STIHL lawnmower not pumping gas

Causes of power loss in the brushcutter. lawn mower does not develop full power

Anyone who owns a dacha or land plot is well aware of the problems of dealing with excess vegetation. Now come to the aid of the trimmer for the grass, which has successfully replaced the usual scythe. This unit is very convenient in operation, but it, as well as any mechanism, tends to fail because of difficult working conditions or incorrect operation. Situations when the grass trimmer does not gain momentum are quite common. To understand this problem, it is necessary to understand some aspects related to the functioning of the device.

All grass trimmers are classified according to the type of power supply: gasoline or electricity (from the network or battery). It should be noted that gasoline mowers are superior to their electric and battery-powered counterparts in many respects. 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 manual mowers is almost the same. the devices are equipped with engines (two- or four-stroke ICE or electric motors), which drive the cutting unit (spool with a fishing line or metal disc). All elements are fixed on a straight or curved boom, including the handle to control the trimmer, on which the main buttons are located.

Since the problem of weak revolutions is more typical for gasoline versions of trimmers, they will be given more attention. So, the lawnmower is very comfortable in operation and unpretentious in maintenance. At the same time, most of its faults are caused by the user’s ignorance of the elementary things that are written about in the instructions. Therefore, before proceeding to operate the unit, it is necessary to carefully study the manufacturer’s manual. In particular, to start the engine, you need to do the following sequential steps:

  • turn on the ignition button;
  • Press the silicone button several times to pump the gasoline;
  • close the air damper;
  • set the throttle lever in the position for high revolutions;
  • first make a slight jerk with the starter handle to feel the resistance of the engine, then yank sharply.

If the lawnmower starts, but stalls, you need to put the air damper in the middle position and try again. When the engine is running, you must turn off the throttle and open the choke because the weed trimmer only runs on air.

Important! Grass trimmer operation mode depends on various environmental influences. In hot weather, the unit should be given more time to cool down. When working in dense or overgrown vegetation, the engine also overheats heavily. Take a five-minute break every 15 to 20 minutes.

Causes of poor grass trimmer rpm

If users complain about the grass trimmer, which does not pick up speed, it means that at idle it works fine, but when you press the gas does not develop the necessary power. This can occur as a result of long idle time without activity. These problems are typical for gasoline-driven machines, including Husqvarna 128r, STIHL FS 38 and Hitachi of different modifications.

Working with the trimmer, you need to monitor its behavior all the time. a drop in rpm and unusual noises signal a problem in the unit. Sometimes you give the gas, and the grass trimmer floats. In such cases, the work should immediately suspend, let the mechanism cool down and begin to search for possible problems. They can be of different nature, both technological plan, and external factors related to the conditions and features of using the machine.

External factors

Several factors, unrelated to mower failure, can cause the mower’s RPM to decrease:

  • contamination of the filter due to the ingress of dirt and dust particles;
  • use of poor quality fuel;
  • Incorrectly prepared mixture (important for trimmers with two-stroke gasoline motors);
  • Contamination of the muffler screen by vegetation particles, soil elements, and other objects.

In the second and third cases there is formation of soot in the combustion chamber and clogging of carburetor elements.

Technical faults

Technical problems with the lawnmower mainly occur in the fuel supply and ignition system. You can deal with them on your own.

  • When the hand mower won’t start or stalls, the problem could be related to the spark plug. Dark soot indicates poor carburetor adjustment and poor quality gasoline.
  • The cause of incorrect operation of the grass trimmer may be a clogged fuel hose. The filters also frequently become clogged.
  • Another problem within the machine is that the muffler is covered in soot. It causes the grass trimmer’s RPM to drop drastically. The way out is to clean the muffler.
stihl, lawnmower

Important! If the machine does not run due to engine faults, there can be serious problems. In this case, the only damage that can be solved by hand is the destruction of the piston rings. For more serious engine problems, if there is no warranty, you should be prepared to visit a workshop.

How to Start Diagnosing Your Grasshopper

If the lawn mower does not start or immediately stops after starting, you need to check all the main assemblies and units in sequence. The check algorithm is as follows:

  • Fuel tank (fuel quality);
  • The spark plug and spark plug passage;
  • Air filter;
  • Fuel filter;
  • Breather filter;
  • Exhaust port.

These assemblies are most often the source of major problems, which can be corrected after a thorough inspection.

