Checking the chainsaw ignition coil with a multimeter

Ignition malfunction

Most often we think about repair after the chainsaw has stopped starting, or there were visual signs of serious damage.

Signs of ignition failure:

  • Chainsaw won’t start, but hesitates (throws up), sneezes and shoots a lot;
  • The power of the chainsaw has noticeably dropped;
  • When sharply pressing the accelerator pedal, there is a lag in the operation of the engine;
  • Chainsaw won’t start when cold, throttles hard until warmed up;
  • Fuel consumption has considerably increased;

If such faults appeared in the work of your chainsaw it is time to carry out diagnostics, regulation and probably also repair of ignition system.

Determining the location of the fault:

First of all, it is necessary to inspect the spark plug, if or on it accumulated a lot of soot, the cause of the malfunction is most likely related to the work of the carburetor, piston group or fuel quality. If visually the spark plug looks serviceable, it’s not plugged and it’s dry. make sure there’s a spark.

  • Unscrew the spark plug, put the ignition cable on it;
  • Using insulated pliers, press the spark plug threads against the motor housing;
  • Pull the starter grip sharply and check for a spark;

If there is no spark, replace the spark plug with a new one and test again. Once you are sure the spark is there, start the engine. But what to do if even a faulty spark plug has no spark? Continue the search:

  • Test the electrical cable for open or insufficient contact with the spark plug. Check the serviceability of the spring in the spark plug cap and check the contact with the armature cable;

To check the functionality of the wiring it is best to use a tester.

checking, chainsaw, ignition, coil

You can set the right gap with a feeler gauge, they are not in short supply and are available for a small fee.

Fault diagnosis with a multimeter

Determine the fault of the ignition coil can also be so-called hardware method. However, for this, you must have a multimeter, with which the diagnosis.

Step-by-step diagnosis of the ignition coil with a multimeter:

  • Set the multimeter to the position where the arrow is at the 200 ohm mark.
  • Study the manual of the chainsaw. Find the optimal resistance for the coil winding installed on our model (most modern chainsaws have a coil winding resistance of 3-5 ohms).);
  • Connect the multimeter to the primary winding of the coil and measure the resistance, if it is normal. continue testing;
  • Connect a multimeter to the secondary winding of the coil, compare the readings obtained with those indicated in the instruction manual;
  • Make a connection of the multimeter to the coil hole, in which the wires are inserted. If the instrument shows normal readings, you can conclude that the coil is in good condition. If the measurement results are far from optimal, you will have to replace the unit (coil) with a new one;

Step by step adjustment of chainsaw ignition:

  • Diagnose the fault;
  • Remove the protective cover;
  • Remove the module with the candle holder and electric cable. Carry out a visual inspection, if necessary replace with a new one;
  • Install the ignition module, but do not tighten the fixing screws as far as they go;

We determine the area on the flywheel with a magnet;

Important: when repairing chainsaw ignition, special attention should be paid to setting the correct gap between the module and the flywheel.

You should also check to see if the flywheel is clinging to the module with the counterweight. If this happens, you may have a failed bearing or a backlash on the shaft.

Disassembling the clutch and oil pump actuator

Before you can disassemble the clutch, you must remove the drive sprocket. To do this, gently remove the lock washer from the grooves on the shaft and remove the sprocket and needle bearing.

It is necessary to unscrew the clutch using a high head (19). It has a left hand thread, so it unscrews towards the guide bar and not the rear of the STIHL 180.

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After unscrewing and removing the clutch, you must immediately remove the deflector plate and the oil pump drive, it’s easy to do, because. к. they are put on the shaft without any fasteners.

Chainsaw ignition. Layout, diagrams, malfunctions.

chain saw ignition system is a complex of components that makes a spark when the engine is started. It is needed to ignite the fuel and bring the engine into a state of proper continuous operation. The main element of the ignition system is the spark plug, which should ignite whenever the engine is in the desired cycle of. And although the system is reliable and well-designed, but sometimes it needs to be repaired, so the user needs to know how his chainsaw is arranged, as well as what he can do to repair its ignition system.

The arrangement of the ignition system of modern chainsaws

Previously, the ignition systems were quite unreliable, but now they have improved. For example, their control system has elements that regulate the pulse depending on what the speed of the saw. Due to this, the engine runs more efficiently, which increases the overall efficiency of the tool. In addition, such elements are important because it is easier to start the saw initially with them.

Equally important is the reliability of modern systems. If previously the ignition used to fail very often, now all of its components are so durable and of such high quality that they need to be repaired very rarely.

