The situation when a chainsaw Partner Refuses to start after winter inactivity or suddenly stalls in the midst of work, familiar to many owners. Often the problem lies not in engine failure, but in a banal violation of the sequence of actions when starting or contamination of the fuel system. The Swedish brand, assembled in China, has established itself as a reliable tool, but it requires compliance with certain operating rules and quality maintenance.
The first thing to do if the tool is silent is to check the presence of the fuel mixture and the quality of the spark. Unlike more modern models, older series Partner 350 or Partner 351 may be demanding on the condition of the spark plugs and carburetor settings. Ignoring simple checks can lead to you starting to disassemble working components, wasting time and money.
In this article we will look at the main causes of engine failure, starting from the fuel supply system and ending with compression. You will learn to distinguish the symptoms of a “lean” mixture from ignition problems and understand when intervention is really needed. carburetor, and when it is enough to clean the air filter.
Diagnostics of the fuel system and mixture quality
The most common reason why a chainsaw Partner It won't start, it's fuel. Gasoline tends to age, losing its octane numbers and forming tarry deposits that clog the fine passages of the carburetor. If you left the tool in the garage for the summer with a full tank, the likelihood of starting it up is extremely low without prior preparation.
It is necessary to drain the old mixture and fill in a fresh one, observing the proportions of oil and gasoline specified in the instructions (usually 1:40 or 1:50 for modern oils). It is important to use gasoline with an octane rating of at least AI-92, since detonation can quickly damage the piston group. It is also worth checking the fuel filter inside the tank: if it is blackened or stuck together, fuel is simply not flowing to the engine in the required volume.
The condition of the fuel hoses requires special attention. Over time, the rubber hardens and cracks, which leads to air leaks. This disrupts the carburetor, making the mixture too lean to ignite. Check the integrity of the lines from the tank to the pump and carburetor.
Use only special two-stroke oils marked JASO FD or ISO EGC. Motor oils for four-stroke engines or used oils will cause coking of the piston and failure of the tool.
- 🛢️ Check the freshness of gasoline - it should not be stored for more than 2-3 weeks.
- 🔍 Inspect the fuel filter for dirt and darkening.
- 💨 Blow out fuel hoses or replace them if there are cracks.
- ⚙️ Make sure that the tank cap does not create a vacuum (check the breather hole).
Problems with the ignition system and spark plug
If the fuel is OK, the next step is to check sparking. Unscrew the spark plug and inspect it visually. Black deposits indicate an over-enriched mixture or low-quality oil, while a light, almost white deposit indicates the engine is running on a “lean” mixture with overheating.
It is best to check the spark by placing the spark plug on the metal part of the cylinder (ground) and pulling the starter. If there is no spark or it is very weak, replace the spark plug with a new one. For chainsaws Partner candles with a heat rating corresponding to the NGK BPMR7A standard or their analogues are often used. It is important not to overtighten the spark plug when installing, so as not to strip the threads in the aluminum cylinder head.
If there is no spark even with a new spark plug, the problem may lie in the ignition module (coil) or in a broken high-voltage wire. It is also worth checking the gap between the flywheel magnetic circuit and the ignition coil. It should be approximately 0.2-0.3 mm. A gap that is too large will not allow a spark to occur, while a gap that is too small may damage the coil by the flywheel.
How to set the coil gap correctly?
To adjust the gap between the spool and the flywheel, use a business card or a folded piece of paper 0.3 mm thick. Loosen the coil mounting screws, insert a spacer between the magnet and the coil, press the coil to the magnet through the spacer and tighten the screws. Then remove the gasket and rotate the shaft - the clearance should be perfect.
Air filter and air supply
An internal combustion engine works like a pump, drawing in air and fuel. If air access is limited, the proportion of the mixture is disrupted, and the chainsaw Partner stops starting or stalls under load. Clogged with sawdust air filter - a common cause of problems, especially when working in dry weather or when felling trees.
Remove the filter cover and assess its condition. If the filter is made of foam rubber, it can be carefully washed in soapy water, thoroughly dried and soaked in oil (if this is provided for in the design). It is better to replace paper or felt filters, as washing can destroy their structure. Dust that gets inside the cylinder through a damaged filter acts as an abrasive, quickly destroying the resource of the piston group.
