The lawnmower stalls at full speed. Lawn mower stops

Why a lawn mower stops: the most frequent causes, their diagnosis and elimination

Gasoline grass trimmer is a useful tool for clearing large areas of lawns and lawns from unwanted grass. The design of this equipment is quite complex, so if the device breaks down, there can be several reasons. The most likely factors that caused the failure are usually described in the user manual. Knowing why the grass trimmer stalls, you can try to fix the defect yourself. The most common malfunctions that provoke a stop of the brushcutter, and the possibility of repairing them with your own hands. in the material below.

Gasoline grass trimmer is a useful tool for clearing unwanted grass from lawns and lawns of large areas. The design of this equipment is quite complex, so if the device breaks down, there can be several reasons. The most likely factors that caused the breakdown, are usually described in the user manual. Knowing why the grass trimmer stops, you can try to fix the defect on your own. The most widespread malfunctions that provoke a stop of a brushcutter and the possibility of repairing them with your own hands. in the material below.

If stalled under load

Sometimes the grass trimmer stops under load because it can’t pick up speed. This means that the cable in the carburetor is loose and slack. If you are experienced in repairing the machine, the cable should be retightened.

Another cause of malfunction is that the fuel intake hose is stretched too much. When loaded, it stretches even more, resulting in cracks, and eventually the part deteriorates. To fix the problem, you will need to replace this element.

Adjusting and tuning the carburettor

Maximal and minimal engine rpm, even idle speed are regulated with a carburetor. The stable operation of the lawnmower depends on the quantity of mixture and air fed and their proportions. Lawn mower will not start if carburetor is out of adjustment. The adjustment procedure for low speed (L), high speed (H) and idle speed (T) is regulated with the same-name screws:

  • The chainsaw should run for at least 10 minutes, because the adjustment is done on hot.
  • Turn the screw H slowly until the maximum revolution speed and then turn it ¼ of a turn anticlockwise to reduce the engine revolution speed.
  • Regulate the idle speed with the screw T, so that the grasshopper does not rotate.
  • Screw L is adjusted by first opening the throttle as much as possible and then gradually reducing the rpm to a steady minimum.

After adjustment, a working carburetor with cleaned filters, checked ignition should allow the engine to run. If the carburetor is faulty, after repairing it, you will need to adjust the feed system again before starting the lawnmower.

Rare breakdowns that prevent the lawnmower from working can be:

Well if even after such mockery your grass trimmer won’t start, you can’t do without disassembling the carburetor. A needle sticking in it may be to blame. At idle stalls. When it heats up her grass trimmer immediately glows why glows. Why does the hot one stall? ? What kind of grass trimmer to buy when it’s hot?? Hitachi. In any case, disassembly and washing this capricious mechanism certainly does not hurt.

In general, when the grass trimmer is naughty and sits up, it is advisable to perform a complete preventive maintenance: completely change the fuel mixture, try another oil, and also change the spark plug. Practice shows that in many cases it is cheap poor-quality plugs that are to blame.

We have considered the most typical reasons why the grass trimmer won’t start. If the problem is more “exotic”, you will need to go to the service center. You will surely find smaller and more obvious breakdowns on your own.


All the prerequisites, why the mower does not start, can be systematized by the specifics of the individual components. In the service center malfunctions are systematized:

  • engine malfunction (piston wear, bearing failure, cracked crankcase);
  • malfunction of fuel consistency supply. clogged pores of the air filter or carburetor failure;
  • ignition system does not work;
  • Mechanical malfunction. leaking hoses, broken wires under the braid, broken tubes.
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The user should first check if there is any fuel in the tank. Start according to the manual with the saw on its side. Close the choke, pump the fuel, turn the ignition on and give 3 to 4 jerks of the starter. STIHL 250 chain saw stalls on gas, throttles on full throttle. If engine starts, open choke. STIHL 250 chain saw stalls on throttle, what’s the reason? The lawnmower won’t start. repeat the operation with a slightly open air damper.

If it fails to start, start looking for the reason for the failure:

  • check the quality of fuel;
  • Check that the spark plugs are working properly and that the spark plug passage is clean;
  • check the cleanliness of the air filter;
  • Check that the fuel filter is not blocked;
  • check breather plug cleanliness;
  • clean the exhaust duct.

complex reasons will be, detected in the diagnosis of malfunctions, leading to an overhaul of the carburetor. Such causes include clogging of the internal channels of the carburetor, wear on it the gasket and violation of the tightness of the internal hollows with loss of vacuum. Lawn mower repair with their own hands, if it does not start, will require patience.

Block: 2/7 | Characteristics: 1671

Grass trimmer maintenance using Husqvarna 333R as an example, to prevent grass trimmer repair

Т.О. Grass trimmer (lawnmower) is done to:

  • in hot weather and with any load the grass trimmer engine does not overheat;
  • Provide accurate adjustment of the carburetor and, accordingly, the optimal work of the brushcutter engine;
  • Identify possible defects, fuel leaks, and other malfunctions to avoid grass trimmer repairs;
  • timely change spark plugs, unreliable bolts, gaskets, and other consumables;
  • So that the grass trimmer (lawn mower) has a good look;
  • so you don’t have to take your grass trimmer to the service center.