So, the modern chainsaw ignition system is a flywheel magneto, spark plug, wire and ignition switch. A distinction is made between contact and non-contact magnetos. The construction of the first one is quite simple: permanent magnets (mounted in the flywheel rim), ignition coil, capacitor and interrupter. The coil contains the core and the primary and secondary windings of the transformer. Another important element. the spark plug. Its construction is as follows: central and side electrodes, insulator, outer casing.

The breaker and the primary winding of the coil are connected in series. The breaker is switched off by the cam on the crankshaft. The primary winding is connected in series not only with the chopper, but also with the trip button. The magneto is mounted in the crankcase on the left side, secured to the base by two studs and nuts.

By means of flywheel magnets, a magnetic field is generated that crosses the coil. This causes a weak current if the contacts in the primary winding are closed. Accordingly, when the contacts are open, there is no magnetic field and an EMF is induced in the secondary winding. Due to this, a high voltage current is generated, which is fed to the spark plug and gives a spark to ignite the fuel. At this point, the piston is almost near the top dead center (4 mm below it).

How to set the ignition on the chainsaw?

Quite often the owners of chainsaws are faced with a problem in which the engine of the tool does not start. One of the main causes of this failure is a malfunction of the ignition system, namely a failure of the factory settings of the unit.

First of all, the owner of the saw will need to unscrew the protective rubber cap and check the plug under it. It is quite possible that it is flooded with oil, which prevents the current flow to the spark plug. In such cases the problem is not in the ignition system, but in the fuel system, namely. in the depressurization of the channels.

However, if the spark plug is completely dry, then you may need to install the ignition on the chainsaw. To do this, unscrew the spark plug and remove the protective cap. After that, you need to measure the gap between the flywheel and the ignition coil. The instructions to each of the chainsaw models indicate the optimum gap between these elements. In most cases it is between 0.2 and 0.4 mm. Since the flywheel of the tool is round, it is not possible to use a car feeler gauge to adjust the gap. It is best to use a special template in the form of a gasket for this purpose. However, it is not easy to find it. Therefore, many experts advise using a cut-out strip from a plastic bottle as a template.

Adjusting the ignition of the chainsaw is quite simple;

  • First, loosen the bolts that fix the elements of the ignition system;
  • Place the plate from the plastic bottle between the coil and the flywheel;
  • Tighten the bolts all the way.
checking, chainsaw, ignition, coil

Ignition Coil Primary & Secondary Resistance Testing

To avoid resorting to frequent adjustment of the ignition system, you should handle the chainsaw as carefully as possible. Try to avoid hitting the tool on wood, especially on the side of the tool where the components of the assembly are located. Especially if your chainsaw is equipped with electronic ignition.

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Algorithm of troubleshooting

In all other cases, the search for ignition faults begins at the end and in order. After each step, check the spark.

  • Replace the old spark plug with a guaranteed working spark plug.
  • If the model has a removable spark plug cover, it is removed and the stripped spark plug wire is shorted to ground with a gap similar to that of a spark plug. Pull the starter. If the spark is there, the problem is in the cap. It is eliminated.
  • Replace spark plug wires where it is possible to remove them from the source.
  • Visually inspect the wires from the switch. In the event of vibration, they could be damaged if they come into contact with metal. If there are friction spots, change the wire, even if there is no external damage to the insulation. You can use a tester or multimeter to check the wire.

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This is the end of small and easily fixable problems. If the problem is not solved, then the cause is more serious. Most chainsaws today have very reliable coils and ignition systems. They are designed to last even longer than the chainsaw as a whole. They have no mechanical moving parts like the old cam systems. They are sufficiently insulated against clogging and moisture.

If by an accidental factory defect intercircuit in the coil happens or the electronics fails, these parts cannot be repaired. Must be replaced with a new one.

There is a mechanical problem that is not uncommon. Due to wear or destruction of the crankshaft bearing, there is backlash on the crankshaft. And then the magnetic rotor starts to get caught in the ignition system housing, inside which it rotates. This is a serious breakdown. It will be necessary to “hollow out” (disassemble) the entire engine, replace the bearing, and reassemble everything in its place.

Checking the ignition coil.

To rule out possible problems with the wiring and turn-off buttons, you may disconnect the control wires from the coil for the duration of the test.