Checking the fuel mixture

Before starting the engine of a gasoline grasshopper, check the presence and quality of the fuel mixture. Don’t save, don’t be greedy and “don’t be smart” in this matter. Repairing or replacing the piston group will cost you too much (sometimes up to 70% of the cost of a new tool). The oil-fuel mixture must be prepared strictly according to the instructions. Calculate its amount from real needs. Excessive gasoline that remains after work loses its properties over time.

Carry out diagnostics of a spark plug and spark plug passage

If the quality of the fuel mixture is beyond a doubt and the lawnmower stops when starting, the cause may be a primed spark plug. A simple spark plug wrench (every motorist should have one) and a spare spark plug will do the job.

  • Unscrew the spark plug and wipe it clean;
  • We dry it thoroughly (you should not burn it);
  • Drain the excess fuel in the chamber through the spark plug hole and dry it;
  • Clean the old spark plug from soot with a file or a lady’s file;
  • We set the gap with a distance of 1 mm (you can check it with any coin);
  • Put everything back in place and try to start the weed trimmer.

Dry the channel not less than 30-40 minutes. Otherwise there is a risk of flooding the spark plug again.

If the spark plug works, the socket where it is located is completely dry, but the lawnmower does not want to start, lubricate the threaded joint with petrol. It should be slightly moistened. No matter how great the spark may be, there is nothing to ignite in the dry chamber.

If the grass trimmer engine still does not start, you should rule out such a cause as a lack of spark due to poor contact between the spark plugs and the high-voltage wire. If the connection is good, but there is still no spark, most likely the ignition unit is “broken”. You can’t do without a handyman here. к. The part is not repairable, but sold as a whole unit.

Diagnosis of lawnmower filters

Another reason why your petrol grasshopper mower malfunctions could be the air filter. To rule it out, try to remove the filter and start the grass trimmer without it. If it works, then you will have to change the air filter for a new one, or at least blow and thoroughly clean the old one.

The gasoline grass trimmer may not start due to a dirty fuel filter. This is the next step of our algorithm. Here we check the condition of the filter element and, if necessary, replace it with a new one. When changing, be careful not to leave the intake tube completely without filter, it is forbidden by any instruction manual. Haste may result in damage to the engine piston group.

Breather and exhaust port

Often “delicate” brand-name models don’t start and stop due to a clogged breather valve. The main function of this element is to equalize pressure in the gas tank. If this element is clogged, it creates a vacuum in the tank, blocking the fuel supply. The problem can be corrected by cleaning the breather plug. An ordinary needle can be used for cleaning.

Normal operation of cos with internal combustion engines may be disturbed due to dirt in the exhaust channel or clogging of the silencer mesh. Such problem is encountered on older models. The problem can be solved by the traditional cleaning and removal of the anti-sparking grid.

trimmer for grass, both electric and with a combustion engine (ICE), is an indispensable tool in the summer and fall for owners of summer houses and private homes. With its help, weeds, small bushes, and lawn trimming are easily removed. But like any technique, grass trimmers fail at the most inopportune moment. To fix the problem with your own hands, the user of this equipment must first determine the cause of their occurrence.

If the step-by-step algorithm of troubleshooting did not yield results, and your grass trimmer still does not start or stops, it is worth inspecting the carburetor and the engine itself. A clogged carburetor can be one of the causes of unstable operation of the tool. Here we can distinguish three main problems:

  • Clogged ducts or jets. Clean it all with special washes or blown with a powerful jet of compressed air from a compressor. Do not use needles and wire, as the passage sections may be damaged;
  • Wear of the carburetor gasket. The solution is to replace the failed gasket;
  • Poor 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 drop, then some part of the carburetor is defective. 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 a piston or cylinder has a chip, scratch, or scrape, it should be replaced. Piston rings must be checked. A small backlash of the piston when rocking the connecting rod indicates that it is time to change the rings. This procedure is best entrusted to service center specialists.

Repair of chain saws with their own hands

Some problems with the brushcutter appear because of incorrectly prepared fuel consistency. In two-stroke engines, the lubrication is done with special oil (not ordinary motor oil)!) mixed with petrol. If oil is not mixed with petrol, the lawnmower will fail very quickly. Mix the oil/gasoline in the proportions indicated in the grass trimmer’s manual. As a rule it is 1:40 as it is also called 1:50.

It’s not uncommon that the question arises: the proportion 1:50 is how much oil and gasoline?

Numbers are as follows: one part of oil takes 50 parts of gasoline. From here: 1000 ml (1 liter of gasoline) divided by 50, we get 20 ml, in other words 1:50.

