Pacman Trimmer Carburetor Screwdriver
The stable and effective operation of the household trimmer is largely dependent on the quality of the fuel used by its operator. The filled fuel mixture must be enriched with air. For this, the built-in carburetor is responsible for this in the basic lawn mowing device. This node is one of the main elements of the braid, so the operator must constantly monitor its serviceability and settings. Otherwise, the trimmer will lose its performance and may completely fail.
The device of the carburetor lawn mowers
The standard design of any gas trimmer must include a fuel system, the basis of which is the action of a standard carburetor. Its structure and initial principle of operation are almost the same for all lawn mowers, regardless of their design features and purpose.
The lawn mowers carburetor consists of an all-metal aluminum housing that protects the internal components of the assembly from moisture, small debris and dust. A built-in diffuser is provided in the lower part of the body, the second name of which is “Venturi nozzle”. The main function of this standard part is to supply air in the amount required by the fuel assembly to enrich the fuel. The diffuser operates according to a simple principle: the smaller its diameter becomes, the more intensively the air is absorbed. This is due to the fact that in the zone of the smallest diameter the level of air discharge becomes maximum.
The upper part of the built-in factory diffuser is pre-equipped with fuel pipes, through which, under the influence of air, the fuel mixture is drawn in. Other carburetor parts: regular adjusting screws and a fuel pump, can be located both inside and outside the carburetor.
The carburetor of the lawn mowers includes a throttle, the main task of which is to regulate the amount of intake air. The greater the amount of air, the higher the rated power of the trimmer power unit. Another function of the damper is to facilitate the cold start of the engine. If the lawn mowing is started for the first time after a long period of inactivity, the shutter must be closed. Immediately after starting the motor, the part must be opened, otherwise the engine will die out.
The carburetor for the trimmer is equipped with a pulse channel that connects the internal cavity of the ICE crankcase with the pulse chamber of the pump. The piston located in the cylinder of the motor creates a reciprocating motion, which leads to gradual changes in pressure inside the crankcase. At the same time, the membrane is driven. Thus, the action of the pump is fully synchronized with the operation of the power unit.
The membrane of a regular carburetor takes an active part in fuel suction. It enters the fuel assembly through the fitting. After that, the fuel passes through the built-in intake and exhaust valves, then through the strainer and the fuel pipe. Then the fuel flows next to the needle and gradually fills the chamber equipped with a control membrane.
The regular valve of the trimmer carburetor is connected to the membrane using a lever. Below the built-in membrane is a cavity into which air is drawn in through a special opening.
The carburetor for lawn mowers works on this principle in stages. This ensures uninterrupted operation of the fuel unit and uninterrupted supply of fuel to the cylinder of a standard power unit.
When is the carburetor adjustment of a household trimmer required?
Adjust the built-in trimmer carburetor when:
- Running-in of a new engine, during which from 4 to 5 liters of fuel mixture were used;
- Sudden changes in weather;
- Changes in rarefaction of air. For example, when the lawn mowing is often used in mountainous areas;
- Long simple trimmer;
- Intensive growth of loads on the power unit of lawn mowers;
- Arbitrary unscrewing of the carburetor’s built-in adjusting screws. This becomes the cause of increased vibration of the internal combustion engine;
- Changing the quality of the components of the fuel mixture;
- Fuel transfusion with a carburetor, resulting in an increase in fuel consumption;
- Regular appearance of a thick layer of tarry deposits and soot on the surface of the electrodes of a regular trimmer spark plug;
- Engine start and its arbitrary shutdown or a slow set of revolutions;
- The lack of fuel in the cylinder of the power unit;
- Increase in exhaust emissions.
The lack of timely adjustment of the carburetor threatens serious damage to the trimmer, up to the complete failure of its factory engine.
DIY carburetor adjustment
Periodic adjustment of the trimmer carburetor should be performed on a serviced and fully functional power unit. Before starting the procedure, the operator must thoroughly rinse the engine parts and inspect its CPG for any burrs or other defects. In addition, you will need to clean or replace the spark plug, as well as rinse the filter elements in the construction of the lawn mowers.
During carburetor adjustment, the lawn mowing engine must run under a certain load. It is best to install a cord of the appropriate diameter or cutting knives on the trimmer.
After mounting the cutting organs, the operator should start the internal combustion engine trimmer and leave it to work for about 10 minutes. If during operation of the power unit at idle it was noticed that the cord or knife rotate, then you need to reduce the speed created by the motor. To do this, turn the lower control, often denoted by the letter “T”, to the left, until the installed cutting unit stops completely.
A further configuration of the fuel assembly is as follows:
- The “L” regulator, located on the right, is responsible for enriching the fuel mixture with air while the engine is operating at low revs. The position of this screw must be set first. To do this, the operator will need to achieve maximum engine speed when idling. For this you need to turn the screw “L” in turn to the right or left side. Once the maximum speed is reached, the screw will need to be rotated 1/2 turn to the left;
- Screw “T” or “LA” is required to adjust the idle speed. During its rotation to the left, the revolutions of the power unit will decrease, and when turning to the right. Accordingly, increase;
- The “H” regulator, provided on the left, is responsible for enriching the fuel mixture with air during the operation of the engine trimmer at high speeds. This screw is also needed to adjust motor power and fuel consumption. Its position is adjusted by turning the screw to the right or left side until the maximum permissible engine speed is reached. After that, screw “H” will need to be turned 1/2 turn to the left.
