Trimmer Does Not Accelerate At Full Throttle

Trimmer Does Not Accelerate At Full Throttle

  1. Causes
  2. Troubleshooting Methods
  3. Little tricks

It is not necessary to purchase an expensive and bulky lawn mower to cut grass on a small lawn; it can easily be replaced with a gasoline / electric trimmer. The device of these machines is quite simple, they are convenient 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 (of course, subject to proper care). Most often, malfunctions arise due to contamination of structural elements.

If the engine of your lawn mowing does not start, does not gain momentum, does not reach the power you need, or suddenly stalls, the cause may be:

  • Low-quality fuel (fuel mixture), it may be in long-term storage or in non-compliance with the formulation of the mixture;
  • Grass wound on the shaft of the fishing line / knife head;
  • Clogged air filter / muffler;
  • Imbalance carburetor.

Troubleshooting Methods

The first three reasons are pretty easy to eliminate. If the matter is in the mixture, it is necessary to pour the old fuel from the tank, prepare a new emulsion from high-quality gasoline and engine oil (if your engine needs a mixture) and pour it into the fuel tank. If the trimmer runs on clean gas, it’s still easier.

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

The last reason why the lawn mow is not working properly will require a little more knowledge and skills from you.

To correctly adjust the carburetor lawn mowers, you must follow a certain procedure. First clean the air filter thoroughly. It is easiest to rinse it (it is advisable to flush the filter with water regularly after 9-10 hours of operation).

After that, in the scheme of your trimmer, which is in the instruction manual of the device, find the adjustment screws. Usually there are three of them: the first is responsible for supplying fuel, the second for idling, well, and the third is designed to limit the number of maximum engine speeds.

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

Slowly tighten the first adjusting screw (fuel mixture supply). Catch the moment when the motor starts to stall, and turn the screw in the opposite direction by 45 degrees. If you do not have time and the motor stalls, you should turn the screw 90 degrees. Open the throttle and see how the speed increases. Next, you should slowly unscrew the screw (each turn is the same 45 degrees) until the moment when at full throttle the motor begins to firmly produce a maximum of revolutions.

The second screw, as mentioned above, controls the engine idle speed. By weakening it, you reduce the number of revolutions, twisting – increase. The screw must be adjusted so as to ensure reliable motor operation at low speeds. For a better start, speed up the engine a little. At the same time, make sure that the motor makes several dozen revolutions before the movement of knives / reel with fishing line. If the engine starts poorly, tighten the screw a little.

After you have adjusted the first two screws, test the operation of the device 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. Loosen the lock nut until the adjusting screw can be easily turned. To increase the maximum number of revolutions, the screw must be loosened, to reduce – on the contrary, tighten. Lock the position of the screw with a nut. Test the motor again.

Remember that carb adjustment is not the final procedure. During the operation of the lawn mowers, you most likely will have to bother with it more than once, because an unbalanced carburetor means both increased fuel consumption and quick failure of 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 normally, it may be because the spring is too thick and stiff. Then you can choose a more suitable one instead.
  • If your unit does not need pure gasoline, but a mixture of it with engine oil, strictly observe the proportions indicated in the operating instructions. There is one trifle: the recommended ratio is 1: 25 (for all brands of oil) or 1: 50 (for “native” oils). Try the first ratio first. If with this recipe oil leaks appear on the motor, and a strong deposit forms on the candle, halve the proportion of oil. Usually this contributes to the disappearance of traces and reduce the amount of soot.
  • To clean the electrodes of the candle from combustion products, you can use a fine-grained "sandpaper". Wipe them with a dry cloth first and then gently scrub them with sandpaper. If the space between the device’s body and the insulator is also clogged, a plain, unclipped paper clip will help clean it. To do this, soak the candle for a short time in diesel fuel, and then scrape off the dirt. If the blockage is small, one procedure is enough. With severe contamination, sometimes you have to repeat it several times. After thorough cleaning, the candle must be wiped dry from the remains of diesel fuel, and then it can be used for its intended purpose.
  • Please note that a lawn mowing machine (gasoline, electric or battery) of foreign production requires a little more care than domestic ones. In particular, many people insistently recommend entrusting professionals with adjusting the carburetor of a two-stroke engine, especially if your warranty has not expired.
  • And finally, one more tip: follow all the manufacturer’s recommendations on the operation and maintenance of the device. So you extend its trouble-free operation.

What to do if the gas trimmer is not gaining momentum, you will learn further.

Any person who owns a cottage or land is well aware of the problems of combating excess vegetation. Now a trimmer has come to the rescue, which has successfully replaced the usual braid in this field. This unit is very convenient to use, but it, like any mechanism, tends to fail due to difficult working conditions or incorrect operation. Situations are quite common when the trimmer does not gain momentum. To understand this problem, you need to understand some aspects related to the operation of the device.

Video: Trimmer Does Not Accelerate At Full Throttle

Features of the trimmer

All trimmers are classified by type of power: gasoline or electricity (from the mains or battery). It should be noted that gas mowers in many respects surpass their electric and battery counterparts. 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 hand-held mowers is almost the same – the devices are equipped with engines (two- or four-stroke ICEs or electric motors) that drive the cutting unit (reel with fishing line or metal disk). All elements are fixed on a straight or curved rod, including a handle for controlling the trimmer, on which the main buttons are located.

Since the problem of low revs is more characteristic of the gasoline versions of trimmers, more attention will be paid to them. So, the lawn mowing is very comfortable in operation and unpretentious in maintenance. Moreover, most of its malfunctions are caused by the user’s ignorance of the elementary things that are described in the instructions. Therefore, before starting operation of the unit, it is necessary to carefully study the manufacturer’s manual. In particular, in order to start the engine, it is necessary to do the following sequential actions:

  • Turn on the ignition button;
  • Press the silicone button several times to pump gasoline;
  • Close the air damper;
  • Set the throttle lever to high revs;
  • First make slight jerks with the starter handle to feel the resistance of the engine, then sharply yank.

