The situation when a chainsaw Stihl MS 180 stops starting due to lack of fuel supply, is one of the most common problems when using this tool. The owner may encounter the fact that after a long period of parking or intensive work, the engine stalls and no longer starts, although there is a spark and the spark plug is dry. Often the reason lies not in a complex engine breakdown, but in a banal disruption of the circulation of the fuel mixture along the highways.
Understanding the principle of operation of the fuel system allows you to quickly diagnose a malfunction without contacting a service center. In this article we will analyze in detail all the possible reasons why no gas coming in into the combustion chamber, and we will provide a step-by-step algorithm of actions to restore the functionality of your tool.
Ignoring the symptoms of engine starvation can lead to more serious consequences, including failure of the piston group due to running on a lean mixture or attempting to start with a flooded spark plug. Therefore, it is important to promptly identify where exactly the failure occurred and remove the obstacle to the movement of fuel.
Fuel system diagnostics: where to start
The first step in troubleshooting is a visual inspection and checking for fuel in the tank. It may seem obvious, but users often forget that gasoline may have run out or evaporated during long-term storage. If there is fuel in the tank, you need to disconnect the fuel hose from the carburetor and blow through it to make sure that the fluid flows freely.
It is important to check the condition of the fuel filter, which is located inside the tank at the end of the hose. This element prevents debris from entering the carburetor, but over time it can become clogged with tar deposits or small chips. A dirty filter creates high resistance and the chainsaw Calm 180 It simply cannot pump in the required amount of mixture.
It is also worth paying attention to the integrity of the fuel hoses themselves. Over time, the rubber hardens, cracks or swells from the inside, blocking the channel. If the hose has visible damage or has become too stiff, it must be replaced, as air can be sucked in through the cracks, interfering with the operation of the vacuum pump.
- 🔍 Check the fuel level and its freshness (old gasoline loses its properties).
- 💨 Blow out the fuel hose to avoid blockages.
- 🛢️ Inspect the filter mesh for contamination with resin.
- 🔧 Check the tightness of the hose connections to the tank and carburetor.
⚠️ Attention: Never attempt to start the saw with the air filter removed or the carburetor cap open while performing a fuel diagnosis. This can lead to dust being sucked into the cylinder and rapid wear of the piston group.
Problems with the fuel filter and hoses
The most common reason why gasoline is not supplied to the destination, there is critical contamination of the inlet filter. During the sawing process, fine wood dust is formed, which, together with oil vapors, settles on the mesh. A viscous substance is formed that is practically impermeable to liquid.
To replace or clean the filter, you must remove it from the tank through the filler hole using a thin wire or hook. If the filter is made in the form of a simple cylinder with a mesh, you can try to wash it in pure gasoline or acetone, but it is more effective to immediately replace it with a new one. The cost of this consumable is minimal, and its resource is short.
Fuel hoses deserve special attention. In models Stihl MS 180 They are made of oil-resistant rubber, but their service life is limited. Material delamination may occur inside the hose, and the exfoliated particles may block the flow area. Externally, the hose may look intact, but inside it is a solid plug.
When purchasing a new fuel hose, pay attention to its internal cross-section. Using a hose with a smaller diameter will result in a lean mixture and overheating of the engine.
When assembling the unit, it is important to install the hoses correctly. There must be a filter at the end that is in the tank. The second end is connected to the carburetor fitting. An error in the connection (confusion of supply and return, if it is provided for by the design, although in MS 180 the system is often flow-through) will lead to the system not working.
Fuel tank breather malfunctions
One of the hidden, but very common reasons for stopping the fuel supply is a malfunction of the gas tank breather. The breather is a special valve built into the fuel tank cap that equalizes the pressure inside the tank. When fuel is produced, a vacuum is created inside the tank, which must be compensated by the flow of air through the breather.
If the breather valve is clogged with dirt or soured, a vacuum forms inside the tank, which physically prevents the carburetor fuel pump from pumping gasoline. A symptom of this problem is that the saw starts, runs for a few minutes with some fuel left in the carburetor, and then stalls and won't start again.
