How To Check A Spark On A Chainsaw Candle

Chainsaw ignition Chainsaw ignition system. This is a whole complex of elements with the help of which a spark appears when starting the engine. It is needed in order to ignite the fuel

How the ignition of a chainsaw works. High voltage wire

Next, check the spark plug wires. They can often run in such a way that many bends are observed. In those places, the wire can be damaged, while it looks perfect. Next, inspect the spark plug cap of the ignition wire. There should be no brown coating on it. If there is one, this means that the spark is not firing in the right place, but in all parts around the ceramic insulator. The cap can also be damaged, cracks, chips. The check must be carried out carefully, because due to the damaged insulating layer, you can get an electric shock.

Spark plug

Most often, breakdown occurs due to the spark plug. It is worth checking if the insulator is damaged and the electrode is not worn out. Check the entire candle for integrity and the absence of defects, this is the integrity of the wires from the coil, and the presence of insulating material, etc.

On / off button

A frequent breakdown of the ignition system is a malfunction of the shutdown switch. To check it, the wires are disconnected from the module and the operation of the saw is checked. If there is a spark, it’s the switch.

Chainsaw ignition module (coil) problems

Husqvarna chainsaw ignition coil

The switch and the ignition module that regulates its operation can often fail. The coil may also be faulty. If all elements of the ignition system are in good working order, but there is no spark, suspect the module and the coil. And the problem of a malfunction of these elements is that it is impossible to repair the module or to fix part of the coil, they need to be replaced. Of course, if possible, it is better to put the module from some old saw and see if this is the case. After all, you can simply make a mistake at some stage and suspect what actually works.

Do not trust all kinds of testers, they often show false information about the health of the ignition system. Only diagnostics with a different module or coil will be valid.

If the electronic module is bad, there is such a symptom: as soon as the chainsaw heats up, a very weak spark is emitted. Also, after refueling, the unit may not start. This is due to the fact that the coil or module is very hot, their resistance increases, so the spark weakens.

If there are breakdowns in the ignition system, and there is no experience in repairing them, you should not try to repair everything yourself. Elementary things, such as checking the integrity of a candle or wires, can be carried out at home, but more complex diagnostics, and even more so, the replacement of units should be carried out by professionals. And then you can be sure of the quality of the work performed.

Chainsaw won’t start, no fuel supply

This is a fairly common problem for cheap gasoline saws not equipped with a hand pump. Once I was unable to start the chain saw after a long period of inactivity in the usual way. But don’t be discouraged, it is quite easy to defeat this problem.

To do this, remove the air filter cover, take out the filter element and pour a few drops of gasoline directly into the carburetor with a small syringe. We wait half a minute until vapors form and pull the starter handle.

How to start a chainsaw

In the midst of harvesting firewood, it would be very annoying to be left with an inoperative tool, so it is important to know how to start the chainsaw, how to do it correctly and what to do if the saw does not start. Let’s talk about this in more detail.

The chain saw is a rather complex device and therefore requires correct operation and competent maintenance for trouble-free operation.

A reliable start of the saw requires, first of all, a working spark plug, a reliable fuel supply and a properly prepared fuel mixture for two-stroke engines. By the way, it should be noted that after a long downtime of the saw, it can be difficult to start it the first time, and here you are very lucky if the saw is equipped with a manual fuel pump, otherwise you may need to tinker a little.

How To Check A Spark On A Chainsaw Candle

How to start a chainsaw correctly

Let’s consider the general points. Although all chainsaws are similar to each other, there are still differences when starting. Therefore, in any case, read the instructions first. For example, in some models of Husqvarna petrol saws, the instruction requires the chain to be locked with the emergency brake before starting. In some chainsaws of other brands, the opposite is said to avoid difficult starting.

And so, you pulled the starter handle several times, but the saw did not show the slightest signs of life (if there were seizures, then you can wait a couple of minutes in order to let the fuel cloud form inside the cylinder and try to start the chainsaw again and the chances of success in in this case, not bad), then do not force her, but first do this:

What to do if the chainsaw won’t start

Remove the spark plug and inspect it. It should be light brown and free of black patches. In addition, it should not be completely dry. This may indicate that there is no fuel supply. If it is very wet, then this indicates that you flooded it.

