Why the lawnmower loses power. STIHL Lawn trimmer does not rev. Checking the fuel mixture
Lawn mower with their own hands is not possible without prior work, knowledge of the theory, understanding the device fuel system. Annotation on carrying out carburetor repair.
Lawn mowers, like all gasoline tools for the garden, is not a difficult technique to maintain. Fixing, tuning without the help of others is possible and necessary. For example, adjusting a lawn mower‘s carburetor with your own hands is a 5 minute affair.
The carburetor from the lawnmower is a node in the power system. In it, as in all carburetors, there is a process of mixing air and fuel (gasoline) for the upcoming supply to the engine cylinders.
In this process, the main thing is the right proportion of fuel and air, and adjust the carburetor.
STIHL Fs 55 Lawnmower Won’t Start Causes
How not to get confused if you don’t get a petrol pump
The tool, despite its small size, is a complex technical device. If you examine the owner’s manual, it turns out that the reasons why the gasoline pump won’t start are known and resolved. You need to consistently rule out factors that make it difficult to start the tool. They usually start with the more accessible units with a simple maintenance check.
All of the reasons for not starting the gasoline pump can be classified according to the specifics of the individual units. In the service center the faults are classified:
- engine malfunction (piston wear, bearing failure, cracked crankcase);
- Fuel mixture malfunction. A clogged air filter pore or carburetor failure;
- the ignition system does not work;
- mechanical failure. Leaky hoses, punctured wires under the braid, burst pipes.
First, the user must check the presence of fuel in the tank. Start according to the instructions by putting the saw on its side. The air damper should be set in the “closed” position, refuel, turn on the ignition and make 3-4 sharp jerks with the starter. If the engine starts, open the air damper. Do not start the gasoline pump. Repeat the operations with the air damper slightly open.
The lawnmower can not run for a long time. and the engine will overheat. Mowing may be no more than 15 = 20 minutes, taking a five minute break. On a hot afternoon, work time is cut in half. When cutting weeds, sedges, shorten the operating time.
If the start-up fails, we start looking for the cause of the failure:
- check the fuel quality;
- to ensure the effectiveness of the spark plug and the cleanliness of the spark plug duct;
- Check that the air filter is clean;
- check that the fuel filter is not blocked;
- check the cleanliness of the breather;
- clean the exhaust port.
complex causes will be found in the diagnosis of failure, leading to a carburetor overhaul. These causes include clogged internal carburetor passages, worn gaskets on the carburetor, and internal hollowness with loss of vacuum. Repairing the gasoline pump yourself if it won’t start will require patience.
Troubleshooting the causes of not getting a gasoline pump
The fuel mixture must be prepared in exact proportions of gasoline and oil. In this case you cannot use another brand of fuel. To prevent dirt, the gasoline should be left in a cup or metal container for 2 days. Do not use plastic containers for storing fuel. Oil is accurately measured with a medical syringe without a needle. Use only freshly made mixture, not leaving spent fuel in the tank. If the engine is unruly, the gasoline stops when you press the gas, it’s probably the faulty fuel.
STIHL FS 55 lawn trimmer does not rev, throttles, rebuild carburettor
LawnmowerNo revs, stalls, rebuild carburetor Thank you for watching
Repair the carburetor on the STIHL FS55 lawnmower
Replacement of the o-ring, gas pedal in the carburetor of the lawnmower
Gasoline does not start when hot. pull the throttle trigger and pull the cord sharply several times until the engine begins to run, then squeeze the trigger. Don’t start. specialized repair.
Check the ignition system, if the gasoline pump does not start, in sequence:
- Remove carbon and dirt from the spark plug, dry it, set the gap of 1 mm;
- connect to a high voltage wire and check the spark by pulling the starter several times;
- If there is no spark, check that the high-voltage wire is intact;
- replace the spark plug;
- Dry the spark plug passage;
- At the same time check the operation of the ignition coil, it is defective if the working plug does not spark.
If the gasoline pump ignition coil fails to start hot, stalls, runs intermittently.
Cleaning or replacing the air and fuel filters will ensure the proper flow of ingredients going into the carburetor. Air filter can be washed in soapy water or replaced. If nylon cloth is used, it is washed, the porous felt filler is replaced. Fuel filter is changed carefully, leaving the intake nozzle open. Does the air filter need to be replaced, can the engine be started with the air cleaner removed. Do I need to change the screen on the fuel supply if the gasoline pump won’t start, a dry spark plug will tell you.