Т.О. of the Husqvarna grass trimmer after rolling out every 40 to 60 liters. gasoline

(depending on the heat, dustiness and severity of the work).

Servicing the grass trimmer air filter

Air filter wash after rolling out the engine every 20 liters of gasoline, and before doing grass trimmer repair or grass trimmer maintenance.

To service the air filter: remove the foam element of the air filter and wash it with soap and water, squeeze and dry it (or replace it if the foam element is old or damaged).

Note: The air filter can be “washed” more often to prevent a drop in power, increased fuel consumption, difficulty starting, and wasted wear on the lawnmower’s engine.

Note: If you adjust the grass trimmer carburetor with a dirty air filter, then after cleaning the air filter, more air will flow into the engine and the fuel mixture will become much poorer, which will lead to poor operation or even to engine failure and as a consequence. the grass trimmer repair.

Preparation for maintenance and repair of grass trimmer

  • to provide (buy and dilute) a usual for the work of your grass trimmer fuel mixture (for example, gasoline A-95 “Mustang” from gas station WOG and two-stroke oil Husqvarna, in a proportion of 1:50) and leave 1,5 l of pure (without oil) gasoline for washing the engine parts;
  • buy a new spark plug: only Champion RCJ6Y. according to Husqvarna manufacturer’s instructions;
  • prepare water-washing supplies for the T.О. and grass trimmer repair (~7);
  • prepare gasoline-washing accessories (~5);
  • buy the right Husqvarna bolts and screws to repair your brushcutter (new fasteners);
  • prepare thin paronite for the gasket under the carburetor of grass trimmer, fishing line for trimmer “round” 2,7-3 mm, gear lubricant, clamps, fuel filter;
  • Provide good lighting, a clean room and a working place for the grass trimmer repair (a tray for laying out parts and spare parts, a stand for the motor, padding for keys and tools);
  • Ensure personal ability to work (if necessary);
  • Allocate one free day specifically for maintenance and repair of the grass trimmer (lawnmower).

Starting maintenance and repair of the grass trimmer

  • Lubricate grass trimmer gearbox. Remove the metal blade or trimmer head and clean the brush chuck inside from grease and dirt.
  • To wash with warm water and a brush all on handlebar, all on boom and both guards (lawnmower guards, as a rule, strongly “overgrow” a dried up mixture from soil and juice of grass, therefore plastic guards it is desirable to brush off with a brush on metal, and then with the washing powder and a brush. Rinse and dry everything.
  • Inspect everything on the trimmer for cracks, bends, scuffs, misalignment, and tears (especially the metal blades at the base of the teeth and at the holes and both guards). Do all faults detected on your brushcutter and have them corrected. Remember! the thickness of the metal is calculated on the computer, so the tightening of fasteners should be carried out only in the service center on a special fastener tightening card with a torque wrench. If tightening the fasteners do it yourself, do not overtighten!, because if it heats up too much (e.g.- If you have to tighten the fasteners (screws, nut caps, gearboxes) in hot weather under heavy load, metal expands, and there is little thickness reserve and the body can burst (give a crack).
  • Install the trimmer head (T-35) with a cord 2.7 mm or 3 mm in standard length (up to the cutting blade in the additional protection) to load the engine to adjust the needle high rpm, that is the left screw of the grass trimmer carburetor.
  • Rinse and drain fuel from the tank into a bottle.
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Disassembly of Husqvarna 333R grass trimmer (order of disassembly of engine for t.о. and grass trimmer repair

Remove the muffler cover. one bolt.

Turn the grass trimmer over on the table and remove the metal tray (three screws).

Remove the starter block (this is the air intake of the grass trimmer engine cooling system). three screws and two rubber bands!

Unfasten the air filter cover and remove the cylinder cap (it directs the cold air to the cylinder). one bolt.

Unscrew the three bolts in the air filter housing (one short and two long).

Carefully disconnect the throttle cable from the carburetor.

To inspect while everything is dirty. the carburetor on the trimmer and its gaskets, hoses, the tank, the plug on fuel leakage (cracking and leaks).

Remove the fuel tank with two hoses (disconnected with a screwdriver very carefully) and four supporting rubbers (do not lose).

Remove the Zama C1Q carburettor together with the air filter housing and the gasket.

Remove the choke button with a screwdriver (you must make a mark there for subsequent installation).

By turning the carburetor on the trimmer, remove it from the air damper rod on the body and then from the other rod.

lawnmower, stalls, full, speed

In a new Champion RCJ6Y spark plug (for Husqvarna), set the gap to 0.5 mm. Unscrew the old spark plug and install a new spark plug in the grass trimmer cylinder! (The old candle is either thrown away immediately, or cleaned, set the gap and prepared to be washed to hide it in the stockpile).