The sequential implementation of these actions will allow you to correctly configure the trimmer fuel assembly, without the risk of exceeding the permissible load on its main operating mechanisms.
The increased fuel consumption and the rapid formation of soot on the lawn mowing candles when using a correctly prepared fuel mixture indicate the need for carburetor adjustment. This describes how to set trimmers with carburetors that have one screw for adjusting the fuel supply.
Flush the air filter before adjusting the carburetor. It is recommended to rinse it after every 10 hours of operation. After that, you can begin to adjust. The example photograph shows the carburetor of the gasoline trimmer PRORAB-8406. The numbers indicate the adjusting screws that we will use.
Prorab-8406 gas trimmer carburetor adjusting screws
Purpose of adjusting screws:
- Fuel mixture adjusting screw.
- Idle adjustment screw.
- The screw limits the maximum speed.
Start the lawn mower and wait until it warms up.
Start slowly tightening the fuel mixture adjusting screw until the engine stalls or stalls unless you catch the moment. Then unscrew the screw a quarter of a turn if the engine is not dead, or half a turn if it is dead. Start the stalled engine. Check, by opening the throttle, how the engine accelerates. Continue to loosen screw # 1 a quarter of a turn until the engine starts to confidently gain high revs when progazovka. This will be the moment of the most economical stable engine operation. At the PRORAB-8406 gas trimmer, the adjusting screws are turned clockwise, unscrewed. Against, for some other brands the lawn mowing may be vice versa.
We proceed to adjust the low speed. Screw number 2 restricts the return movement of the throttle lever. By wrapping it, we increase idle speed, unscrewing. Reduce it. Adjust so that the engine runs confidently at low speeds and even slightly faster (for a better start), but so that the reel with fishing line or knife does not rotate, and before starting to rotate, there is a sufficient margin of speed. If the engine starts poorly, still increase idle speed.
Maximum speed limit
After adjusting the flow of the fuel mixture and low revs, check how the lawn mowing engine will operate at maximum speed. If necessary, limit the maximum speed to the required level using the No. 3 hollow screw. Loosen the locking nut and screw in to decrease the maximum speed or unscrew to increase. After adjustment, tighten the nut. Setting the maximum speed is necessary to protect the trimmer motor from overheating and the ability to use the release key lock to reduce fatigue of the right hand.
In the future, it may be necessary to adjust the trimmer carburetor. For example, if the engine, when operating at full load, starts to pick up revs poorly, loosen screw No. 1 another quarter of a turn. If it is difficult to start, increase the idle speed. Weather conditions and the quality of the fuel mixture can affect the operation of lawn mowers. The vibration can also make the adjusting screws turn themselves.
The spring may interfere
My first attempt to adjust the carburetor of the lawn mowers did not work, as the spring of the fuel mixture adjustment screw prevented it. The factory spring turned out to be too thick in a compressed state and did not give the opportunity to reduce the fuel supply to the required level. I had to pick up another spring and continue adjusting after replacing it.
Spring mixture adjustment screw
In the photo above, the factory spring, below the adjustment screw with a selected spring. I am writing about this, because I’m not sure that this is an isolated case, and someone else may encounter the same situation.
From personal experience
Lawn mowing or trimmer
A trimmer is a broader concept than a lawn mow (lawn mow), since it can also be electric. A gas trimmer and a lawn mower are one and the same.
Some authors claim that the trimmer is a weaker tool, in contrast to the more powerful lawn mowers, which can be used to mow shrubs. Personally, I have a tool with a maximum power of 1.7 kW and capable of mowing a small shrub up to 10 mm thick, as stated in the instructions. The user manual is called “Petrol trimmer”.
Fuel mix ratio
I read somewhere that if in the instruction manual for lawn mowers and on the canister with oil different proportions of the preparation of the fuel mixture are indicated, the proportion indicated in the manual should be used.
It did so for a long time. Excess oil flowed from the engine to the gas tank and soot was constantly forming on the candle, since the manual indicated the proportion for the engine being run in 1:25, and on the canister. 1:50. After the transition to a proportion of 1:50, the appearance of oil drips stopped. The candle continued to burn, but with less intensity (the carburetor was not yet adjusted).
Until now, some users of gasoline tools determine the proportion of the fuel mixture “by eye”. If during the preparation of the mixture the amount of oil is underestimated, after some time an extraneous sound may appear immediately after the engine starts, gradually disappearing during warming up, and the engine stops with a sharp jerk. Continued operation of the trimmer in this mode will lead to its failure.
In the worst days of working with a trimmer with an unregulated carburetor, the engine stopped starting after using each fuel tank. And only after cleaning the candles from soot could we continue to work.
To clean the electrodes, fine sandpaper was used, and to clean the space between the insulator and the body, a thin clerical clip with a bent end was used. First, the electrodes were wiped off with a lot of dirt with a rag, then they were cleaned with sandpaper. After that, the candle was lowered into diesel fuel and the moistened soot was scraped off with a paper clip from the surfaces of the insulator, the inside of the housing and between them. Further, the candle was lowered several times in diesel fuel, which was then shaken off from it along with impurities. Sometimes the cleaning procedure with a paper clip and washing are repeated. After that, the candle was wiped dry and was ready for further use.
Incredibly, one tank of the fuel mixture with an unregulated carburetor can be consumed in less than 10 minutes. It was tested in practice when the trimmer was started and operated at high speeds with maximum fuel supply (the adjustment screw was unscrewed much more than normal).