Does not pump the carburetor on the trimmer
Carburetor cannot be adjusted
The fact that the adjustment is too coarse (it is not possible to accurately set the parameters) are to blame for the springs on the adjusting screws. A lawn mower or trimmer manufacturer may supply unnecessarily thick and stiff springs. You can find others either in workshops where similar equipment is repaired, or purchased from any dealer or official representative of the company that produced the motor for your trimmer or power scythe.
lawn mower (lawn mower) contains a base. a body made of aluminum, which houses the rest of the parts, working harmoniously as a whole. There is a diffuser in the carburetor body. a stroke with internal channels through which air is pumped.
The larger the cross-section of the diffuser, the more actively oxygen is supplied together with air. an oxidizer, in which the fuel is burned (gasoline-oil mixture).
Channels branching off from the diffuser stroke deliver fuel, with which the forced air mixes, entraining gasoline vapors with it. Outside the main carburetor compartment are located:
- mini fuel pump;
- unit regulating the mixing of fuel with air.
The latter forms the very explosive mixture ignited in the carburetor combustion chamber.
Trimmer doesn’t start, carb rebuild.
Damper worn out
The throttle and air damper become unusable due to the ingress of dust, metal particles, etc. with the air flow. Damaged dampers are similar to parts that have been blasted with sand. Due to wear on the dampers, the efficiency of the motor decreases, and breakdowns are detected. Piston and cylinder wear out.
The dampers become unusable due to improper maintenance of the air filter or its breakdown.
In some cases, this filter is simply not suitable for your lawn mower or trimmer model. In the end, the motor shaft will suffer. its pieces fall into the engine channels, causing the piston to be broken.
Failure of the adjusting lever
The wear of the contact edge of the lever is a consequence of an incompletely purified fuel, into which grains of sand or particles of clay, metal, or other inclusions that are not soluble in liquid hydrocarbons have gotten. There is a problem with fuel injection, the engine does not function without load.
Adjustment diaphragm damaged
The membrane often deforms (sometimes breaks) due to the continuous operation of the lawn mower or trimmer for several hours. If you abuse this “shock” mode of operation, membrane damage occurs more often. New breakdowns will sprinkle like a cornucopia:
- the piston will break;
- the number of unsuccessful engine start attempts will increase dramatically;
- the fuel mixture contains too little gasoline;
- useful (thermal) power will sharply drop.
Adjustment lever defective
This breakage occurs when the contact surface of the lever wears out.
The abrasion of the contact surface occurs due to the presence of abrasive particles in the gasoline or due to strong vibration of the engine during operation. This defect in the adjusting lever causes problems with the intake, as well as improper idling of the engine.
Clogged control cavity
If dirt accumulates in the adjustment cavity, the inlet needle cannot close the hole tightly and a lot of fuel pours into the chamber.
This causes over-enrichment of the fuel and the engine starts to malfunction. It is necessary to disassemble the carburetor and clean the cavity of the control membrane.
How does a lawn mowers carburetor work or how it works
The carburetor adjustment of the Chinese lawn mowers is completely identical to the adjustment of the European, Russian and manufacturer’s lawn mowers. To cope with the task of adjusting the carburetor on lawn mowers and petrol trimmers, you need to understand the principle of their operation. How the carburetor works on a lawn mower is described step by step and accessible below.
- The carburetor of lawn mowers begins with fuel supply through the channel, as shown in the diagram
- Suction of fuel into the carburetor takes place using a pulse channel connected to the crankcase. Due to the rarefaction of air, the flexible membrane moves at number 4 in the diagram above.
- Fuel is supplied through valves 3 and 5. Valve 3 is an inlet valve, due to which fuel is supplied to the under-membrane space, and valve 5 is an outlet
- Further, the fuel moves along the channel and, passing through the fine filter, reaches the needle valve 14
- The needle valve is connected by means of a lever to the control diaphragm 18
- The needle valve is actuated by acting on the diaphragm. When it is necessary to pump fuel to start the engine, it is necessary to act on the soft cover of the hand pump. Upon exposure, the needle opens, and the chamber is filled with a fuel mixture.
- When the engine starts (cold), the opening of the needle occurs due to the vacuum with the air damper closed. This vacuum acts through the idle and high speed nozzles on the diaphragm 18
- The membrane acts through a lever on the needle valve, whereby the chamber is filled
- After starting the engine, the air damper opens, as a result of which the engine runs on a lean mixture, as the fuel mixes with air
- When the chamber is full, the fuel mixture is supplied (sucked in) through the idle and medium speed nozzles (when the engine is running)
- At the same time, the throttle valve is displaced from the initial position by 10-15 degrees
- When the work is carried out under load, the fuel begins to flow into the chamber through the high speed jet, and at the same time the throttle valve rotates through an angle of up to 90 degrees (depending on the force of pressing the gas). In all operating modes, the air damper must be open, through which the fuel is mixed with air, and thereby the mixture in the cylinder is ignited.
Below is a diagram of the principle of operation of the lawn mower carburetor. Based on the diagram, you can not only figure out the principle of operation, but also identify breakdowns and other malfunctions of the mechanism.
When operating the tool, it is necessary to take into account the presence of one more jet. This jet is located between the idle and full power channels. It is necessary in order to exclude a strong depletion of the mixture, which happens when the engine is running at partial load. In such a situation, the occurrence of a badass couple is not excluded. Through an additional channel (jet), fuel is sucked into the chamber, whereby the fuel-air mixture is enriched. The diagram below shows an additional jet, which is indicated by the number 1.
