The grass trimmer does not start what to do. Again, the carburetor.

Lawnmower won’t start: causes and solutions

Does not pump gasoline in the cylinder, with a syringe you squirt it starts up and stops”. with such words a large number of benzocos comes to our service center in the summer period.

Can it be fixed?? Unfortunately not always We will try to tell you about the frequent failures of this carburetor and how to fix them with your own hands.

Before you make any manipulations with the carburetor you must exclude possible malfunctions that can affect the operation of the lawnmower (create a simulation of not working or not tuned carburetor:

Fuel filter (hoses): no mechanical damage on the filter body, no dirt, good flow capacity

  • Air filter: no mechanical damage on the surface of the filter, no dirt, good flow capacity
  • Faulty ignition system: an undamaged spark plug “paired” with the ignition module should ensure stable engine operation

A malfunctioning exhaust system: the cylinder outlet and the muffler should not be clogged with soot. which would cause the weed whacker to “choke”, not develop speed. creating the impression of a faulty carburetor.

If, after checking all of these items remain suspicious on the carburetor, you can proceed to its primary inspection. Conventionally speaking, after unsuccessful attempts to start the engine. unscrew the spark plug and it is “dry”

Disassemble the carburetor should be carried out on a clean, light surface so as not to lose small parts. The disassembly process can be recorded on the photo-video camera, so it is easier to make the reassembly.

Further having unscrewed a nut fastening a cable, we remove it from a throttle boss. The screw marked with an arrow adjusts the idle speed on these carburetors.

This quality screw is adjusted by the manufacturer, it can not “readjust” by itself. In the course of operation it is possible to make adjustments due to wear of the piston group, but it will have “minimal values”.

Stihl FS45 weed eater carburetor repair

As practice shows the factory value of the adjustment. 1.5 turns (If you “razugulirovali” it. screw it completely and unscrew 1.5 turns). At this value, provided the serviceability of nodes trimmer for grass necessarily start. After warming up, you may need to adjust the screw (should be stable at gas rpm))

There is no need to turn it without necessity!

Carburetors of Chinese petrol scrapers. on the left for the engine capacity of 26 and 33cm³, on the right for the engine capacity of 43 and 52cm³. The construction is identical, the difference is noted in the photo. They can be disassembled in the same way.

Immediately examine the condition of the diaphragm blades. They must not be “bent” away from the plane of the carburetor. The diaphragm itself should have no damage.

  • The membrane gasket, too, must not be torn or damaged.
  • The carburetor body is also free from dirt or deposits that could clog the channels and interfere with carburetor operation.
  • The diaphragm should be “intact” and not damaged on its surface.
  • The “heel” of the diaphragm must not “twist”

Pay attention to the “inlet needle area”. If there is any dirt or even a trace of rust. be sure to clean all.

  • Needle stroke must be smooth and free of galling or sticking.
  • To check the needle, we press the “sandwich” against the carburetor. pour petrol (carburetor cleaner) over the needle area (outlet of the diaphragm). (see orange arrow)

Attach a hose to the fuel connection (fig. 12) before starting any work on the saw blade. with the red arrow), blow air in, at the same time inspect the needle for the absence of “bubbles” of air.

If there are no bubbles, the needle holds, no problem. If bubbles are present disassemble further.

  • Unscrew the screw fixing the rocker arm axle.
  • There is a spring under the rocker arm and be careful not to lose any small parts when disassembling.
  • Remove the axle with rocker arm, needle and spring.
  • I would like to note the following: if the “seat” under the needle is broken, no amount of manipulation can not help. you have to replace the carburetor.
  • Let’s continue with.

A very important point to check the condition of the rocker arm axle. To check this: turning the axle in the rocker arm observe. if the axle is no dirt or damage. the rocker arm should remain in place.

  • If the rocker arm moves with the axis, jams and “hinders” the axis to rotate freely, it is necessary to clean the axis.
  • You may try cleaning the axle with gasoline or carburetor cleaner.
  • If it does not help, you will have to resort to mechanical action.
  • Clamp the axis in the chuck of an electric screwdriver and spin at low speed.

Press the fine grit sandpaper (“null grade”) against the axis. Do not get carried away. just a few seconds.

Needle itself, if necessary, can be cleaned in the same way. BUT! Sandpaper should not touch the “tip” of the needle.

