Chainsaw Poor Starts And Stalls

Using a chainsaw facilitates hard work. But sometimes the chainsaw starts and stalls, the reason for this can be any. What to do? You have to choose: take it to the workshop to specialists or try to repair it on your own. We will try to help the reader understand the causes of failure, ways to eliminate breakdowns and give tips on operating chainsaws. In turn, it will be useful for the owner to familiarize themselves with the factory operating instructions and design features of their chainsaw. This information will help him correctly use and professionally perform tool repairs.

Chainsaw Poor Starts And Stalls

Chainsaw device diagram.

Characteristics of the internal combustion engine of chainsaws

The main malfunctions of chainsaws are associated with engine failures. Domestic and foreign manufacturers use single-cylinder two-stroke internal combustion engines as a chain drive. The motor design is simple. The ignition is normal, without the installation of capricious electronics. Chainsaw engines operate reliably in various climatic conditions. Fuel for the carburetor engine is obtained by mixing AI-92 gasoline and special oil. Since the oil pump is not provided in the design, the piston and cylinder are lubricated with a mixture of gasoline and oil. The saw engine develops power from 2 to 5 kW, and the crankshaft rotational speed reaches 14,000 rpm. At such high speeds and load requirements for oil are special. Use the oil specified in the instructions. When changing the oil to the usual motor resource of the tool is sharply reduced. Remember that filling the tank with gasoline without adding oil is strictly prohibited.

Tools and materials

Scheme of a two-stroke engine of a chainsaw.

The design of the mechanical components of chainsaws is characterized by good reliability and maintainability. Almost all units and parts have free access. With the necessary equipment, they are easily removed for repair or replacement. To disassemble and verify the life support systems of the chainsaw engine, stock up on the following tools and materials:

  • A set of fitting and assembly tools;
  • Candle end wrench;
  • Tester;
  • Pressure gauge for measuring compression;
  • Probes for measuring gaps;
  • Needle;
  • Sandpaper;
  • Fuel mixture (gasoline oil);
  • Rags.
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Motor Fault Classification

Before starting the chainsaw, it is necessary to check the condition of the saw part, refuel the fuel and oil tanks. After checking, start the launch. If there are deviations or malfunctions in the drive, it is necessary to carefully inspect the saw motor. As a result of external inspection, make sure that all components are complete and complete, that there are no mechanical damage, gasoline and oil leaks. We point out the main malfunctions associated with poor engine performance:

Chainsaw fuel system.

  1. The engine will not start.
  2. Starts up, but soon the chainsaw stalls.
  3. It is unstable.
  4. It ceases to function under load.
  5. Loses its power.

Engine troubleshooting is conducted in the following main areas:

  • Failure of the ignition system;
  • Failures in the fuel supply system;
  • Malfunction of the piston group.

Saw mechanisms need constant care, maintenance and repair.

Knowing the operating principle of a two-stroke gasoline engine will help the operator to independently determine the cause of the failure and quickly restore the operation of the chainsaw.

In-house troubleshooting

If it is impossible to start the engine, it is necessary, following the sequence, to perform the following actions:

Location of the air filter and spark plug.

  1. Check for gas in the tank.
  2. Replace fuel if it has been stored for more than a month.
  3. Check fuel filter. Disconnect the hose from the carburetor and observe the trickle. If gasoline flows freely, the fuel filter is not clogged. If not enough, clean the hole in the tank cap or filter.
  4. Clean the air filter. The air filter can be removed for a test run.
  5. Inspect and clean the muffler from burning.
  6. Check the operability of the launching device. If necessary, repair the starter (replace the pulley, spring or cable).
  7. Disassemble and clean the clogged carburetor.
  8. Ring the high voltage wire with a tester for a break.
  9. Measure the clearance between the flywheel magnets and the ignition module (should be 0.2 mm).
  10. Unscrew the candle and inspect it. Measure the gap between the electrodes with the probe (normally 0.5-0.6 mm). By the appearance of the electrodes, we determine the nature of the malfunction. If the spark plug is dry, there is no intake of the working mixture. A gas-filled working part indicates poor carburetor adjustment or the absence of a spark. To check for a spark, connect the high-voltage tip to the spark plug, put the skirt on the radiator of the cylinder, and pull the starter cord. If there is no discharge between the electrodes, replace the spark plug. The formation of carbon deposits on the electrodes indicates a poor quality of the fuel mixture. Sand the center and side electrodes.
  11. No compression. The reason is the failure of the piston group. Measure compression. First you need to unscrew the candle. Then insert the pressure gauge into the cylinder bore and move the piston with the starter cord. By the magnitude of the pressure in the cylinder, the state of the cylinder-piston group (CPG) is judged. It must be at least 8 atm. Low rates are caused by wear of the cylinder, piston, piston rings.
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What to do if the engine stalls after starting?

Scheme of the interaction of fuel and air flow in the carburetor of a chainsaw.

Often we observe a short operation of the saw after start-up. The chainsaw stalls almost immediately. This malfunction has characteristic features. The list indicates the probable causes of the malfunction and ways to resolve it:

  1. Lack or small volume of fuel. If a failure occurs during sawing in an inclined position, this indicates a rise in the intake pipe above the fuel level. Check for fuel in the tank. Pour gasoline to the required level.
  2. Poor fuel mixture. Prepare fuel in strict accordance with the instructions of the saw manufacturer. Replace the mixture completely.
  3. The breather is clogged. Low fuel consumption to the engine. Breather. Breathing hole in the tank cap. Clean the blockage with a needle.
  4. Poor contact of the plug with the cap of the high voltage wire. In this case, the porcelain candle insulator is very hot. Strip the contact and push the cradle tightly onto the spark plug.
  5. Faulty spark plug. Replace with a new or obviously working one.
  6. Muffler clogged by combustion products (exhaust gas). The silencer must be cleaned.
  7. The carburetor is not adjusted. To adjust the quality of the mixture, the carburetor has 3 screws: “L”. Fine tuning, “H”. Coarse high-speed tuning and “T”. Idling adjustment. Following the sequence of adjustment of the screws, we achieve higher crankshaft revolutions.
  8. Air filter clogged. The air enters the carburetor in a small amount. We get an enriched mixture. The saw stalls with an increase in load when sawing hardwood and large-diameter trunks. Rinse the filter in warm water and dry.
  9. Failure of the piston group. Replace defective parts.
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Now you can independently find and eliminate the reasons due to which the chainsaws start up and stall, the reasons for their stopping. Recall that a chainsaw develops a high speed of movement of the working body (chain) and is considered a dangerous cutting tool. Strictly observe safety rules when performing work, maintenance and repair of the chainsaw.