Having an idea of the design of the membrane carburetor for lawn mowers and the principle of operation, it will not be difficult to customize it yourself. The lawn mowers use adjusting screws to adjust the carburetor. The diagram above shows two adjustment screws, however most modern petrol trim models have three screws. The presence of three adjusting screws allows for more accurate adjustment, while achieving stable and uninterrupted operation of the internal combustion engine.
Intake control lever is sticking
Jamming of the adjusting lever is a consequence of its incorrect installation, accidental bending. The contacting face will get the wrong position. This will disrupt the additional injection of gas.
Defective fuel pump
The most repetitive breakdown is wear and tear of the diaphragm. As a result, its non-conformity. The fuel passages are not sealed at certain stages in the engine cycle. The reasons are as follows:
- you have been working on the lawn mower or trimmer for too long without interruption;
- fueled with low-quality fuel;
- exhaust gases enter the impulse channel.
A deformed membrane is fraught with several bad consequences:
- not enough gasoline or oxygen in the generated combustible mixture;
- the motor starts after 10 or more unsuccessful attempts;
- the engine knocks, clinks during operation, etc.;
- the working piston is deformed.
Primer. a hand-held mini-pump for forced pumping of fuel into the carburetor. For a successful start of the engine, it may be necessary to pump 20 ml of gasoline manually.
Adjusting the Husqvarna carburetor
Before adjusting Husqvarna, do trimmer maintenance (wash mower and engine, replace spark plug, fix minor defects).
Be sure to wash the foam air filter element. Wash the element in warm water and soap, then wring out and dry (or replace if old or damaged).
Note: If you adjust a Husqvarna carburetor with a dirty air filter, the fuel mixture will be much leaner after cleaning the air filter (which can lead to poor performance or even engine damage).
Install a trimmer head with a cord of maximum diameter and standard length (up to the cutter blade in additional protection) to put a load on the engine when adjusting the high speed screw of the Husqvarna carburetor.
Start the mower according to the Husqvarna Manual and warm up for 10 minutes (if the trimmer head rotates at idle speed, the idle screw, i.e.
lower, must be turned counterclockwise until the rotation of the trimmer head stops).
Carefully turn both needles (right and left) to the midpoint between fully unscrewed and fully screwed in (do not turn by the stopper !, this could damage the Husqvarna engine)
There are three adjusting screws for adjusting the Husqvarna carburetor: right, left and bottom.
1) Right screw L. regulates the enrichment of the mixture at low speeds (controlled first):
Find the maximum idle speed by slowly turning the right screw to the right and left.
Then turn this screw ¼ turn counterclockwise.
Note: From the Husqvarna factory, the right screw has been completely removed (0.5 turn). He is now looking at 11 o’clock. 2) Bottom screw T. adjust idle speed of the Husqvarna engine (if necessary): turning the screw clockwise increases idle speed, counterclockwise decreases idle speed.
It is considered correct to adjust the idle speed when:
- Cold engine idling steadily.
- A hot engine does not idle too high.
- There is sufficient headroom before the trimmer head starts rotating.
- The engine runs stably in any position (for example, when the knife is suddenly lowered).
Note: From the factory (Husqvarna), the idle screw from fully tightened was unscrewed by 8 full revolutions and “2 hours” (now it remains). Recommended idle speed for Husqvarna lawn mowers is 2.900 rpm. 3) Left screw H. adjusts the enrichment of the mixture at high rpm (adjustable last).
It regulates maximum rpm, engine power, temperature and fuel consumption.
Note: The Husqvarna engine must not run at full speed for more than 10 seconds.!
- Open the throttle fully (full throttle) and slowly turn the left screw clockwise until the Husqvarna engine speed is reduced (audibly).
- Then turn the left screw very slowly counterclockwise until the engine runs unevenly.
- Then turn the propeller back a small amount clockwise slowly until the Husqvarna engine runs smoothly.
This completes the Husqvarna adjustment.
Note: Recommended maximum Husqvarna engine speed is 11.500 rpm.
The maximum engine power output of the Husqvarna 333R lawnmower is 1.6 kW (2.1 HP) at 8,400 rpm.
Note: On a new Husqvarna trimmer from the factory (Husqvarna), the left screw was completely unscrewed (0.5 turn) and blocked (covered) with hard plastic which I drilled out at the end of the warranty period. Now the left screw (as well as the right one) looks at approximately “11 o’clock”.
Lawn mowers device
The device of the Stihl FS 55 lawn mowers should be clear to you if you plan to operate the equipment, let alone repair it. The internal combustion engine in this unit is almost the same as in a chainsaw. But the tire is the latter fixed to the motor reducer by a long tubular rod. Inside there is a shaft that transmits torque from the motor to the working tool. This design is suspended from a strap that is thrown over the shoulder. This allows you to hold the tool on the weight, which is fundamentally with the sensitive weight of the chainsaw.
A handle is fixed to the bar of the unit, with the help of it you can move the end of the bar with the working equipment. the Stihl FS 55 lawn mower, the repair summary of which is presented in the article, has a protective shield in the form of a casing on the human side, which excludes injuries during operation. The tool itself is a round drum with thick line coming out of the holes on both sides. Adjusting the carburetor and chainsaw repair lawn mowers Stihl stihl fs55 fs 38 carburetor. When the drum spins, the line is pulled by centrifugal force and hits the grass, chopping it.
Lawnmower “Stihl FS 55”, the technical properties of which will be presented to your attention below, has a wear-resistant nylon line. Features of the Stihl fs 38 lawn mowers, carburetor adjustment of the Stihl fs 38 lawn mowers. It is renewed from time to time by unwinding the reel, which is inside the drum.