In this case, simply dry the candle for a while, and blow the cylinder several times by pulling the starter handle. Screw the spark plug back in and try starting the chainsaw again.

How to check the spark on a chainsaw candle

Although much less often, it also happens that it is impossible to start a chainsaw due to the lack of a spark on the spark plug electrodes. How can you check for its presence? It’s very simple. Again, we turn out the candle, put a high-voltage wire on it and ensure reliable contact of the spark plug body (that is, its skirt, where the thread is) with the cylinder block. After that, we pull the starter hand as when starting.

You should clearly see the spark. If there is a fuel supply, but there is no spark, then most likely the magneto is faulty or there is a broken wire somewhere in the system. In this case, check the integrity of the magneto and the continuity of the electrical circuit. After all these operations, the engine should start. If not, then write in the comments. Let’s try to figure it out.

Better verification methods

To get a more accurate reading, it is recommended to test the spark plugs under pressure. And first of all, on the ICE itself.

Here’s how it’s done:

  • In idle mode, armored wires are disconnected from each candle in turn;
  • The operation of the motor is diagnosed by ear.

Determine a faulty plug based on the following rule. The candle that, after removing the wire from it, least of all affects the functionality of the motor, and is inoperative.

In other words, if you remove the armored wire from the candle, then this should automatically affect the operation of the power unit. If the internal combustion engine shows little or no reaction at all, then it (the candle) does not work.

This test method is considered more advanced, since it excludes the possibility of an electric shock and is carried out under pressure, that is, just in the operating mode. However, again, this verification option can be called not ideal and not 100% due to the tripling of other engine components. It is obvious that a broken armored wire, a faulty ignition module, etc. Can become the culprit for the unstable operation of the engine, which confuses the accuracy of the readings.

The second way to test a spark under pressure is to use a pressure chamber. This is a special test bench that effectively tests candles at the required pressure. Such equipment is available in professional service stations, but if you try, you can get it in your own garage.

There is another possibility to provide pressure in the garage, if you use a syringe. In fact, he is also capable of creating pressure.

The third method of checking the spark is much simpler than the others. It is enough to replace the candle on which the doubt falls and put a new one. This will make it easy to identify the failed part, because after the motor starts to function differently, it is better, this will directly indicate a malfunction of the old plug.

Simple ways to check

So, the first and most common check option is the old-fashioned one. Here’s what to do:

  • Stop the car;
  • Turn off the engine;
  • Remove the test plug;
  • Put an armored wire on top of it, and put the base of the candle on the ground (any part of the body or on the surface of the block);
  • Then crank the starter motor checking for spark.

Another easy way to check a candle is to use a handy tool. For example, such as a piezo probe or a gas lighter element. It is disassembled, the piezoelectric element is removed from the inside, which is responsible for sparking (the silicon system of a modern lighter).

  • The wires from the piezo probe are connected: one to the top of the candle, the other to the bottom;
  • Now you need to press the probe button, if the spark flies through, then the candle is serviceable, and if not, then it is broken.

Another, no less common method of checking, guarantees a more accurate result. Instead of an improvised device, a real multimeter is used.

Here’s how it’s done:

  • The multimeter is set to 20 kOhm;
  • The voltage of the main electrode is tested;
  • Resistance is shown if there is contact between the core electrode and the tip.

It is noteworthy that each type of candlestick has its own resistance indicator. However, even this method of verification is not able to provide an accurate and 100% result. The fact is that if the spark on the candle is bad, then it may not be highlighted when checking. This is due to open air in this case, the current for sparking is required much less than in the operating mode, when the spark jumps only with a well-compressed fuel assembly.

How to Test a Spark Plug in Several Ways

Not sure how to test a spark plug on your own? This is easy to do even in the field, it is enough to be able to unscrew the candles and test for a spark. There are many other verification methods, all of which are detailed below.