Thus it is of course possible to calculate the composition of fuel consistence (gasoline/oil) in all proportions. To add oil to petrol without “by eye”, of course I recommend to take a 20 ml syringe of honey, put oil in it and “inject” it into a container for making fuel consistency.

A small amount of oil mixed with gasoline, leads to increased wear of the cylinder piston group. Too much oil in the consistence is not so fatal, but harmful. Sometimes there is coking of piston rings, sharp formation of sludge in the combustion chamber, reduction of engine power. And additionally, the muffler mesh screen gets clogged. Therefore, some users (after the warranty period on the grass trimmer) advise to dismantle it.

The numbers are as follows: 50 parts of petrol for one part of oil. Hence: 1000 ml (1 liter of gasoline) divided by 50, you get 20 ml, in other words 1:50.

To calculate the composition of fuel consistence (petrol/oil) in all proportions. In order to add oil to gasoline not “by eye”, of course, it is recommended to take a 20 ml syringe of honey, fill it with oil and “inject” it into a container for making fuel consistency.

Small amount of oil mixed with gasoline, leads to increased wear of the cylinder-piston group. Too much oil in the consistency is not that fatal, but it is harmful. Sometimes there is a corking of piston rings, rapid formation of carbon deposits in the combustion chamber, the decline in engine power. In addition, it causes the silencer mesh screen to get clogged. Because some users (after the warranty period on the trimmer for grass) advise to dismantle it.

The grass trimmer leaks petrol.

The gasoline used in the brushcutter is AI 92. Petrol brand is written precisely in the user manual. It makes no sense to try to “force” the engine, there pouring 95-th gasoline. This leads to overheating, unbalanced operation of the grass trimmer and breakage.

It is not recommended to leave fuel in the trimmer’s fuel tank when it is not in use for an extended period of time. It is best to finish the day’s work with one hundred percent of the mixture. If you do not, then, as overnight, gasoline from the engine will fly away, and a narrow film of oil remains, the carburetor jets will be clogged. This will make it harder to start the engine the next time.

You should also be careful when storing fuel. Probably fill up the gasoline in a plastic water bottle. It’s worth doing?

grass trimmer leaks gasoline.

The gasoline used in the brushcutter is AI 92. What kind of gasoline is used on your power tool? It does not make sense to try to “force” the engine by pouring in the 95th gasoline. This leads to overheating, unbalanced operation of the grass trimmer and breakage.

It is not recommended to leave fuel in the trimmer’s tank during a long work break. The best way to finish a day’s work is to get 100% of the mixture out. If this is not done, then, since overnight the gasoline from the motor will volatilize, and a narrow film of oil remains, the carburetor jets will be clogged. This will cause difficulties with the next engine start.

It is also necessary to follow the safety rules for storing fuel. Probably fill up gasoline in a plastic water bottle. Worth doing?

Under no circumstances should you store gasoline in a plastic container from the water. Static charge builds up while mixing the fuel consistency and you can “catch” a spark.

That’s why gas stations don’t allow gasoline in plastic cans, only in iron cans. Before pouring gasoline into the iron canister, it is better to put it on the ground, so it removes static from the body.

But there are situations when ordinary manipulation with a brushcutter does not help. The engine won’t start anyway. In this case, check the power and ignition system, following the rule “the engine does not run if there is nothing to burn or nothing to ignite”.

The chain saw likes cleanliness. It is necessary to monitor the cleanliness of the air filter and fuel. Gasoline, bought at the gas station, is better to stand for 2 days and pass it through a simple filter. a piece of baize cloth.

Check the electrical equipment as follows:

Unscrew the spark plug, inspect the gap between the electrodes. Set the correct gap between the electrodes can be “grandfather’s” way. Take a razor blade, break it in half and put the home-made probe between the electrodes. If the blades fit snugly, then the gap is perfect.

put the cap of high-voltage wire on the spark plug and lean it against metal surface of the engine. Yank the starter a few times. If the spark is well struck to one point, the gap is set correctly. If not. the spark is weak or “wandering”, it is necessary to re-adjust the electrode gap.

Also in the electrical equipment may be a punctured ignition coil. In this case, the lawnmower does not start or starts and works intermittently, and then shuts down, or on the “hot” does not start at all.

Check the coil in the same way as with the spark plug: Remove the spark plug and hold it against the carburetor. If there is no spark when the starter jerk, or it appears intermittently, you should change the coil.

Why not running in STIHL power tools??

The times of the first chainsaws (“Ural” and “Druzhba”) in our country are gone. Gone are the days of asking “How do I run in and out of a chainsaw?