Breather, air vent to gas tank. If it is clogged, a vacuum is created in the tank and the mixture does not enter the carburetor. The hole can be blown with air or cleaned with a needle. The exhaust duct must be cleaned, it is necessary to remove the muffler’s wiping mesh.
Adjustment and adjustment of the carburetor
Maximum and minimum engine speed, regulated by the carburetor. Steady operation of the fuel pump depends on the amount of fuel mixture and air supply and their ratio. The petrol will not start if the carburettor is incorrectly set. The order of the low speed (L), high speed (N) and (T) fuel feeder is adjusted with the same screws:
- The chainsaw must be run for at least 10 minutes, because the adjustment is hot.
- Turn screw H slowly to maximum RPM and then turn 1/4 turn counterclockwise to reduce engine RPM.
- The idle speed is adjusted with the T screw, ensuring that the grasshopper does not rotate.
- The L screw is adjusted by first opening the maximum throttle and then gradually reducing the speed to a steady minimum.
After adjusting a good carburetor with cleaned filters, checked ignition should ensure that the engine runs. If there is a problem with the carburetor after repair, the fuel system should be adjusted again before starting the gasoline pump
Second is the carburetor
Dismantle the unit immediately do not need, especially if the engine stalls after starting or does not hold idle. First try to change the fuel, maybe there is too much oil in it. You can squirt some air cleaner into the air filter, give the engine a little “dry run” at maximum rpm.
Next we go in order. the air filter, fuel filter (it can be outside and in the tank), the fuel pump button, the integrity of hoses. Gas tank cap. the valve might be clogged, the engine just doesn’t pump gasoline. Blow it all out and it will work!
Absolutely. look at the carburetor connection to the intake manifold! If it’s sucking air and not tight. fix it!
Dispensing needle freezes. also a problem with some models. It is enough to push it down or remove it and grind it with velvet.
Why the gasoline grass trimmer does not start
The reasons why the gasoline grass trimmer has stopped starting, can be different, so you need to conduct a step-by-step diagnosis of the machine.
Fuel tank (fuel quality)
Remember, it is always necessary to check the presence and quality of fuel before starting the machine. In this case, do not be greedy and save money, as well as “smart” about the amount of added oil. You need to do everything according to the attached to the unit manual, because if the piston group fails, its replacement will cost about 70% of the total cost of the grass trimmer. Fill up with fuel on the basis that you will use up all of it when you do the work. The gasoline left in the tank loses its properties after some time and can damage the engine. So do not prepare the fuel in large quantities or in bulk. If the lawn trimmer won’t start, try draining the “old” fuel from the tank and fill it with a freshly made mixture.
Important! Filling the apparatus with fuel of unknown origin is fraught with negative consequences. Gasoline should be of good quality, bought at the gas station and its brand should not be lower than АI-95.
The spark plug and spark plug conduit
So, you have changed the fuel, but nothing has changed, and the grass trimmer still does not start. In such a case, it is worth checking the spark plug passage: whether it is not covered with a combustible mixture. Often users put the choke in the “OFF” position when starting the engine and then leave it in the “ON” position, and then the engine stalls. Further, an attempt to restart the engine leads to the fact that the spark plug is flooded with petrol, and starting becomes impossible. To diagnose and correct a possible problem in this assembly, do the following.
- Remove the spark plug, wipe and dry it well. When installing the spark plug in the ICE cylinder, it must be dry.
- Drain the fuel that has accumulated in the combustion chamber. This is done through the hole from which you unscrew the spark plug.
- If there is soot on the electrodes of the plug, it must be removed with either a fine file or a nail file.
- Remember to adjust the gap between the electrodes before re-installing the part. The gap on the spark plug should be 1 mm. You can use a coin as a feeler gauge to check the gap.
- Next, reassemble the unit, read the start-up instructions and try to start the engine again.
If the ICE does not start, you will need to check the spark. To do this:
- unscrew the spark plug;
- put the cap of the high-voltage wire on it;
- touch the metal part of it to the cylinder housing (to ensure contact, you can insert a pipe wrench) as shown in the figure below;
- pull the starter cord so that several revolutions of the engine occur.
Normally, with every swing of the piston, there should be a spark between the electrodes. If there is a spark, then the reason why the ICE does not start, you need to look in other parts of the vehicle.
To better understand how to test the spark plug for spark, you can use this video, where the test is shown on the example of the lawnmower “Union”.
If there is no spark, then first check the cable that connects the spark plug to the coil. perhaps the cause is in it. Use a tester to check it. If you find a broken circuit, you will need to replace the high voltage wire.