  • Measuring the coil resistance. This method is not always applicable: first, you need to know the characteristics of the resistance of the coil windings. In the 2-nd, the ignition coil in addition to the inductance coil contains the semiconductor elements to form a suitable high-voltage pulse. Therefore, if you try to wire the magneto through the high-voltage and minus wire, you will get either a “Circuit Breaker” indication or a high resistance. If the circuit does check, it is most likely a sign of malfunction.
  • Using a device to check the presence of the spark. It is installed in the circuit break between the spark plugs and the ignition coil high-voltage wire. The device is expensive and is mainly used in the severe service centers.
  • With the help of a spark plug. Unscrew the spark plug and place the barrel on the cylinder. Pull on the starter and watch for a spark between the contacts. This method is approximate and does not give a complete picture of the ignition coil status, because the spark plug is not “under pressure” and the flywheel will spin faster because of the lack of compression in the engine (spark plug turned out)
  • The “barbaric” method. It is used at your own risk in hopeless situations.
  • Remove the cap from the spark plug and put a nail in it. Be careful not to damage the inside of the cap: put it back on the spark plug and operate it. It is better to bite off the head of the nail. Otherwise you may have trouble removing it.
  • Place the nail 6-7mm from the cylinder.
  • “start” the engine, that is, perform the usual actions when starting the tool. How to check the ignition coil check the ignition coil in the trimmer. This will make the ignition system work. Video will help change the ignition on the trimmer, ignition. How to check the coil. Note that the spark plug should be screwed into the spark plug hole.
  • Look for the presence and color of the spark. Ideally, the spark should be “strong” and a bright blue color. Anything else is a sign of malfunction.
  • Important points:

How a chainsaw ignition is designed and how it works Their main faults and troubleshooting

Gasoline saws are necessarily equipped with an ignition system. It is necessary for the timely ignition of the fuel mixture in the engine cylinder. That’s why it’s so necessary to set the ignition on the chainsaw and its periodic adjustment, because without a spark the tool simply won’t start.

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Check the ignition coil on the chainsaw

If the preliminary actions did not help in identifying the cause of the chainsaw malfunction, it is necessary to check the ignition coil of the saw. The diagnosis is performed in several steps:

  • Measure the coil resistance using a multimeter. For this purpose, it is necessary to know the optimum parameters, which are given in the instruction manual. However, because of the use of semiconductor elements in the system, if you try to “wire” the coil, the result will be a “Circuit Breaker” reading. It is normal. A positive test result is an indication of malfunction. Т. е. If the resistance of the coil can be determined with a special tool, then the coil is definitely defective.
  • Check the presence of the spark with a special device. This device should be installed in the gap between the spark plug and the high-voltage lead of the saw’s ignition coil. The reading will be shown on the display. This method of testing is more often used in service centers, since the device required for this purpose is expensive, and the costs will not be comparable to the benefits rendered.
  • Testing the coil with a candle, t. е.perform a homemade ignition. To do this, you need to unscrew it, and then put the body against the cylinder. Now you need to pull the starter and observe the spark. But this method gives only an approximate result, since the flywheel spins faster because of the unnatural position of the spark plug.

Chainsaw Ignition Coil Test Step by Step Easy Test Covers All Chainsaws

If none of these methods are successful or if you need to check in the field, you can proceed as follows:

HOW-TO Fix A Chainsaw With No Spark. Ignition Module Replacement

  • Remove the cap from the spark plug, insert a nail without a cap in the core at a distance of 6-7 mm from the cylinder. Do it as carefully as possible so as not to damage the part.
  • Perform the steps that are required when starting the tool. Now you need to look at the presence of the spark and its color. If there is no malfunction, the spark is strong and the color is bright blue.

This method can be used as a last resort and only if there are no electronic units, and it is important to follow the rules:

  • it is impossible to unscrew the spark plug completely, as it can lead to faster rotation of the flywheel, which is not the correct mode of engine operation;
  • it must be placed at a distance that corresponds to the compression model and the dielectric properties of the fuel mixture, so this parameter can be seen in the manual (the value of 6-7 mm is an average).

Construction of the starter

It is not uncommon for chainsaw manufacturers to equip their units with starters that work on basically the same principle, namely, there is a handle in the groove of the saw body, through which the cord is passed. When the handle is raised sharply, the cord is also pulled, which causes the ratchet drum to engage. This is how the cord reel, which is located on the shaft, is set in motion. At this time, the crankshaft makes several revolutions, leading to compression of the fuel mixture, which at this moment is between the cylinder head and the piston. If the handle is lowered, the ratchet and pins lose their contact and the shaft comes to a stop.

Increasing the power of the chainsaw increases the amount of fuel mixture that must be ignited when starting the chainsaw. In such a case to start the engine it is necessary to increase the number of jerks of the starter cord. To accelerate the return of the drum mechanism, manufacturers use a special steel starter return spring, which has excellent elasticity.

If the spring breaks, it is necessary to: remove the mechanism cage, pull out the spring by fixing the upper part of it with a finger and pulling the starter grip a little to the side. Then, coil a new piece, avoiding kinking and twisting of the new spring element, then carefully fix the cage.

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