Do NOT run in new STIHL power tools under any circumstances.

All gasoline equipment is run-in at the factory.

STIHL chain saws are usually taken to the service department after a so-called “break-in period”.

It is not advised to let STIHL machines run freely at all.

The 2-stroke engines do not burn the fuel mix completely at idle speed and the engine will get caked.

stihl, lawnmower

Simple advice. Always apply gas to your STIHL chain saw. STIHL machines like to run! The only limitation for new chain saws. First 2 or 3 tanks, keep the throttle to a minimum, let the machine run in at half throttle.

However, if you get stuck in a log, go full throttle.

We have now established that STIHL machines do not need a running-in period. Completely! No. Even if you are told to “run in” the machine by “experienced guys” at the market where you buy it.

By the way if you buy a STIHL tool on the market you have a 99,9 % chance that you are not buying a STIHL tool but a Chinese copy of the original.

  • First of all, this tool is sold only at official points of sale, through the manufacturer’s website and a small number of certified partner websites.
  • Secondly, no sales manager is going to tell you how to run your STIHL chain saw in cold start.
stihl, lawnmower

Why? Let’s have a closer look

The chainsaw comes off the assembly line and is taken to the engine room where it is assembled, the oil and fuel mixture are filled, tested, serviced and fixed in a special chamber for running-in gasoline tools, which is located there, at the factory, next to the conveyor. During the specified time it goes through a “hot” running-in period until all the components and mechanisms are properly adjusted to one another. this is actually the purpose of the running-in period and the best way to run in the STIHL chain saw.

So as soon as you fill it up with fuel and oil, you’re off! Work for 10-15 minutes, 5 minutes rest, then 15-30 minutes, and then rest again. After 3 to 5 tanks of gasoline, it will get the maximum power, and you can run the regulation time on the technical passport.

Yes, some manufacturers may recommend it, but in this case with STIHL it will only be a waste of time and your resources (effort, fuel, oil).

We thank you for choosing our machines and wish you pleasant and fruitful work!

What to do if the lawnmower stops when you step on the gas

Most often, in the periods when the lawnmower stalls when adding gas, the cause will be the air damper, or rather, its condition: it is clogged. The part is structurally located where the received fuel is atomized behind it, and accordingly, the product collects all the inclusions in the poor-quality gasoline. To solve the problem, you just need to clean it. The same situation can occur with a clogged filter, but it is eliminated in the same way. To summarize, let’s specify the reasons that lead to the stalled condition when the instrument is pressed on the gas:

  • clogged air flap;
  • clogged fuel filter, and when you give gas. it is especially noticeable;
  • there is air leakage by the crankshaft oil seals;
  • the gasket between the cylinder and the carburettor is damaged.

When you have cleaned, flushed and purged the elements, but again the lawnmower stalls when you press the gas

  • Malfunction of the carburetor metering system.
  • Cracks in the fuel hose caused air leakage.
  • Problems with oil seals.

During operation situations occur when the lawnmower at high revolutions is subjected to a similar abrupt stop. It occurs for the following reasons

  • due to problems with the circulation of the fuel mixture;
  • Air leakage;
  • The fuel intake hose is poorly connected or cracked and cannot be operated;
  • The valve in the gasoline tank lid is stuck or clogged;
  • The carburetor is out of alignment.

How to care for the cutting attachments on your lawnmower

The saw headset dulls or wears out over time. Working with the tool becomes strenuous, the load increases, the quality of mowing deteriorates. Metal blades are sharpened, plastic blades are replaced.

If the cutting tool is a line for the trimmer, it gradually wears out, and a new material is installed in the spool. The principle of the line torch is the gradual unwinding of the coil by centrifugal force. When in contact with the grass, the line for the trimmer is abraded, from the spool is fed gradually. A special winding is necessary so that the two cutting elements come out simultaneously and do not get tangled with each other.

The illustration shows how to correctly wind the line for the trimmer on the mower spool. Before winding a new line for the trimmer it is necessary to:

  • Having unscrewed the nozzle, carefully remove the cover by holding the spring with your hand;
  • Remove the old line scraps from the reel;
  • Measure 5 meters of new string and fold it in half;
  • in the spool guides under the 2 ends, hook the middle part to the notch and wind in the direction of the arrows for each half of the string;
  • to wind the remaining 20 cm through the notches on opposite ends of the spool;
  • install the spring and the washers, lead the line ends outwards, close the reel with the cover.

For a better understanding of how to change the line for the trimmer on a chain saw, watch the video.