Also the ignition coil (magneto) malfunction can be the reason why the spark is gone. The illustration below shows what the coil (magneto) from a Patriot gasoline grass trimmer 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 winding. The primary resistance should be somewhere between 0.4 ohms and 2.0 ohms. If the instrument shows 0, it means that a short circuit has occurred in the winding, and if it is infinite, it is a clear sign of an open circuit. Secondary resistance should be somewhere between 6 to 8 ohms.
On some coils the reading can be as high as 15kΩ.
If your lawnmower does not start or immediately stops after starting, pay attention to the air filter as it may be blocked and this prevents air from getting to the combustion chamber and igniting the fuel. To see if it’s the filter, remove it and try starting the engine. If it works, it means that the cause is found. The filter needs to be replaced or well washed and dried before installation. If you find oil in the air filter, it must be rinsed with gasoline, squeezed well, and dried for at least 2 hours before being reinstalled.
Operating instructions: Safety precautions
The equipment described above must be used, wearing special clothing and using equipment. Clothing must not interfere with work. You should choose one which is close to your body. Avoid wide arms that could catch on bushes, wood or moving machine parts.
It is important to remove your ties and sha. This also applies to jewelry
Before starting the STIHL FS 55 lawnmower you should wear safety boots which have rough soles. It is also important to use a special safety helmet and goggles, which will prevent damage to the eyes.
If you often have to mow the lawn, there are modern appliances available which are specifically designed for this purpose, such as trimmers and lawnmowers. Among other solutions on today’s market are lawnmowers, with the help of which you can maintain the adjacent territory in a well-groomed state.
As one of the important advantages of lawn mowers is that it is not tied to a power source on the principle of electric units. And you can use this equipment even in rough areas and hard-to-reach places, including areas under bushes.
The second one is the carburetor
You do not need to disassemble the unit at once, especially if the engine stalls after starting or does not hold idle. First try to change the fuel, maybe there is too much oil in it. You can inject a cleaner into the air filter, give the engine a little “break” at maximum speed.
Then we go in order. air filter, fuel filter (it can be outside and in the tank), fuel pump button, hose integrity. Gas tank plug. the vent valve may be clogged, the motor simply does not pump gasoline. Blow it out and it will work!
Be sure to look at the connection of the carburetor to the intake manifold! If air is sucked in and there is no leakage. fix it!
Specifics of operation, maintenance
The manual for each STIHL ride-on trimmer explains the machine’s construction, operation and functionality in detail. Strict adherence to the manufacturer’s recommendations greatly extends the life of hand-held mowers.
- STIHL brushcutters use a 50:1 mix of gasoline and STIHL 2-stroke motor oil.
- There are several brands of brand oil, and the STIHL HP Ultra is considered the best. When using non-original engine oil, it is recommended to mix the fuel in a 25:1 ratio.
- The ready-to-use mixture should not be stored for a long time (no longer than 1 month), unlike the original STIHL MotoMix fuel mix, which retains its properties for up to 2 years.
- STIHL grease is used to lubricate the transmission, checking after every 100 hours of operation. The air filter is usually changed annually.
- Sharpen the metal cutting tools as needed, a few filing motions are usually sufficient.
How to use and store the lawn mower
To keep your lawn mower running well in the future, it must be stored and operated in good conditions:
- During operation, carefully monitor the cooling system, carefully and timely clean the channels in the housing, as well as the starter ribs;
- If necessary, use solvents, kerosene or other cleaning agents for cleaning;
- Do not clean the tool “while it is hot”. let it cool down;
- strictly follow the instructions regarding the operation mode, otherwise you can overheat the engine;
- if you do not plan to use the mower in the next month, the fuel mixture should be drained from it, t. к. It breaks up over time into heavy fractions that will definitely clog the carburetor passages;
- After draining the fuel, let the trimmer run at idle until it stops, this will help remove the remaining mixture completely.
Before winter storage, do the following steps:
- completely disassemble the braid, rinse and clean all the parts you can;
- Inspect the parts for damage; if necessary, repair misalignments, rips, bends, and any other malfunctions;
- Pour enough oil into the gearbox and clean the air filter;
- You may partially disassemble the motor, flush, purge, and lubricate all moving parts;
- to grease the piston, you need to unscrew the spark plug, lift the starter piston to its dead center, pour a little oil into the spark plug hole and crank the crankshaft a couple of times;
- If you are not storing the mower indoors, wrap the engine with an oiled rag.
Remember, the careful observance of the rules, will allow you to forget about the bad start of the lawn mower for several seasons.