again. When the engine starts, you need to turn off the gas and open the air damper, as the grass trimmer works only on the suction.

Important! Grass trimmer operation mode depends on various environmental influences. In hot weather the unit should be given more time to cool down. When working in dense or overgrown vegetation, the engine also overheats strongly. The lawn trimmer needs a five minute break every 15 to 20 minutes.

Reasons for sluggish grass trimmer rpm

If users complain about the grass trimmer, which does not pick up speed, it means that at idle it works fine, but when you press the gas does not develop the necessary power. This can occur as a result of long idle time without activity. These problems are typical for gasoline vehicles, including Husqvarna 128r, STIHL FS 38 and Hitachi different modifications.

Working with the trimmer, it is necessary to monitor its behavior all the time. the drop in rpm and unusual noises signal about the problems in the unit. Sometimes you give throttle, but grass trimmer floats. In such cases, work must immediately be suspended, allow the mechanism to cool down and proceed with the search for possible malfunctions. They can be of a different nature, both technological plan, and external factors related to the conditions and characteristics of the operation of the machine.

External factors

Several factors, not related to mower breakage, influence the decrease of the lawnmower’s RPM:

  • contamination of the filter due to dirt and dust particles getting into it;
  • the use of low-quality fuel;
  • improperly prepared mixture (relevant for trimmers with two-stroke gasoline motors);
  • contamination of the silencer screen with particles of vegetation, soil and other materials.

In the second and third cases, fouling of the combustion chamber and clogging of the carburettor components.

Technical malfunctions

Technical problems of the lawnmower mainly have a place in the fuel supply and ignition system. These can be repaired with your own hands.

  • When the hand-held mower won’t start or stops, the problem may be related to the spark plug. Dark soot indicates poor carburetor adjustment and low quality gasoline.
  • The cause of incorrect operation of the grass trimmer may be a clogged fuel hose. The filters are also often clogged.
  • Another internal problem. muffler is covered with soot. This causes the grass trimmer’s revolutions to drop drastically. The way out is to clean the muffler.
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Important! If the machine doesn’t run because of an engine failure, there could be serious problems. In this case, the malfunctions that can be eliminated with your own hands include only the destruction of piston rings. If there are more serious problems with the motor, if there is no warranty, you should be prepared to visit a workshop.

What could be broken

Troubles with the chain saw, related to the fact that this device does not start, are classified in a certain way by service specialists. They stand out faults with the following assemblies of the mechanism:

  • engine, in which a piston and bearings may be worn or fail, or the crankcase may be cracked;
  • fuel supply system, with possible filter clogging or carburetor problems;
  • mechanical damage of wires, tubes, hoses;
  • The ignition circuit.

To correctly identify the node where the failure occurred, it is necessary to pay attention to the circumstances under which the trimmer for grass stalls.

Ways to fix the breakdown

On the carburetor, subsequent work is likely:

  • Cleaning and adjusting the fuel valve;
  • similar work with the valve releasing the processed gases and vapors (after burning fuel);
  • replacement of the spring with a weaker one on the inlet valve;
  • restoration of carburetor cable tension;
  • Replacing the fuel suction hose, checking and reinforcing the loose connection;
  • replacement of rotary disc shutter;.
  • Changing the faulty wire or ignition coil.

Immediately after starting

Stuttering brushcutter or trimmer for grass right after the start is justified by the following reasons:

  • Balancing of previously adjusted valves may be out of balance;
  • Valve set incorrectly in the beginning;
  • The fuel valve is clogged with sediment;
  • The hose is worn or loose.

Lawn mower or weed trimmer vibrates strongly during operation because of a faulty fuel injection method.

grass, trimmer, shuts, down

Chain problems with chainsaw chain

In addition to engine problems, a chainsaw can have problems in operation due to a malfunction in the cutting (sawing) assembly, which consists of the oil pump, bar, and saw chain.

There is no oil on the bar

Usually, if there is no oil in the chain of a chainsaw, you need to check the channels that carry oil to the bar, and clean them from contamination. If the previous steps didn’t find the cause, you’ll have to check the oil pump. This requires:

grass, trimmer, shuts, down
  • remove part of the chainsaw cover;
  • remove the clutch;
  • unscrew the 3 screws and remove the cover hiding the pump;
  • get to the worm gear that turns the pump shaft.

If the threads on it are worn, the shaft does not turn, the pump does not work, the chain is not lubricated. A worn pinion needs to be replaced. You can also pull out the oil pump itself and manually try to pump oil through it. If it is not pumping, the pump should be replaced.