  • Moving on.
  • With the carburetor cleaner, just in case, blow out the channels (on the back side of the sandwich)
  • Let’s go further.
  • Blow out the channels with carburetor cleaner, just in case (on the back side of the sandwich)
  • Filter grid must be perfectly clean, in no case allowed to operate the carburetor without it.

And actually the nozzle valve. Exactly because of the diaphragm “sticking” of the valve. no gasoline enters the combustion chamber and the lawnmower does not start.

Proceed as carefully as possible. You can not buy a separate valve on the market. In case of its damage (loss) or malfunction. we will have to replace the carburetor as a whole.

Holding the hose close to the valve. check its work. Blowing and sucking in air. If it is operating correctly

  • If this valve does not work, let’s try to “resuscitate” it.
  • First try to fill it with WD-40.
  • Next, try with a blunt object as much as possible carefully to “loosen” the diaphragm of the valve.
  • If after these manipulations there was no change for the better, the only thing left is to replace the carburetor complete.

Of course you can try to remove the valve membrane, but there is a great chance to damage it. Carefully with a blunt object from the opposite side of the sandwich “push” the diaphragm from its seat in the valve.

How the two-stroke engine works: Brief, but important to get your lawnmower running smoothly

lawnmowers are available with two- or four-stroke internal combustion engines. The difference in design is substantial, but each model runs on a common principle. Chinese trimmer for grass ECO is an example.

engine is called a two-stroke engine, because the full work cycle consists of two strokes: the piston stroke from the upper dead center of the TMT to the lower MMT. It is started the second time it reaches the top position.

chain saws, boat motors and gasoline-powered tools of other similar equipment work in the same way. Let’s take a look at the procedure. We’re supposed to figure it out.

To start the grass trimmer motor, we pull the starter cord. Its pulling unwinds the crankshaft with the flywheel, which creates a moment of inertia. The rotation of the crankshaft by the connecting rod is converted into reciprocating motion of the piston.

The two-stroke motor has four operating cycles:

  • The first movement of the piston from TDC to NDC is accompanied by the injection of a fuel mixture (petrol with oil and air), when the carburettor intake valve opens under the action of the vacuum produced;
  • moving the piston from the NFT to the TDC: the intake and exhaust valves are closed and the working mixture is compressed in an airtight volume;
  • Both valves remain closed. At the top dead center of the piston, the spark leaks through the spark plug contacts.compressed gases explode. Its momentum pushes the piston down and rotates the crankshaft through the connecting rod;
  • the force of inertia of the flywheel directs the piston from the NMT upward: the exhaust valve opens and through it the pressure pushes the combustion products into the exhaust pipe.

All steps are automatic, but are prepared by the operator. If it makes a mistake, the gasoline trimmer won’t start and can break.

grass, trimmer, does, start, again

I will try to explain all these points in more detail.

Check the availability and quality of fuel first

Don’t understand why the lawnmower won’t start, then first make sure there is fuel in the tank. Often beginners forget that it is necessary to pause periodically to refuel the tool with a gasoline-oil mixture. If the mower’s tank is empty, of course it will not start, no matter how much you try to do it.

If there is fuel in the tank, but it is impossible to start the engine of the tool, then do not rush to disassemble the carburetor. Make sure that the grass trimmer‘s engine is started correctly, as indicated in the manual. If the start-up is carried out according to the instructions, then it is important to consider the following points:

  • Do not just use high-quality gasoline with the highest octane rating, but the brand recommended by the manufacturer. And not always such a brand is gasoline AI-95. If you don’t know what gasoline to use for your lawnmower, then choose AI-92
  • The oil should be special. for two-stroke engines. If the lawnmower has a four-stroke motor, then it should be filled with pure gasoline without stirring with oil. You should not economize on the quality of oil for the grass trimmer engine, as well as on gasoline. The higher the quality of the fuel you use, the higher the service life of the engine
  • How to mix the right fuel mixture in a gasoline trimmer. Observations show that the majority of mowers only initially control the process of preparing oil with gasoline for the grass trimmer. The more experience the mower has, the less attention is paid to the process of mixing gasoline and oil for a two-stroke engine. The ratio of petrol and oil should be the same as recommended by the manufacturer. Normally, the ratio is 25 to 1, that is, you need 40 ml of two-stroke oil per 1 liter of gasoline (car engine oil and especially waste must not be used)
  • Correct storage of fuel mixture. It often happens that after a fuel mixture has been made it stands for a long time over 2 weeks. Do not store the ready mix of petrol and oil for a long time, because it causes the oil to precipitate, and thus the properties of both oil products are lost. Even careful stirring after a long storage of the ready mix is not a reason for its further use. This is why it is not recommended to prepare more than 2 liters of mixture at a time

Make sure that all of the above points are met, and only then can you proceed to check the condition of the spark plug. Grass trimmer does not start for a variety of reasons, and most of them can be identified by yourself. It is not practical to dismantle the carburettor if you cannot start the engine. The next step on the way to troubleshooting is to check the condition of the spark plug.