Spark plugs and engine

It is noteworthy that the condition of the engine can be determined by the appearance of the spark plugs. Experienced motorists can easily identify engine problems by examining the color of spark plugs.

Attention. If you decide to check the state of the internal combustion engine by burning candles, you should know that this is done exclusively on a warm engine, otherwise the readings obtained will be erroneous.

So, carbon deposits on candles may indicate problems such as increased fuel consumption, the presence of an excessive amount of metal additives, poor fuel assemblies, prolonged engine downtime, the development or occurrence of oil scraper rings, etc.

For more information on the types of carbon deposits and their meaning, see the table below.

Gray-light brown carbon deposits Good carbon deposits, the engine is fine
Candle with carbon deposits similar to limestone These are non-combustible engine oil additives. Consequently, the same deposits accumulate on the valves and on the piston crowns. They significantly impair heat dissipation, and abundant deposits on the valve disc and stem can worsen the filling of the engine cylinders. Such carbon deposits cannot be burned out; they are only cleaned mechanically. To avoid this type of carbon deposits, always use good quality engine oil.
Candle with black velvety carbon This is a consequence of the over-rich mixture. In this case, carbon dioxide can go off scale for 10 percent. The reason for this soot. Incorrect adjustment of the ignition system or power supply. Usually, along with the appearance of carbon deposits, the car has an increased fuel consumption. After eliminating these malfunctions, carbon deposits disappear automatically when the car is operated at high revs (revs must be above 4000 rpm)
Resinous carbon candle This type of carbon is similar in appearance to tar. This is a sign of a broken, defective spark plug (cold plug). The problem is solved by replacing the plug with a new one, or when the reason was in the armored wires or the plug does not fit the engine. At worst, when a spark appears on it due to poor compression in the cylinder (the gas distribution mechanism is faulty: valve crack, bent valve, pusher breakage, etc.). In any case, the problem cylinder will not produce the required power, the engine “troit”, and in the cylinder itself the mirror is worn out. Unburned gasoline dilutes the lubricant.
Candle with a light carbon deposit with the smallest droplets of metal near the central electrode Indicates candle overheating (hot candle). There are several reasons for such a malfunction: the spark plug may not fit the engine, the ignition may be too late, problems with engine cooling, etc. Because of this, the pistons burn out, the valves crack, a piece breaks off the spark plug insulator and gets between the piston and the cylinder.

On how to test the spark

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Dismantling and cleaning the muffler

If the engine works fine at low speeds, and at high speeds it starts to stall, the reason may lie in the muffler spark arrester, clogged with combustion products.

  • Remove the muffler;
  • Disassemble (there are also non-separable models);
  • Clean from carbon deposits using detergents;
  • Dry with a hairdryer;
  • Refit.

Dry cleaning is unacceptable, as the soot contains carcinogens, the inhalation of which is dangerous to health. After removing the muffler, close the outlet with a clean cloth.

Interruptions in the operation of the chainsaw signal a possible clogging of the muffler

To prevent the muffler from clogging, it is necessary to monitor the composition of the fuel mixture. The amount of oil should not exceed the rates recommended by the manufacturer. Poor oil quality also negatively affects engine performance.

Repairing the chain lubrication system

Consider three main faults:

  • Oil leakage. Check that the pipes are tightly connected to the pump unions and if they are cracked. Problem tubes are sealed or replaced.
  • Insufficient oil supply. Most likely the lubrication passages are clogged.
  • Cracks in the oil pump housing. Part replacement required.

Fuel supply system repair

Fuel may not enter the cylinder for the following reasons:

  • Dirty fuel filter. Remove the fuel hose and check how the fuel flows. If the jet is weak, the filter may need to be cleaned. It is taken out through the filler hole of the fuel tank and cleaned; in case of severe contamination, it is replaced with a new one. As a preventive measure, it is recommended to replace the fuel filter every three months.
  • Clogged breather (holes in the fuel tank cap). Check also by disconnecting the hose, in case of blockage, clean it with a needle.
  • Lack or insufficient amount of fuel. There may be several reasons for the malfunction. The first reason is the clogged air filter. Air ceases to flow into the carburetor in the required amount, in this regard, due to a too rich fuel mixture, the engine’s operation is disrupted. The contaminated filter is carefully removed, cleaned and rinsed in water, then dried and reinstalled.