Don’t forget to take the oil filter out of the reservoir and clean it if needed.

Also lack of lubrication can be due to leakage. Check the tightness of the pipes coming from the oil pump. If the tightness is broken, the tubes are replaced with new ones.

The chain is broken

If the chain broke while the chain saw was running, it could be because it hit a hard object like a nail. If the chain keeps breaking, it could be due to.

  • Metal of the saw chain is of poor quality. You have to buy chainsaws from well-known brands.
  • Chain overheating due to bad lubrication. As a result, the saw overheats, the properties of the metal change, and the chain breaks under load. The chainsaw’s entire lubrication system needs to be checked (discussed above).

information about the causes of chain breaks can also be found in this video.

grass, trimmer, shuts, down

The chain does not rotate

This defect often occurs to inexperienced chain saw owners. They forget to remove the brake after starting the engine. As a result, the chain won’t turn, the brake system overheats, and the clutch mechanism fails. The problem is solved by unbraking the saw. If the clutch is not “burned out,” you will notice the chain spinning. Otherwise the clutch needs to be replaced.

The chain dulls quickly

Most of the time, the reason the chain dulls quickly is because the saw is of poor quality. Trying to save money on the purchase of brand-name chains, chain saw owners buy saws from unknown manufacturers, or inexperiencedly buy imitations of well-known brands. It is best to buy the sprocket from a brand-name retailer. STIHL saw chains are very popular with the owners of these machines.

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The chain will not stop

If you notice while working with a chainsaw that the chain does not stop when you need it, this problem can occur in two different ways.

  • Brake band gets dirty. Dirt, debris, dust, etc., can get under the chain while the saw is working.д. The brake is blocked and the chain will not stop when you release the throttle. The problem can be solved by cleaning the chain.
  • The brake band is worn out. This element of the braking system must be replaced.

The chain is jammed

It happens when the drive or idler sprocket wears out. Chain usually starts to jam under load. But the saw can still rotate without any load. The photo below shows a worn chainsaw drive sprocket.

In the following photo you can see that the cause of the chain blockage is in the location of the chain sprocket.

But what to do if the chain saw is completely jammed and all attempts to pull the starter motor are ineffective?? This defect is sometimes found on Chinese-made chainsaws. It is caused by the bolts that screw the engine to the plastic cover of the machine, unscrewed by vibration. These screws are located right under the flywheel. The arrows in the photo below show the location of the problematic bolts.

As they unscrew, they start to rub against the flywheel and can totally jam the chain saw. The following photo shows the flywheel with existing bolt scuffs.

To fix the problem you will need to remove the flywheel from the engine shaft and tighten the bolts.

Chainsaw is cutting awkwardly

This problem can occur if the chain is blunt or not properly sharpened. This mostly applies to new chain saws. But if the bar is worn out, even after replacing the chain, you will notice that the saw swings to the side. The wear on the bar can easily be determined by placing it on a flat table and placing an angle against it, as shown in the following photo.

In this case, you can see that there is a gap of about 2 mm between the bar and the angle. This unilateral wear on the guide bar is why the chain saw cuts awkwardly. The problem can only be solved by changing the guide bar for a new one.

Important: To keep the chainsaw bar long, it needs to be removed and turned over from time to time. This ensures that the tire wears more evenly and does not cause the chain to skew.

Correct selection of the guide bar

Overheating of the lime can cause the coil to burn out, resulting in the need to replace it. Battery voltage to consider when selecting. If the coils are not properly selected, the part will burn out at high battery voltage and low resistance.

The coil resistance value is classified as follows:

  • High resistance (resistance more than 2.6 ohms);
  • In the average resistance (resistance 1.9-2.6 ohms);
  • Low resistance (resistance 1.4-1.8 ohm).

The most popular are vaps with a resistance of 1.8 ohms and a voltage of 3.7 V.

What might be broken

Problems with the chain saw, related to the fact that this device does not start, are classified in a specific way by service technicians. These include malfunctions with the following parts of the machine:

  • The engine, in which the piston and bearings can wear out or fail, crack the crankcase;
  • fuel supply system, with all this there may be a clogged filter or problems with the carburetor;
  • mechanical damages of wires, tubes, hoses;
  • ignition circuit.

To correctly find the node where the failure occurred, you need to pay attention to the circumstances under which the trimmer for grass stalls.

Main causes

There may be the following reasons why your lawnmower or grass trimmer stops when you try to restart and continue the interrupted operation:

  • engine problems
  • failure in the gasoline and oil supply system;
  • damage of pipelines (capillaries, hoses, connections);
  • Faults in the ignition system.