You can check the condition of the breather by unscrewing the tank cap. If you hear the characteristic sound of air being sucked in (“zilch”), it means there was a vacuum. However, if the problem persists, the cover should be disassembled and washed or replaced. In some cases, it is enough to simply clean the hole in the lid with a thin needle.
| System element | Problem Symptom | Elimination method |
|---|---|---|
| Fuel filter | The saw stalls under load, it is difficult to start | Replacement or washing in gasoline |
| Tank breather | Runs for a few minutes and then stalls, the spark plug is dry | Cleaning the hole or replacing the cover |
| Fuel hose | Complete lack of flow, cracks in the rubber | Replacing the hose with a new one |
| Carburetor (membrane) | Unstable idle, lack of traction | Repair kit or carburetor replacement |
Carburetor diagnostics and repair
If the external elements of the fuel line are working properly, then the problem most likely lies inside the carburetor itself. In chainsaws Calm 180 Diaphragm carburetors are installed, where the fuel supply is regulated by a flexible membrane. Over time, the membrane loses elasticity, hardens or becomes deformed, ceasing to perform its pump functions.
Also, the jets inside the carburetor may become clogged. Even a microscopic speck that gets through an old filter can block the calibrated hole. To eliminate this malfunction, it is necessary to disassemble the unit, wash all parts in an ultrasonic bath or a special solvent, and also blow out the channels with compressed air.
Often, users are faced with the fact that after winter storage, residual volatile fractions of gasoline remain in the carburetor, which turn into sticky resin. This resin permanently glues the valve needle or membrane. In such cases, simple blowing is not enough - a complete overhaul using a repair kit is necessary.
How to properly disassemble a carburetor?
Disassembly should be carried out on a clean surface. Memorize or photograph the position of the levers and springs. When assembling, it is important not to overtighten the cover screws so as not to deform the housing, otherwise the seal will be compromised.
⚠️ Attention: When disassembling the carburetor, use only original repair kits or high-quality analogues. Cheap Chinese membranes often do not meet the required rigidity, which leads to unstable engine operation even immediately after repair.
Influence of fuel mixture quality
The quality of the fuel used plays a critical role in the longevity of the fuel system. For two-stroke engines Stihl it is necessary to use a mixture of high-octane gasoline (AI-92 or AI-95) and special synthetic oil. Violation of mixing proportions can lead to sedimentation, which clogs the channels.
The shelf life of the finished fuel mixture is limited. If you leave diluted gasoline in a canister or saw tank for more than 2-3 weeks, it begins to oxidize. Resins and varnish deposits are formed, which settle on the walls of the tank, hoses and inside the carburetor, gradually narrowing the flow sections.
Using low-quality oil or oil designed for four-stroke engines (which does not burn completely) will also lead to rapid coking of the system. If the saw has been standing for a long time with a full tank, it is better to completely drain the old gasoline and fill it with fresh mixture.
☑️ Checking the fuel system
Prevention and proper preservation
So that the question “why isn’t gasoline flowing” does not take you by surprise in the midst of work, it is important to follow the rules for operating and storing the tool. Regularly replacing the fuel filter (at least once a season) and using high-quality mixture components will significantly extend the life of the carburetor.
If you plan to not use the chainsaw for a long time (for example, in winter), be sure to exhaust all remaining fuel from the tank and carburetor. Start the saw and let it stall on its own. This will prevent the membranes from drying out and the formation of resinous deposits inside the system.
Store the tool in a dry place, away from direct sunlight. Periodically, even during the idle season, it is recommended to crank the engine with the starter (without starting) to distribute the oil over the internal surfaces, although the main emphasis is on draining the fuel system before storage.
The main reason for fuel failure in 80% of cases is a dirty filter or a coked carburetor due to long-term storage of the old mixture.
Why does the Shtil 180 chainsaw start and immediately stall?
Most often, this is a sign that the carburetor is running out of fuel and new fuel is not coming in. The cause may be a clogged tank breather (creating a vacuum), a clogged fuel filter, or a malfunctioning carburetor needle valve.
How often should the fuel filter be changed?
It is recommended to check the condition of the filter every season. If you work in dusty conditions or saw resinous wood, it is better to replace it every 3-4 oil tank fills.
Is it possible to flush the carburetor without disassembling it?
There are special carburetor cleaner aerosols that can be sprayed into the intake port while the engine is running. This helps remove light contaminants, but severe resin coking requires complete disassembly and mechanical cleaning.
What gasoline is best to use for Shtil 180?
The best choice is fresh AI-92 gasoline from large gas stations. The use of AI-95 is allowed, but is not strictly required. The main thing is to avoid fuel with an octane rating below 90 and fuel that has expired.