An overheated engine often does not start hot because the fuel in the carburetor boils, creating gas plugs that block the normal supply of the mixture. Long-term work under load leads to the fact that the temperature of the case of the saw headset and the cylinder-piston group exceeds the calculated norms, causing a violation of gasoline evaporation. As a result, the piston gets too rich or too poor mixture, which makes ignition impossible even with a proper ignition system.
To fix the problem, you must immediately stop the launch attempts and let the tool cool for 10-15 minutes by removing the air filter. If after cooling, the chainsaw starts from the first time, but stalls when opening the throttle, the problem lies in the settings of the carburetor or the tightness of the fuel system. Ignoring this symptom can cause serious damage. piston-group Or a cranking of the crankshaft bearings.
Problems with the carburetor and fuel overflow
The most common reason why chainsaw ceases to start in a heated state, is a banal overflow of fuel. When the engine is hot, the gasoline in the float chamber begins to evaporate intensively, increasing the pressure and pushing the excess fuel into the cylinder. The spark plug instantly becomes wet, the spark slips through, but ignition does not occur, since liquid gasoline does not burn.
To eliminate the overflow, you need to turn the candle and dry the cylinder, making several blank scrolls with an open throttle. If the candle is constantly thrown, adjustment is required. carburettorIn particular, check the level of fuel in the float chamber and the condition of the shut-off needle. Incorrect adjustment of the screws of quality and quantity of the mixture can also lead to re-enrichment of the mixture at high revs.
How to properly dry the cylinder
Unscrew the candle, close the candle hole with clean rags and several times sharply pull the starter. Then wipe the candle dry and insert it back in.
Warning: Do not try to start a flooded chainsaw with a closed air valve - this will only worsen the situation and completely flood the combustion chamber.
Failures in the ignition and candle system
The ignition system often fails under the influence of high temperatures, when the coil or ignition module loses its properties. The spark gap on the candle can be broken, and the soak on the electrodes when heated begins to conduct current, causing a breakdown on the mass instead of a spark. Visual examination spark-plug may show black loam, oily deposits or melting of the central electrode.
If the spark disappears on the hot one, this is a sure sign of a breakdown of the high-voltage wire or a malfunction of the ignition coil. In such cases, a spark may appear, but it is too weak to ignite the fuel-air mixture in conditions of high cylinder temperature. Replacing a candle with a new one with the correct potassium number often solves the problem if the ignition module is serviceable.
Check for a spark by attaching a candle to the metal of the case. If the spark is blue and ringing – the system is fine, if red or missing – replacement elements are required.
Violation of tightness and air sucking
Suction of foreign air into the intake manifold is an insidious malfunction that manifests itself precisely when the chainsaw is hot. When heated, the rubber glands of the crankshaft and gaskets expand, and when cooled, they shrink, which can temporarily eliminate or, conversely, increase the leakiness of the joints. Excess air impoverishes the mixture, making it non-flammable, which leads to the inability to start the engine.
For diagnosis, it is necessary to carefully examine the space around the carburetor, intake manifold and crankshaft glands. Often cracks in the fuel hoses or a loose fit of the carburetor to the cylinder cause unstable work. Use of the carburettor will help to identify the place of the sucker: if the engine speeds change when sprayed on the joints, then the tightness is broken.
- 🔍 Check the condition of the gasket between the carburetor and the cylinder for burnouts.
- 🔍 Examine the crankshaft oil for cracks and traces of oil.
- 🔍 Make sure the integrity of the fuel hoses and the density of their landing on the connections.
Impact of Fuel Mixture Quality and Filters
The quality of gasoline and oil directly affects the ability of the engine to start in a warmed-up state. The old fuel mixture, which has stood for more than two weeks, loses its octane properties and is prone to the formation of resinous deposits that clog the jelly. In addition, the use of oil with the wrong octane number or the wrong proportion of mixing leads to detonation and overheating.
