Lawn Mower Won’T Start Reasons

How not to get confused if the lawn mower won’t start
The scythe does not start during the harvest. Troubleshooting and remedies. Do-it-yourself repairs and in specialized centers. Instrument operating rules.


lawn mower won't start reasons

All the reasons why the lawn mower does not start can be classified according to the specifics of the operation of individual units. In the service center, faults are classified:

  • Engine malfunction (piston wear, bearing malfunction, crankcase crack);
  • Malfunction of the fuel mixture supply – clogged pores of the air filter or carburetor malfunction;
  • The ignition system does not work;
  • A mechanical malfunction – leaking hoses, broken wires under the braid, ruptured pipes.

The user first needs to check if there is fuel in the tank. Start up in accordance with the instructions, with the saw on its side. Set the air damper to the “closed” position, pump up fuel, turn on the ignition and make 3-4 sharp jerks with the starter. If the engine is running, open the air damper. The lawn mower does not start – repeat the operations with the air damper slightly open.

If the launch fails, we start looking for the reason for the failure:

  • Check fuel quality;
  • Make sure that the candle is working and the candle channel is clean;
  • Check the cleanliness of the air filter;
  • Make sure the fuel filter is not clogged;
  • Check the cleanliness of the breather;
  • Clean the outlet.

complex reasons will be found during the diagnosis of malfunctions leading to overhaul of the carburetor. Such reasons include clogging of the internal channels of the carburetor, wear of the gasket on it and a violation of the tightness of the internal halls with a loss of vacuum. Do-it-yourself lawn mowers repair, if it won’t start, will take patience.

Eliminating the reasons why the lawn mower won’t start

The fuel mixture must be prepared with the exact proportions of gasoline and oil. In this case, you cannot use another brand of fuel. To exclude the ingress of dirt, gasoline must settle in glass or metal containers for 2 days. Do not use plastic utensils for storing fuel. Measure oil accurately with a medical syringe without a needle. Use only freshly prepared mixture, do not leave unused fuel in the tank. If the engine is naughty, the lawn mower stalls, when you press the gas, the fuel may be to blame.

Checking the ignition system, if the lawn mower does not start, is carried out sequentially:

  • Clean the removed candle from carbon and dirt, dry it, set a gap of 1 mm;
  • Connect to a high-voltage wire and check for a spark by pulling the starter several times;
  • In the absence of a spark, check the high-voltage wire for integrity;
  • Replace the candle;
  • Dry the candle channel;
  • At the same time the operation of the ignition coil is checked, it is faulty if the working plug does not spark.

It is in the event of a malfunction of the ignition coil that the lawn mower does not start up hot, stalls, and works intermittently.

Cleaning or replacing the air and fuel filter will ensure the proper consumption of ingredients entering the carburetor. The air filter can be washed in soapy water or replaced. If nylon fabric is used, it is washed, the porous felt filler is replaced. Change the fuel filter carefully without leaving the intake manifold open. Whether it is necessary to replace the air filter can be determined if the engine starts with the air cleaner removed. Whether it is necessary to change the grid on the fuel supply if the lawn mower does not start, a dry candle will tell you.

Breather, gas tank air inlet. If it becomes clogged, a vacuum is created in the tank and the mixture does not enter the carburetor. The hole can be blown out with air or cleaned with a needle. Clean the exhaust duct, remove the anti-spark screen for the muffler.

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How not to get confused if the lawn mower won’t start

The tool, despite its small dimensions, is a complex technical device. If you study the operating instructions, it turns out that the reasons why the lawn mower does not start are known and removable. It is necessary to consistently eliminate factors that make it difficult to start the tool. Usually start with more accessible nodes with an easy health check.

The lawn mower will not start, the spark is gone

The loss of a spark entails checking the contacts and the correctness of the gap between them, the conducting wires to the candle and the candle itself.
The way to check the spark is to unscrew the candle, connect the wire to it, put the candle sideways to the motor casing and pull the starter several times as if starting the lawn mower, while looking at the coal and the contact of the candle, a spark should run between them.
If there is no spark, take a new candle, follow the same procedure, if the spark cannot be traced, then there is a problem in the wire or contacts, it is better to replace them.

The lawn mower won’t start after winter

In such cases, the unit must be serviced. Remove the fuel system, including filters (air, fuel), disassemble the carburetor, clean and rinse each unit. Blow out the filters with air. Pay attention to fuel quality and octane number.