Proper chainsaw care

There are no superfluous phrases in the instruction manual, everything that is offered is aimed at trouble-free operation of the lawnmower. Cleaning all parts after each cycle makes it easy to remove uncured residuals and dirt. Only cooled units should be cleaned. This method is good for air cooling of the engine and gearbox.

Must be fueled with the recommended oil in the manual. If the fuel mixture is left in the fuel tank, the oil will float up and precipitate on the choke when it is started, making it harder to adjust. Mixture can sludge and clog the fuel supply in the carburetor.

When storing equipment for the winter, check and lubricate gearbox and piston system, wrap entire saw in oiled rags and store in a dry place.

It is not permissible and dangerous to the tool and operator’s health to use a metal cord instead of a fishing line. It cuts more efficiently, but it puts more strain on the gearbox and engine. Worn off piece of wire flies at the speed of a bullet when torn off. Efficient mowing may cause engine piston group to wear out soon. For more effective mowing it is suggested to use the “star” line profile.

Lawnmower diagnosis and troubleshooting. video

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Cleaned it, dried it in the hot sun, adjusted the 1mm gap. spark plug, the grasshopper worked like new!

On the black terry deposit on the candle, after cleaning the engine starts and then shuts down immediately, the plug turns out primed.

My problem is that my HYTER lawnmower only starts when I remove the muffler. I also blew and cleaned the muffler, I put the muffler back in place and the lawnmower will not start, WHAT’S wrong with it? Thank you so much in advance.

How to disassemble the carburetor, and which valve to clean

If the brushcutter engine refuses to start, the first thing to do is check the spark plug. If it is completely dry, it means that fuel is not supplied to the combustion chamber and the cause is in the carburetor. Immediately it is worth checking the spark plug as well, to rule it out of the cause on all fronts.

You can also make sure that the engine itself is in good condition. To do this, unscrewing the plug, you need to pour a syringe into the combustion chamber a few milliliters of gasoline. The spark plug is then screwed in and the lawnmower starts. If everything is okay with the motor, it will start for a few seconds. This once again confirms that it makes sense to disassemble the carburetor.

Next, the plastic protective cover is removed along with the air filter. Then use a Phillips screwdriver to remove the two screws holding the choke and carburettor to the engine. Immediately tear off the fuel tubes.

The carburetor is removed and turned over.

On the side of the choke cap unscrew 4 screws with a screwdriver and divide it into two halves. We are interested in the half with the suction. On its inner side there is a valve in the center.

It often gets stuck because after the gasoline evaporates, it has a viscous oil that acts like glue. To check it, you need to put a short thin tube and try to blow air through it. If it’s stuck, it can’t blow in any direction.

A stuck valve can be cleared with a match. It is better not to use toothpicks, because they are sharp and can hurt. You have to put the match lightly on the valve and loosen it. After cleaning it with a match it will be vented.

After removing the blockage you can put the carburetor back on the brushcutter.

The fuel will already be able to flow, so it will work. Cleaning the valve is not the cure-all for all brushcutters that don’t start after idle time, but it helps in 8 out of 10 cases. The remaining 20% is also usually carburetor related, usually the needle.