A clogged fuel filter or air filter can also create flow resistance that becomes critical when the engine needs more power to overcome compression. If the filter is airborne, the mixture becomes too rich, which, when combined with a hot engine, gives the effect of "choking".
| Component | Symptoms of pollution | Decision |
|---|---|---|
| Air filter | Black smoke, power loss | Purge or substitution |
| Fuel filter | Engine stalls under load | Replacement of the filter |
| Carburettor grid | Unstable turnovers | Ultrasound washing |
| Silencer | Overheating, difficult launch | Cleaning up the scoop |
Checking compression and CNG condition
Low compression is the physical inability to create enough pressure to ignite the mixture, which is especially noticeable on a hot engine. Wearing piston-ring, a bully on the cylinder or the production of crankshaft bearings leads to the fact that the mixture is simply blown back into the crankcase or muffler instead of compression. Measuring compression with a compressometer will give an accurate answer: if the value is below 8 atmospheres, starting will be extremely difficult.
Often the cause of the compression drop is overheating, which led to thermal expansion of the piston and bullies. In this case, the chainsaw may stall immediately after launch or not start at all, emitting a characteristic whistling sound when scrolling with the starter. Repair in this case requires disassembly of the engine and replacement of the piston group.
☑️ Diagnosis of compression
Failures of the tank sapuna and fuel system
A fuel tank sapoon is a small valve that is often ignored, although it is critical to the operation of a chainsaw. Its task is to equalize the pressure in the tank: if it is clogged, when fuel is produced inside the tank, a vacuum is created that prevents gasoline from entering the carburetor. On the hot, when the fuel expands and evaporates, the pressure in the tank can, on the contrary, become excessive, disrupting the valves.
Checking the sapoon is easy: you just need to open the lid of the tank after the saw has stalled. If there was a characteristic sound of the intake air and the engine started after that, then the problem is in the ventilation of the tank. Cleaning the sapuna with a needle or replacing it completely eliminates the problem.
⚠️ Warning: Operating a chainsaw with a faulty sapuna can cause the fuel tank to deform or the fuel hoses to rupture due to a pressure drop.
Algorithm of actions in case of engine overheating
If your chainsaw is not hot, it is important to act consistently so as not to aggravate the breakdown. The first step should always be to stop launching attempts and visually inspect the tool for fuel leaks or damage. Allow the engine to cool naturally without watering it, as a sharp temperature drop can lead to cracks in the cylinder.
After cooling, try to start the saw according to the standard procedure: open the air valve, turn on the decompressor (if any), pull the starter. If the launch was successful, let the tool work at idle speeds, listening to the sound of the exhaust. Extraneous noise or a change in the color of the exhaust will indicate the need for a deeper diagnosis.
The main rule: if the saw is not started on the hot one, but starts on the cold one - the problem is in setting up the carburetor, ignition system or fuel system, and not in the mechanical part of the engine.
Prevention of Startup Problems
Regular maintenance is the only way to avoid situations where a chainsaw fails at the most inopportune moment. Timely replacement of candles, cleaning of air filter and use of fresh fuel mixture prolong life of the tool. It is also important to monitor the tension of the chain and lubrication of the tire, as increased friction causes the engine to work with overload and overheat.
Store the tool in a dry place and drain the fuel if you don’t plan to use the saw for a month. Old gasoline is converted into a viscous substance that clogs the carburetor channels and leads to expensive repairs. Compliance with these simple rules will ensure a confident start in all conditions.
Why does the chainsaw start and immediately die on the hot one?
This is a classic sign of improper tuning of the carburetor (too poor mixture on idlers) or air sucking. It is also possible clogging of the fuel filter or malfunction of the tank sapuna.
Can I add oil to the gasoline for the chainsaw on the eye?
Absolutely not. The proportion should be accurate (usually 1:25 or 1:40 depending on the model). Excess oil will lead to the soot and coking of the piston, and the lack - to bullies and wedges of the engine.
How often should I change the spark plug in the chainsaw?
The candle’s life depends on fuel quality and operating mode, but on average, it is recommended to replace every 100 hours or as unstable sparks appear.
What if the chainsaw does not start after winter?
Most likely, the carburetor left the old mixture. It is necessary to drain the residues of fuel, blow out the system, replace the candle and pour fresh gasoline with oil.