A general description of problems with a mower or trimmer is not enough here. Clear and immediate repair, high quality service is not possible without specifying the identified cause.

The main causes

There may be the following reasons why your lawn mower or grass trimmer shuts down when you try to restart and continue the interrupted operation:

  • malfunctions in the engine;
  • Failure in the gasoline and oil supply system;
  • damage to the pipelines (capillaries, hoses, nozzles)
  • Faults in the ignition system.

A general description of a problem with a mower or trimmer is not enough here. A clear and immediate repair and a high-quality service is not possible without specifying the cause.

When the throttle is depressed

If the lawnmower stops when you press the gas, the following could be the reasons.

  • A more common variant. it’s a failure of carburetor adjustment, which appears when there are significant loads on the drive after long periods of inactivity of the mechanism or when using it in harsh conditions.

If the problem is related to the carburetor unit, you can recognize it by the appearance of vibration of the lawnmower. When the hose is burst or the cable is stretched, these components must be replaced.

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At high revs

When the grasshopper stalls at high speeds, it is due to the following problems

  • a clogged or jammed valve located on the gas tank lid;
  • carburetor is distorted by the vibrations produced by the machine;
  • Fuel mixture circulation problems;
  • Atmospheric air leakage;
  • the hose that is intended for fuel intake is cracked or loose.
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The carburetor is adjusted, based on the operating instructions to the trimmer. It is often sufficient to loosen the tightening of its housing for adjustment. If there are problems with the circulation of the fuel mixture, it may flow into the carburetor little by little. After it has run out, the engine shuts down at high RPMs.

Malfunctions that lead to improper chain saw operation

There are a number of faults that need to be taken into account when diagnosing, i.e. к. they can lead to malfunctions in the saw.

  • Worn crankshaft bearings. If the crankshaft bearings are worn, runout is inevitable on the main shaft, where the flywheel is mounted. In such a situation, it is impossible to adjust the gap between the flywheel and the ignition coil, which leads to interruptions in spark formation, and unstable operation of the chainsaw.
  • Contamination of the impulse line. Impulse channel is used for fuel pump operation, respectively, its contamination leads to incorrect pump operation, which will make it impossible to operate the saw (it will start and immediately shut down).
  • Wear and tear on the cylinder head. As a rule, when there is increased wear on the cylinder, there is a decrease in compression in the chainsaw engine, which is bound to affect its ability to develop rpm.
  • Contamination of fuel and air filters.

When you press the gas

If the brush stops when the throttle is depressed, the causes may be.

  • The most common variant failure to regulate the carbs, which occurs when the drive is heavily loaded, after prolonged idling of the mechanism or when it is used in difficult conditions.
  • Clogging of the fuel valve, which fixes it by relaxation, as a result of which gasoline begins to flow normally through the system.
  • Weakening and lowering of the cable in the carburetor. They can also happen a fuel hose extension before it bursts, caused by a significant load.
  • Clogged breather tube (check valve), as a result of which fuel does not get into the tank.

If the problem is related to the assembly of the carburetor, it can be recognized by the appearance of vibration of the brush cutter. When the hose bursts or the cable is stretched, these components are replaced.

At high speed

When the braid lingers at high speed, it is due to the following problems:

  • A clogged or jammed valve located on the gas tank lid;
  • The carburetor is not aligned with the vibrations that occur during operation of the mechanism;
  • Fuel mixture circulation problems;
  • Air flow rate;
  • The fuel injection hose is cracked or loose.

Carburetor settings, Based on the instruction manual for the grass trimmer. To adjust, it is often enough to loosen the tightening of the body. If there are problems with the circulation of the fuel mixture, it can gradually get into the carburetor. After it develops, the engine stops at high speed.

When it heats up

Motocosis often stops when it heats up. At the same time, it starts, works “jerkily” and gradually stops. This process occurs when the gas in the carburetor is boiling or the shutter in the carburetor is set to a rotary rather than a disc type. In the latter case, the element changes.

It happens that the grass trimmer heats up if the ignition wire or coil is damaged. For the correct operation of the device it is necessary to replace the parts.

When the throttle is open

It happens that the unit opens when the air damper opens, idling normally. This is due to air leaks in the system caused by the presence of a cracked fuel hose or an oil problem. The carburetor metering system may also fail to operate, while the brush device will stop after the flap opens.

All possible causes of the queen cell stopping and ways to fix them are outlined in the following video.

There are many reasons to stop a brushcutter, but the most common problems are problems related to its carburetor They can occur in any case. The most problematic variant. When a major breakdown occurs and you need to buy new parts or change your brush cutter.