Another reason is the improper adjustment of the carburetor. The adjustment is made with three screws.

Timely replacement of the fuel filter ensures full fuel supply

The fuel hose and choke actuator must fit snugly against the fittings

The throttle cable must be in place

During work, you must use the instructions, otherwise you can only make it worse.

And the last reason is a violation of the integrity of the membrane or clogging of the carburetor channels.

To repair the carburetor yourself, you need to get acquainted with all its parts.

All parts must be clean, dry and in good condition.

Constructive components of the chainsaw

All chainsaws are similar in structure, regardless of whether they are European (ECHO, Stihl, Husqvarna) or domestic (Kedr, Ural). Inside the body are the main elements of the fuel tank and engine, and outside the starter, handle, saw part (tire) with a chain. A sharp jerk of the cable starts the engine, and that saw blade.

To begin with, we suggest that you familiarize yourself with the rollers, which show how the chainsaw works and how it works:

From time to time, the saw malfunctions, which require disassembly to eliminate. What can happen to such a simple mechanism as a chainsaw? At least the following:

  • Ceases to start;
  • Starts up, but soon stops;
  • Ceases to function in the cut;
  • Loses its power;

Most of the malfunctions are associated either with interruptions in the operation of the engine (fuel supply system, exhaust system, ignition, cylinder-piston part), or with malfunctions of other systems and components (clutch, chain brake, tire, lubrication system). Consider the most common breakdowns and techniques for their elimination.

A working chainsaw starts with one jerk and does not fail in the cut

Checking the ignition system

The first thing to do if the chainsaw breaks down is to inspect the spark plug by disconnecting the wire and carefully unscrewing it with a special key.

Chainsaw ignition system components: 1 flywheel with magnets, 2 ignition module, 3 spark plug, 4 high voltage wire

Unscrew the spark plug to check its condition.

Her appearance says a lot:

  • Dry. Most likely, the fuel mixture does not enter the cylinder. It’s not about the ignition system, so the plug is screwed back in.
  • Strongly splashed with fuel. The reason for the excess fuel mixture lies either in the violation of the starting rules, or in the incorrect adjustment of the carburetor. The spark plug is carefully wiped, shut off the fuel supply and turn on the starter to remove excess fuel and ventilate the combustion chamber. Then the candle is put in place and the mechanism is started again.
  • Covered with black carbon. This may indicate the use of low-quality oil, an incorrectly adjusted carburetor, or an incorrectly calculated gasoline to oil ratio. The candle should be washed, cleaned of carbon deposits with a sharp object (awl or needle), wipe the electrodes with a sandpaper and put in place.

When checking the candle, you need to pay attention to the gap between the electrodes: it is considered normal from 0.5 to 0.65 mm. A damaged or worn gasket must be replaced.

A large amount of black carbon on the spark plug indicates a malfunction of the engine.

To be sure, you should also check for a spark. To do this, put the ignition cable on the spark plug, connect the plug nut and the cylinder with pliers, start the starter and watch for the spark. If it is missing, the plug must be replaced. If the new spark plug also does not produce a spark, the problem is in the high-voltage wire or in a broken connection with the spark plug.

Assessment of the state of the cylinder-piston group

Often the engine will not start or run at full strength due to low cylinder pressure. It can be caused by piston or cylinder wear, piston ring sinking, bearing wear. You can partially examine the condition of the cylinder-piston group (CPG) by removing the muffler and looking into the opened hole.

A compressor placed in the spark plug hole will help to measure the compression in the engine, according to the measurement results, you can also talk about the state of the CPG. Accurate data is obtained only after the complete disassembly of the mechanism. If the piston is chipped or scratched, it must be replaced. The piston ring must be clean, free of carbon deposits, and be exactly in place.

Piston and crank mechanism wear is considered a serious problem.

According to the results of measuring the compression, one can judge the condition of the parts of the CPG