It should be borne in mind that products of such well-known companies as STIHL, Husgvarna and other brands will not run on cheap gasoline with a low octane number.
Suitable fuel for them is from the AI ​​brand – 92 and higher from car gas stations and then from well-recommended ones, since there is also bad gasoline at gas stations. The use of high-octane and high-quality gasoline will determine how long the lawn mower will be used and how long it will last.

It is necessary to take into account one more fact that with a long storage of a diluted fuel mixture, its working qualities fall, which also leads to consequences in which the lawn mower does not start. Therefore, it should be diluted in portions, that is, the amount of the mixture that is produced at a time.
The operating instructions clearly describe and explain the mixing ratio of gasoline and oil. Strict adherence to the correct proportions will at least save you from several questions about why the lawn mower won’t start and what to do in such cases.

The lawn mower will not start on a cold

When starting a cold engine, it is not recommended to press the gas. Tilting the mower so that the air filter is on top, press the fuel suction button 5-6 times, set the function switch lever to the “start” position, pull the starter cord several times until the engine starts. After a few seconds of running the motor, turn off the starting system.

When heated

The lawn mower often stops when it heats up. At the same time, it starts up, works "jerky" and gradually stops. This process occurs when the gasoline in the carburetor boils or the damper is installed in a rotary rather than disc type. In the latter case, the part is changed.

It happens that the trimmer heats up if the ignition circuit wire or coil is damaged. In order for the device to start working normally, parts are replaced.

At high revs

When the scythe stalls at high speeds, this is due to the following problems:

  • Clogging or sticking of the valve located on the gas tank cap;
  • The carburetor is out of alignment under the influence of vibrations arising during the operation of the mechanism;
  • Problems with the circulation of the fuel mixture;
  • Suction of atmospheric air;
  • The fuel intake hose is cracked or loose.

Adjust the carburetor according to the trimmer operating instructions. For adjustment, it is often sufficient to loosen the tightening of its housing. If there are problematic points with the circulation of the fuel mixture, then it can gradually enter the carburetor. After its development, the engine stalls at high speeds.

What could have broken

Problems with the lawn mower due to the fact that this device does not start are classified in a certain way by service specialists. They highlight faults with the following components of the mechanism:

  • An engine in which the piston and bearings may wear out or fail, crack the crankcase;
  • The fuel supply system, while the filter may be clogged or problems with the carburetor;
  • Mechanical damage to wires, tubes, hoses;
  • Ignition circuit.
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Lawn mowers filter diagnostics

Another reason why the gasoline scythe stalls is the air filter. To eliminate it, try removing the filter and starting the trimmer without it. If possible, then you will have to change the air filter to a new one, or at least blow through and thoroughly clean the old one.

The petrol trimmer may not start if the fuel filter is dirty. This is the next step in our algorithm. Here we check the condition of the filter element and, if necessary, replace it with a new one. When replacing, try not to leave the suction pipe completely without a filter, this is prohibited by any operating instructions. Haste can turn into repairing the engine piston group.

complex reasons for lawn mowers failure

If the step-by-step troubleshooting algorithm does not work, and your scythe still does not start or stalls, it is worth inspecting the carburetor and the engine itself. A clogged carburetor can be one of the reasons for erratic tool performance. There are three main problems here:

  • Clogged ducts or nozzles. All this is cleaned by special washes or blown by a powerful jet of compressed air from the compressor. Do not use needles and wires, as the bore may be damaged;
  • Worn carburetor gasket. Exit – replacement of a failed gasket;
  • Violation of tightness. To check this indicator, you can use an ordinary household tonometer, replacing it with a suitable pressure gauge. Watch the readings: if they do not change, everything is fine, and if the pressure starts to drop, then some part of the carburetor is faulty. We’ll have to find it and replace it with a new one.

If everything is in order with the carburetor, then the petrol trimmer may not start due to wear of the piston group. If chips, scratches or scuffs are found, the piston or cylinder should be replaced. Piston rings are subject to mandatory checks. A small backlash of the piston when rocking the connecting rod indicates that it is time to change the rings. It is best to entrust this procedure to the specialists of the service center.

We carry out diagnostics of a candle and a candle channel

If the quality of the fuel mixture is not in doubt, and the lawn mower stalls when started, then a flooded candle may be the cause. Here, for repairs, an ordinary spark plug wrench (probably every motorist has) and a spare candle are suitable.

  • We unscrew the candle and wipe it;
  • Dry it thoroughly (do not ignite);
  • We drain the excess fuel in the chamber through the spark plug hole and dry it;
  • We clean the old candle from carbon deposits using a file or a lady’s file;
  • We expose a gap with a distance of 1 mm (you can check with any coin);
  • We put everything back in place and try to start the trimmer.