Why the Chinese lawnmower does not revolve ?

Chinese lawn mower analog Husqvarna does not develop speed the reason was very simple (see video)

Vibrations that occur during operation of the lawnmower can lead to misalignment.

Incorrect adjustment of the lawnmower, however, can be corrected by simply adjusting it according to the requirements specified in the instruction manual.

In addition, sometimes gasoline grass trimmers can stall because the valve located in the gas tank lid, just clogged or jammed.

To find out, try using a scythe by loosening the gas tank cap.

If the device works properly in this mode, clean the valve.

Before sorting out why any of the tools of a dacha-gardener or a professional working with a brushcutter (gasoline mower) stalls. it is worth distinguishing between two main situations when it happens. The first is when the tool does not start after you have just made the purchase, and the second is when it has been in operation. So, let’s break down both.

  • After start. The lawnmower stops if the carburetor is not set correctly, or if there was a disconnection of the carburetor. The fuel is not delivered evenly and, consequently, there is a distinct vibration.
  • After heating up. The situation when the mechanism starts and works, but gradually “crushes” and stops in motion. when the carburetor boils gasoline, or the flap in the carburetor is not a disk, and rotary. In such cases, it is better to replace the carburetor itself. There is a variant of air suction. when the coil or wire in the ignition is punctured.
  • At high rpm. This also occurs from an unbalanced carburetor or a clogged cap on the gas tank. It is worth trying operation with a slightly opened valve. Be sure to check the fuel intake hose. it may be cracked or poorly attached to the base.
  • Not picking up speed. As the main reason why the engine does not pick up revs. the air filter is clogged. The cable in the carburetor may have fallen off, the carburetor may be broken and there may be problems with the mechanics of the engine.

There are times when a part of the mechanism needs to be replaced, so we are always happy to offer. It is important to realize that sometimes saving money on minor items can result in failure of a major component such as the carburetor or engine. Intelligent operation and timely replacement of the right parts ensures that you will be able to work at full pleasure.

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At high rpm

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

  • clogged or jammed valve located on the gas tank lid;
  • The carburetor is unadjusted due to the vibrations that occur during the operation of the mechanism;
  • Problems with fuel mixture circulation;
  • atmospheric air intake;
  • the fuel hose is cracked or loose.

Adjust the carburettor according to the instruction manual of the trimmer. To adjust the carburetor, it is often sufficient to loosen the tightening of its housing. If there are problems with the circulation of the fuel mixture, then it may slowly flow into the carburetor. the engine stops at high revs after it has worked out.

What to do if the engine does not start?

The engine oil is filled with gasoline using a metal syringe so you know exactly what proportion of the components you need

A dirty fuel filter in the tank can also prevent the lawnmower engine from working. So if you have trouble starting the engine, check the condition of the filter. Replace the filter if necessary. Never leave the inlet without the fuel filter.

The air filter also needs checking. If dirty, remove the part, wash it in gasoline in the field and put it back. In the cottage or at home, the filter can be washed in water, using detergents. Then the filter is rinsed, wrung out and dried. The dried filter is moistened with a small amount of oil used for the fuel mixture. remove excess oil by squeezing the filter with your hands. Then reassemble the part. Replace the removed air cap and secure it with screws.

The air filter, washed in fuel mixture, squeezed and dried, is installed in place in the plastic housing and closed with a cover

How to do this procedure in more detail you can see at

If all the above procedures are done and the engine will not start, adjust its idle speed by turning the carburetor screw. The video at the beginning of this article focuses on this issue.

  • Place the tool on its side so that the air filter is at the top. This arrangement allows fuel mixture to be delivered exactly to the bottom of the carburetor. The engine will start at the first attempt if you remove the air filter and pour a few drops of mixture into the carburetor before start, then put the removed parts back in place. Method tested in practice.
  • If the first tip fails, the problem is most likely in the spark plug. In this case, unscrew the spark plug and check its function and dry the combustion chamber. Replace a spark plug that is not showing signs of life with a new one.
  • If the spark plug is in good condition, the filters are clean and the fuel mixture is fresh, you can use the universal method of starting the engine. Close the carburettor choke and pull the starter grip once. Then open the choke and pull the starter 2-3 more times. Repeat the procedure three to five times. The engine will definitely start.

Some pull the handle with such force that they have to make lawn mower starter repair with their own hands. This is only possible if the cable is torn or the cable handle is broken. In other cases, replacement of the starter is recommended. This assembly is sold as a complete unit.

Ways to fix a breakage

The following work is possible on the carburetor:

  • cleaning and adjustment of the fuel supply valve;
  • Similar work with the valve, which releases the exhaust gases and vapors (after burning fuel);
  • replacement of the weaker spring 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;.
  • replacement of faulty wire or ignition coil.

The list of work performed may also include nozzle cleaning (in a 4-stroke engine), replacement of valve washers, gaskets in the tank plugs, and so on.

lawnmower, stalls, full, speed

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