Dry and wet spark plug what it means and how it affects the engine start

Most tool owners immediately resort to checking the condition of the spark plug contacts. This is done in order to understand from the condition of the spark plug what may be the reason for the inability to start the lawnmower engine. According to the state of the spark plug contacts, you can draw appropriate conclusions about what may be the cause of the malfunction. Diagnosis of the spark plug on the trimmer is performed in the following order:

  • The spark plug is unscrewed, after which it is to be inspected. The ideal condition of the electrodes is if they have brown fouling (brick-colored). If the spark plug is wet and has black or white soot, it indicates related malfunctions
  • If the plug is wet, then there is a portion of unburned fuel in the combustion chamber, which does not need to be drained. Clean and dry the spark plug contacts and then check that it is in good condition. To do this, connect it to a spark plug and place it on the surface of the cylinder. Turn the ignition on, and pull the starter grip lightly. In doing so, the spark plug should give a good and steady spark. If the spark is weak or there is no spark at all, then the spark plug should be replaced
  • The grass trimmer won’t start because of the big gap between the spark plug electrodes. The gap between the electrodes of the spark plug should be between 0.7 to 1 mm. To set the gap use special probes

This is interesting!It is strictly forbidden to dry the spark plug pins by baking them, as this method will lead to parts damage. If the spark is present but the grass trimmer will not start, there is a problem with the fuel mixture in the combustion chamber. To make sure you do this, follow these steps:

  • Draw 20 grams of fuel in a PET bottle cap or syringe
  • Pour it into the combustion chamber through the spark plug hole
  • Screw in the spark plug
  • Put on the candlestick and start the engine

If the lawnmower engine starts after the performed actions, then the cause of the malfunction should be sought directly in the fuel line and carburetor. If the motor does not start even after the performed actions, then it is necessary to check the serviceability of the high-voltage wire. The high-voltage wire is a consumable like the spark plug. If there is suspicion of a faulty armature wire of the grass trimmer, then it should be replaced. If the lawnmower engine cannot be started after these steps, then the following recommendations should be taken into account:

  • If there are doubts about the serviceability of the spark plug and the high-voltage wire, it is recommended to replace them immediately
  • Check the serviceability of spark formation, and if there is no spark on the new spark plug, then the breakdown is related to the ignition unit. the failure of the coil
  • The ignition coil is not repaired, but replaced. If indeed the diagnosis indicates a faulty lawnmower ignition coil, it is not difficult to replace it with your own hands
grass, trimmer, does, start, again

If there is a spark plug, and at the same time it is dry, and the grass trimmer at the same time does not want to start, then move on to check the next node. the air and fuel filters.

This is interesting!If the electrodes of the spark plug have a red or pink color, it indicates that the fuel used contains a large amount of additives. It is necessary to refuse such fuel, having changed a filling station or brand of gasoline.

complex causes of lawnmower failure

If the step-by-step troubleshooting algorithm failed and your grasshopper still won’t start or stalls, it’s worth inspecting the carburetor and the engine itself. A clogged carburetor may be one of the causes of tool instability. Here we can distinguish three main problems:

  • Clogged ducts or nozzles. Clean it all with special washes or with a powerful compressed air jet from a compressor. Do not use needles and wire, because the passage sections can be damaged;
  • Worn carburetor gasket. The way out is to replace the failed gasket;
  • Improper sealing. 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 fall, then some part of the carburetor is faulty. You will have to find it and replace it with a new one.

If everything is okay with the carburetor, the gasoline grass trimmer may not start due to wear of the piston group. If you find chips, scratches or scrapes on the piston or cylinder, they should be replaced. Piston rings must be checked. a slight play of the piston when rocking the crank pin is an indication that it is time to change the rings. This procedure is best left to the specialists of the service center.

Typical malfunctions

The most common breakdowns that occur during the operation of the machine are:

  • the engine does not work, the grass trimmer does not start;
  • The engine can be cranked but does not hold rpm and suddenly stops for no reason;
  • The brushcutter bar is vibrating a lot;
  • The gearbox is severely overheated;
  • the cutting line has a weak rpm.

Before you start repairing, study the manual, which must be included in order to correctly diagnose

The main problems with trimmers: won’t start, vibrates heavily, feels warm to the touch

Grass trimmer, both electric and with internal combustion engine (ICE), is an indispensable tool in the summer and fall for owners of summer houses and private homes.

It easily removes weeds, small bushes and trims the lawn. But, like any technique, grass trimmers fail at the most inopportune moment.

To eliminate malfunctions with their own hands, the user of this equipment must first determine the cause of their occurrence.

The main faults of gasoline and electric trimmers

Lawn mowers and electric grass trimmers, if we do not consider breakdowns associated with the boom and mowing head, the malfunctions mainly occur in the area of the engine.