Also check the condition of the intake manifold and where the carburetor meets the cylinder. The intake of untreated air through cracks in the pipe or gasket will lead to unstable engine operation. Visually inspect the rubber seals for mechanical damage.
| Symptom | Possible reason | Action |
|---|---|---|
| The candle is wet and black | Over-rich mixture, not enough air | Clean the filter, blow out the cylinder |
| The candle is dry and white | Lean mixture, no fuel | Check fuel filter and channels |
| Candle in oil | Worn rings, too much oil in the mixture | Replace mixture, check compression |
| No spark | Faulty spark plug or coil | Replace the spark plug, check the coil gap |
Carburetor adjustment: three adjustment screws
The carburetor is the heart of the chainsaw, and its correct setting is critical to stable starting and operation. On models Partner There are usually three adjustment screws located: L (Low), H (High) and T (or LA/Idle). Screw L is responsible for the quality of the mixture at low speeds, H - on high, and T adjusts the idle throttle position.
If the chainsaw does not start, a misaligned screw setting is often to blame. L. Try to carefully screw it all the way (without using excessive force!), and then turn it out 1-1.5 turns. This will set the starting position. If the engine picks up but stalls when gas is added, the mixture may be too lean and the screw L you need to turn it out a little.
⚠️ Attention: Never turn the screw
Hwithout a tachometer or experience. Too lean a mixture at high speeds (when the screw is turned too far) leads to piston overheating, scuffing and instant engine failure. The factory setting is usually optimal.
A warm engine is required for fine tuning. Idle screw T achieve stable operation of the chain (it should not rotate in place) and stable speed. When you press the gas sharply, the engine should pick up speed without stalling. If the saw stalls after pressing the gas, add fuel by slightly unscrewing the screw L.
☑️ Basic carburetor settings
Mechanical faults: starter and compression
Sometimes the reason is trivial and lies in the mechanical part. If the starter cord is difficult to pull out or sticks, the problem may be a broken starter spring or a jammed ratchet. Disassemble the starter housing, check the integrity of the spring and lubricate the mechanism. A broken cord can also prevent starting by getting stuck inside the case.
The bigger problem is loss. compression. If you do not feel any characteristic resistance when you pull the starter, it means that gases are breaking through the rings or valves (in two-stroke engines through the windows). You can check the compression with a compression gauge: the normal value for chainsaws is 8-12 atmospheres. A value below 6 atmospheres indicates critical wear of the piston group.
It is also worth checking the condition of the crankshaft seals. When they wear out, air leaks into the crankcase, which disrupts the process of preparing the fuel mixture. An indirect sign of oil seal failure may be oil or fuel leakage at the shaft exit point, as well as a whistling sound during operation.
Lack of compression is the most expensive diagnosis. In 90% of cases, this requires replacing the piston group and seals, which is economically feasible only for powerful professional saws.
Seasonal storage and preparation for work
To prevent the question “why the chainsaw won’t start” from arising every summer, it is important to properly preserve the tool. Before long-term storage (more than 2-3 weeks), use all fuel from the tank or drain it completely. The remaining gasoline evaporates, leaving resins that tightly seal the carburetor jets.
After draining the fuel, start the engine and let it run until it stops. This is guaranteed to remove any remaining mixture from the carburetor. Store the saw in a dry place by removing the chain and bar, cleaning them of sawdust and lubricating them with special oil. Regular maintenance takes 10 minutes, but saves you hours of repairs.
If the saw still does not start after storage, try pouring 2-3 ml of clean mixture directly into the spark plug hole, tighten the spark plug and make a few jerks with the starter. This will create the necessary vapor concentration for the first flash. If this does not help, you will probably need to completely disassemble and ultrasonic clean the carburetor.
What to do if the chainsaw starts and immediately stalls?
Most likely, the fuel filter in the tank is clogged or the ventilation of the tank cap (breather) is broken. Try opening the tank cap slightly during startup. If the saw starts working, clean or change the cover and filter. Also check the condition of the muffler: carbon deposits in the exhaust duct can choke the engine.
Is it possible to run a Partner chainsaw without an air filter?
Short-term - yes, for diagnostics. But prolonged operation without a filter will lead to abrasive dust entering the cylinder, which will cause scuffing on the piston and loss of compression. Never saw without a filter installed.
What gasoline is best to use for Partner 350/351?
It is optimal to use AI-92 gasoline from proven gas stations. AI-95 may have a higher octane number, but often contains more alcohols, which is harmful to the rubber carburetor membranes of older saws. The main thing is the freshness of the fuel.