If the lawn mowing is started, but stalled, you need to put the air damper in the middle position and try again. When the engine is working, you need to slow down the gas and open the air damper, since the trimmer only works on the suction.

Causes of weak trimmer revs

If users complain about a trimmer that is not gaining momentum, this means that at idle it works fine, and when you press the gas it does not develop the necessary power. This can happen as a result. Long downtime of the device without activity. These problems are typical for gasoline vehicles, including Husqvarna 128r, Stihl FS 38 and Hitachi of various modifications.

When working with the trimmer, you need to monitor its behavior all the time – a drop in speed and unusual noise signal a malfunction in the unit. Sometimes you give gas, and the trimmer floats. In such cases, work immediately needs to be suspended, allowed to cool down and proceed with the search for possible problems. They can be of a different nature, both the technological plan, and external factors associated with the conditions and features of the operation of the device.

External factors

Several factors that are not related to its breakdown have an effect on reducing the speed of lawn mowing:

  • The filter is dirty due to the ingress of particles of dirt and dust;
  • Use of low-quality fuel;
  • Improperly prepared mixture (relevant for trimmers with two-stroke gasoline engines);
  • Pollution of the silencer mesh by vegetation particles, soil elements and other objects.

Moreover, in the second and third cases, carbon deposits in the combustion chamber, and elements of the carburetor become clogged.

Technical issues

Technical problems of lawn mowers mainly occur in the fuel supply and ignition systems. You can deal with them yourself.

  1. When the hand mower does not start or stalls, the problem may be with the candle. Dark soot indicates poor carb adjustment and low gasoline quality.
  2. A clogged fuel hose may cause a trimmer to malfunction. Filters are also often clogged.
  3. Another internal problem – the muffler is covered with soot. This greatly reduces the speed of the trimmer. Exit – you need to clean the muffler.

Diagnostics and troubleshooting of petrol engines

Before proceeding with the repair of a particular unit (part), it is necessary to determine the nature of the malfunction. Step-by-step diagnostics and troubleshooting – further.


This mechanism is an important component of the gas trimmer. In order for the carburetor to work properly, several conditions must be observed:

  • Disassemble and clean it at times;
  • Adjust the idle speed according to the instructions;
  • Refer to the wizard for help with adjustment.

In the event of a breakdown of this unit, it is possible to repair it yourself, but only if you have certain knowledge.

One of the reasons for carb carb malfunctioning is relaxed cable. To fix the problem, you first need to disassemble the entire assembly, and then, thoroughly rinsing all the parts, grease and tighten the cable, but not very much so as not to stretch.


In case of problems with a candle, sometimes it is enough to dry it or sand it with sandpaper and put it back in place, setting the gap correctly – it should be 1 mm. If the candle is very covered with soot, it is better to replace it with a new one. With the optimal operating mode of the trimmer, the candles do not so often fail.


Clogging air filter ─ Another reason for the unreliable operation of the device. To check the involvement of this element in the malfunction, you need to start a lawn mowing without it. A dirty filter can be washed in gasoline, dried or replaced with a new one.

Clogged fuel filter does not pass fuel into the cylinder, and the engine stalls at full throttle due to an elementary lack of gasoline. This element is located inside the tank on the intake hose. To fix the problem, instead of the old filter, put on a new hose or rinse thoroughly the one that was removed.


The engine is the most important part of any unit. The causes of engine failure are several:

  1. Incorrect proportions of oil with fuel (for push-pull);
  2. Old fuel mixture;
  3. Wear and destruction of the piston ring;
  4. Traces of scratches on the cylinder and piston;
  5. Operation of the device for wear.

All this leads to the fact that the engine either does not start or stalls.

Fuel system

For the trouble-free operation of the gas trimmer, the functioning of the fuel system is of great importance. Gasoline passes through all its components and parts, so they should be cleaned regularly. In addition, only high-quality fuel must be used. For the preparation of a combustible mixture in a two-stroke engine, motor automotive oil cannot be used, since it has insufficient qualities.

Diagnosis and troubleshooting of electric motors

Trimmer failures can be as follows:

  • Insulation failure or cable breakage;
  • Malfunctions in the area of ​​the cutting tool;
  • Damage to the socket or plug.

To deal with these breakdowns, you do not need to disassemble the entire device.

With serious engine trouble will have to disassemble it. To do this, unscrew a few screws. Having access to the details of the motor, you need to carry out such actions:

  • Check the degree of wear of the brushes – unsuitable parts will need to be replaced with new ones;
  • Ring the motor winding – the resistance should be high;
  • Check the stator and rotor – to test the rotor winding with a multimeter, measure the resistance: large deviations from the norm indicate a malfunction, the absence of resistance on the stator winding also indicates a breakdown (the stator case is diagnosed in the same way).

Problems with low revs are common for cheap trimmers. However, with improper maintenance, manual mowers such as Huter, Patriot 3055, and Echo also suffer from this.

When to contact the workshop

If the device is under warranty, at the first sign of malfunctioning, it can be safely taken to a specialized workshop. Repair will be done free of charge, regardless of the nature of the damage, if it happened through no fault of the owner. In the event of engine breakdowns, it is better for a person who is not knowledgeable in technology to contact a specialist immediately. In any case, the severity of problems with the unit is determined by the user.

Summarize. Both gasoline and electric trimmers are designed for many years of reliable operation. Most of the problems described above are due to the lack of attention of the owner to his assistant. Subject to strict adherence to requirements from the manufacturer and regular maintenance, the hand mower will operate rhythmically and without interruption.

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