Lawn Mower Won’T Start For Hot Reasons

Lawnmower won’t start: causes and remedies

Diagnostics of the reasons why the lawn mower won’t start. Quick return to life of Chinese and domestic two-stroke internal combustion lawn mower.

It happens that a two-stroke motor does NOT show even a flash in the cylinder, but it happens. Grabs, and then stalls. Do NOT be sad, this Chinese consumer goods can be repaired right on the knee with a minimum of tools.

Before starting diagnostics, you need to make sure that the motor rotates with little resistance. If there is compression in it, it means that further is useless, and you need to change the piston (there is nothing complicated about this either, everything is like a designer).

Everything whole, clean, works?

Trying to adjust. We take a long screwdriver, find the idle speed adjustment bolt (it is located on the throttle valve), twist it a couple of turns so that the damper opens slightly. We start. Does it work smoothly? Then let’s move on. Won’t start or stall? Opens the damper until it starts steadily.

Then we adjust the quality of the mixture by screw L. It is necessary to achieve maximum idle speed. Here the principle is reversed. The more the bolt is loosened, the richer the mixture. After that, the quality of the mixture is adjusted at maximum speed with the screw H.

If the carburetor adjustment does not work, then it needs to be disassembled. Watch the membrane, cleans the jets and internal passages. To do this, it is necessary not only to have a repair kit, but, preferably, a spare carburetor.

First. Candle

The first step is to unscrew the candle. If it is wet, the ignition system is faulty. Try to wipe the spark plug, put it in the cap, attach it to the engine, pull with the starter. Spark. There is? If not, then you need to change the candle.

Replacing the spark plug didn’t help? Then you need to watch the magneto, cable, ignition coil. The cable is ringed, the coil is checked for resistance (the multimeter is in resistance measurement mode at 200 Ohm, one contact for ground, the other. To the output of the coil, it should show from 0.4 to 2 Ohm).
Sometimes the magnets on the flywheel get dirty, or the key is licked off, and the ignition moment flies away. Chinese shit throws up all kinds of surprises, but for the most part, everything can be revealed visually.

Necessarily need Pay attention to the plaque of the candle. If it is black, the candle is smoked, then the mixture is rich, or you have mixed the fuel incorrectly. If the plaque is white, it means that the mixture is poor, and the engine could already die of temperature. Ideally, the color should be brick, light, without much plaque.

Again, if the black candle is dead, do not immediately sin on the carburetor and ignition. Screw in a new one, see what the plaque will be. Maybe the candle was just of poor quality.

Second. Carburetor

It is not necessary to disassemble the unit right away, especially if the engine stalls after starting or does not keep idling. Try changing the fuel first, it may have an excess of oil. You can inject the purifier into the air filter, give the motor a little “fuck up” at maximum speed.

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Next, we go in order. Air filter, fuel filter (it can be outside and in the tank), fuel pump button, hose integrity. Gas tank cap. The ventilation valve may be clogged, the motor simply does not pump gasoline. Purge everything. And it will work!

Required. Look at the connection of the carburetor to the intake manifold! Elsi sucks air there and there is no tightness. Eliminate!

Dispensing needle hangs up. Also a problem in some models. It is enough to push it down, or remove and grind it with velvet.

You can pull off the hose from the carburetor, see if the fuel goes to it when pumping. It is clear that often for checking you need to remove the plastic sheathing, break your fingers into the latches, but anyway, sooner or later you will have to climb there.

What is the resource in Chinese lawn mowers?

A Chinese or Russian lawn mower is capable of working about 500 hours. But this is with the right mixture, good oil, good factory assembly. If a person pours gasoline from one good gas station, accurately measures the same oil in beakers, regulates the carburetor for the same mixture, the fuel burns correctly, then the longed-for half a thousand hours of motor life. Quite affordable bar.

But here we must not forget about the Chinese marriage. They even balance the shafts on the knee, install the cheapest bearings. Carburetors are stamped with clogged channels. If a person understands the principle of operation of a two-stroke engine and a carburetor, understands how to sort it out, then he can finally assemble an almost perfect trimmer.

In general, if we consider a Chinese lawn mower as a space for creativity, then even its breakdown. A reason to learn something new, this is a construction set for a man.

If you need a tool, then you should look for a Japanese analogue, or switch to an electric model.

Starter malfunctions. Do not turn the starter

Most often, the starter does not turn on hot due to the fact that when heated, the bushings expand slightly in size, due to which the starter shaft wedges or does not turn at all. Also, the reasons that the starter does not start on hot are the deterioration of electrical contacts in the heat, contamination of its internal cavity, violation of the contact group, contamination Pyatakov.

To troubleshoot, you need to get rid of the listed reasons. However, there is a couple folk methods by which even a worn starter can be made to rotate with significant heating.

Breakdown cause
what to do
bushing wearreplace
deterioration of contactsClean, tighten, lubricate contacts
Reducing the insulation resistance of the stator / rotor windingCheck insulation resistance. Eliminated by replacing the winding
Contact plates in solenoid relaysClean or replace “Pyatak”
Dirt and dust in the starter housingClean interior, rotor / stator / contacts / cover
wear of brushesClean the brushes or replace the brush assembly

There can be 5 reasons why the starter does not turn hot, and almost all of them are characteristic of cars with high mileage.