If the candle is working, the socket where it is located is completely dry, and the lawn mower does not want to start, lubricate the threaded connection with gasoline. It should be slightly damp. No matter how wonderful a spark the candle may give out, there is simply nothing to ignite in a dry chamber.

If the trimmer motor still does not start, you should exclude such a reason as the absence of a spark due to poor contact between the spark plugs and the high-voltage wire. If the connection is of good quality, but there is still no spark, most likely, your ignition unit has "flown". Here it will not be possible to do without a master, since the part is not repaired, but sold as a single unit.

Do-it-yourself breakdown elimination

Success in self-repair of a tiller largely depends on how correctly you diagnose the unit. The reasons why the tiller won’t start may be hidden in the following:

  • Clogged air does not pass through the air filter;
  • The hole in the fuel tank cap is clogged;
  • Debris has accumulated in the fuel supply channels;
  • Broken carburetor.

Each of these faults can be easily and quickly eliminated by hand. If this is not the cause of the breakdown, and the unit still does not start, then you should unscrew the spark plug and check for oil stains. If you find oil or thick carbon deposits on the candle, then the part must be cleaned and dried. In addition, drying will also be required for the tiller cylinder – for this, you need to sharply pull out the starter rope several times.

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It is often difficult to start a tiller due to the lack of fuel in the combustion chamber. In this case, the candle will be completely dry. If the cause of the breakdown is this, then the following measures will need to be taken:

  1. Drain the old fuel completely;
  2. Flush the fuel tank thoroughly;
  3. Clean the air filter from clogging;
  4. Blow out the fuel supply hose with compressed air;
  5. Blow out the carburetor jets;
  6. Pour fresh gasoline into the tank;
  7. Open the fuel cock;
  8. Purge airway inside fuel tank cap.

Before restarting, you will need to manually pump up fuel by pressing the primer of the fuel pump several times. After starting the engine, be sure to give it time to warm up, after which you can start working with the tiller.

If all the above steps did not help, and the tiller still does not start, then check the inlet and outlet valves – if they do not fit tightly to the seats, then the parts will need to be adjusted by turning the corresponding screws clockwise.

Also, if the tiller does not start, we advise you to pay attention to its muffler – after long-term operation, carbon deposits accumulate on its walls, which must be regularly removed with compressed air.

Why not start a tiller?

Despite all the reliability of modern tillers, sooner or later they fail, which is why the unit cannot be started and continued to work on the site. We propose to study the most common breakdowns of agricultural machines, as well as do-it-yourself methods for eliminating them.

Why not start a tiller – we understand the reasons

Before the start of the season, both the gasoline and diesel tiller need preparation. To do this, the owner of the unit must make sure that the design of the unit contains all the parts necessary for operation, and each of them “sits” tightly in its proper place.

Often, many Tillers equipped with a Subaru engine or other well-known brands refuse to work after a long winter standstill. At the same time, the incorrectly chosen storage conditions of the agricultural machine also affect – if it stood in a cold damp room, then, most likely, it will not start before the start of spring work. This is due to a number of such malfunctions:

  • Oxidation of contacts in electrical wiring;
  • Violation of the integrity of the insulation of the wiring;
  • Watering of oil and fuel;
  • Debris build up in carburetor jets.

Before starting the tiller, its owner must carefully inspect all the connections in the unit design. It is necessary to check the course of the throttle, reverse and clutch cables – it should be soft. If during inspection you find clamps or twists in the cables, then you cannot start the tiller.

Before starting the chiller for the first time, check the oil level inside the crankcase. If there is no lubricant, this will lead to severe damage to the piston group. Judge for yourself: at a crankshaft speed of 1400 rpm, it will take a fraction of a second for it to form a few burrs on the cylinder surface.

The oil remaining for the winter is one of the main reasons for the unstable operation of the unit motor. It is quite simple to make sure that the tiller does not start well for this very reason – after starting for a few seconds, white smoke will fall from the exhaust pipe of the car, after which the unit will stall. Do not forget that both diesel and gasoline tiller will not start well due to insufficient oil. Some models of units are equipped with a low level protection; owners of other machines should independently monitor the volume of oil inside the tank.

Another important factor is the gasoline you use to fill the tiller. If you regularly fill with fuel of the wrong brand, which is recommended by the manufacturer of the car, then this can also cause it to not start.