Breakdowns of gasoline trimmers

Typical gasoline grass trimmer breakdowns that owners of this unit encounter most often are as follows:

  • engine breakage;
  • problems with the carburetor;
  • problems with the fuel supply;
  • muffler failure;
  • gearbox breakage;
  • the starter is broken;
  • problems with the air filter
  • the breather valve in the gas tank is clogged.

Faults of electric trimmers

As the device of an electric mower is much simpler than a mototrimmer, there are few reasons for its failure.

It should be noted that it is better to entrust the elimination of some of them to a specialist.

Basically, the grass trimmer stops working normally in the following cases:

  • electrical cable failure;
  • A faulty control button;
  • burned out motor stator winding;
  • loose connections on the engine.

Why the gasoline trimmer for grass does not start

The reasons why the gasoline trimmer for grass stopped starting, can be different, so you need to conduct a step-by-step diagnosis of the unit.

Fuel tank (fuel quality)

Remember to always check the presence and quality of fuel before starting the machine. In this case, you should not be greedy and save, as well as “smart” about the amount of added oil. You need to do everything according to the manual attached to the machine, because if the piston group fails, its replacement will cost about 70% of the total cost of the grass trimmer.

Fill the fuel up to the level that you will use up during the work. The gasoline left in the tank loses its properties after some time and can damage the engine. So do not prepare any mixture beforehand or in large quantities. If the lawnmower does not start well, try draining the “old” fuel from the tank, and fill it with a freshly prepared mixture.

Important! Filling the machine with fuel of unknown origin is fraught with negative consequences. Gasoline must be of good quality, bought at a gas station and its brand must not be lower than АI-95.

The spark plug and the spark plug passage

So, you’ve changed the fuel, but nothing has changed, and the grass trimmer still won’t start. In this case, it is worth checking the spark plug conduit: whether it is filled with combustible mixture.

grass, trimmer, does, start, again

Often users move the air damper to the “OFF” position when starting, and when the engine starts, do not move it to the “ON” position, after which it stalls.

If you try to start the internal combustion engine again, the spark plug will be flooded with gasoline and startup will be impossible. To diagnose and correct a possible problem in this assembly, do the following.

  • Unscrew the spark plug and wipe it well to dry. When installing the spark plug in the ICE cylinder it must be dry.
  • Drain the fuel that has accumulated there from the combustion chamber. This is done through the hole from which you unscrewed the spark plug.
  • If there is soot on the spark plug electrodes, remove it with either a fine file or a nail file.
  • Remember to adjust the gap between its electrodes before reinstalling the part. The gap on the spark plug should be 1 mm. A coin may be used as a feeler gauge to check the gap.
  • Next, reassemble the block, read the instructions for starting and try to start the engine again.

If the internal combustion engine doesn’t start you need to check the spark. To do this:

  • Unscrew the spark plug;
  • place the cap on the high-voltage wire;
  • touch the metal part of it to the cylinder housing (to ensure contact, you can insert a pipe wrench) as shown in the illustration below;
  • pull the starter cord so that several revolutions of the engine occur.

normally a spark should appear between the electrodes of the spark plug with each piston movement. If there is a spark, then the reason why the engine does not start, you need to look in other parts of the machine.

For a better understanding of how to test the spark plug for spark, you can use this video, where the test is shown on the example of the lawnmower “Soyuz”.

If you get no spark, first check the cable that connects the spark plug to the coil, it may be the problem. You can test it with a tester. if a break in the circuit is found, it will be necessary to replace the high-voltage wire.

Also a faulty ignition coil (magneto) may be the cause of the spark plug failure. The illustration below shows what the coil (magneto) from the gasoline trimmer for grass Patriot (Patriot) looks like.

To rule out a malfunction, you will need to use a tester to check the grass trimmer magneto, namely, its primary and secondary windings. The primary winding resistance should be between 0.4 and 2.0 ohms.

If the device shows 0. it means that in the winding a short circuit occurred, and if infinity is a clear sign of an open circuit. Resistance on the secondary winding should be between 6 and 8 kohms.

On some coils, it can reach a value of 15 kOhm.

Air filter

If your mower does not start or immediately stops after starting, pay attention to the air filter, because it may be blocked, and as a result the air does not flow into the combustion chamber and the fuel does not ignite.

Weedeater 101. The two most common reasons for failure to start.

To check if it’s the filter, remove it and try to start the engine. If it works, then the reason is found. The filter must be replaced or thoroughly rinsed and dried before installation.