  • Reduced bushing clearance. If bushings or bearings with a slightly increased diameter were installed during the next repair of the starter, then when heated, the gaps between the moving parts decrease, which can lead to wedging of the starter shaft. A similar situation is observed when regular bushings wear out. In this case, the rotor skews and begins to touch the permanent magnets.
  • Deterioration of contacts in the heat. A bad (loose) contact heats up by itself, and if this happens at an elevated temperature, then insufficient current flows through it, or the contact can completely burn out. Often there are problems with the guidance from the ignition switch to the starter (oxides) or poor mass from the battery to the starter. There may also be problems in the contact group of the ignition switch.
  • Decrease in winding resistance. With an increase in temperature, the value of the resistance of the stator or rotor winding on the starter can significantly sink, especially the unit is already old. This can lead to a decrease in the electromotive force, and, accordingly, the starter will turn badly or not turn at all.
  • Pyatak on the retractor relays. Relevant for VAZ cars classic. In them, in the retractor relays, over time, the so-called penny. Closing contacts. They burn on their own, with use, however, at high temperatures, the contact quality deteriorates even more.
  • Dirty rotor. Over time, the starter armature becomes dirty from brushes and from natural causes. Accordingly, his electrical contact worsens, including he may become attached.
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Taking proper care of your chainsaw

There are unnecessary phrases in the operating instructions, everything that is offered is aimed at trouble-free operation of lawn mowers. Cleaning of all parts after each work cycle helps to easily remove non-hardened residues and dirt. You need to clean only the cooled nodes. This technique contributes to the quality of air cooling of the engine and gearbox.

When storing the equipment for the winter, conduct an audit, lubricate the gearbox and piston system, Wrap all dust in oiled rags and store in a dry place.

It is impossible, it is dangerous for the tool and the health of the mower, to use a metal cable instead of a fishing line. It cuts more efficiently, but the load on the gearbox and engine increases. A worn-out piece of wire during separation flies at the speed of a bullet.

Why is it bad on hot? If the engine does not start well on Why the trimmer does not start. Effective mowing can lead to early wear of the engine piston group.

For more efficient mowing it is suggested to use the line profile star.

Breather and exhaust port

Often, gentle branded lawn mowers DO NOT start and stall due to a dirty breather. The main function of this element. Equalizing the pressure in the gas tank. When this unit becomes clogged, a vacuum is created in the tank, preventing the supply of fuel. Eliminate the problem by cleaning the breather. You can use a regular needle for cleaning.

Normal operation of streamers with internal combustion engines may be impaired due to dirt entering the exhaust duct or clogging of the muffler mesh. There is such a problem on older generation models. The issue can be resolved by traditional cleaning and removal of the anti-spark grid.

To the content

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:

Lawn Mower Won'T Start For Hot Reasons
  • 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 or wires as the bore may be damaged;
  • Worn carburetor gasket. Output. Replacing a failed gasket
  • Violation of tightness. To check this indicator, you can use an ordinary household tonometer, Replacing a suitable pressure gauge on it. Watch the readings: if they do not change. Everything is fine, but if the pressure starts to drop, then some carburetor part is faulty. We’ll have to find it and replace it with a new one.
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If everything is in order with the carburetor, then the gasoline trimmer may NOT start due to wear of the piston group. If chips, scratches or scuffs are found on the piston or cylinder, they should be replaced.

Piston rings are subject to mandatory checks. A small LUF of the piston when wiggling the connecting rod indicates that it is time to change the rings.

This procedure is best entrusted to the specialists of the service center.

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;
  • Gearbox breakage;
  • The starter has broken;
  • Air filter problems;
  • Gas tank breather clogged.

Electric trimmer vibrates

Many mower users have noticed that some time after the start of the machine, it begins to vibrate strongly.

Some trimmers, mostly in more expensive models, have an anti-vibration system in the form of shock absorbers located between the engine and the boom. But in some cases, even it does NOT save from strong vibration.

The reason that strong vibration appears in the trimmers may be a small amount or a complete lack of lubrication on a rigid or flexible shaft located inside the apparatus bar.

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 generously lubricated with special grease. “CV joint-4” either the usual. “Litol-24”;
  • Apply a small amount of grease to the shaft and smear it evenly along the entire length of the part, including the splines at the ends of the rod (if they come off, the shaft will have to be replaced)
  • After lubrication, insert the shaft back into the rod and replace 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 entire length of the cable with grease.

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 evenly distribute it over the surface. Then insert the flexible shaft rod into the electric motor and secure it.

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


As you can see, there are a number of reasons why the gasoline trimmer may not start.

However, with a serious approach to the task, the malfunctions indicated in the material can be easily eliminated by hand. It is worth seeking help from specialists only in case of critical breakdowns.

Ultimately, the cost of self-repair should always be correlated with the cost of servicing the unit in the workshop.