The Spark On The Trimmer Disappeared

Ignition coil

If the candle is replaced with a new one, but the scooter (moped) does not start anyway, we diagnose the coil. The coil is a device with two primary and secondary windings. Visually, this is a barrel with two contacts and an outgoing high-voltage wire.

The role of the coil is to increase the incoming voltage hundreds of times. The primary winding has two contacts as outputs. The secondary winding is enclosed between the positive contact and the end of the high-voltage wire. Violation of the integrity of one of the windings leads to the failure of the main task and, as a result, the absence of a spark.

It is better to start diagnosing the coil with the spark plug cap. There is a noise suppression resistor inside the cap, which also fails. You can check it with a multimeter, in resistance measurement mode. To the unscrewed cap, you need to connect the probes, one to the seat of the candle, the other to the end for the armored wire. Resistance is considered normal within 5 kOhm. If not, replace the cap.

On modern ignition systems, the coil is made in one piece with a wire and a tip. In this case, you need to test everything together. We connect one probe of the multimeter to the cap, the other probe alternately to the two contacts of the coil. Determine the resistance on the primary and secondary windings of the coil.

If the readings of the device do not correspond to the reference values, we change the coil or plug cap, if removed.

Electrical wiring

Another useful principle if you do not know why the spark on the scooter disappeared, then check the wiring. The reason that the spark has disappeared is trivial wire breakage, oxidation of contacts, connections or rupture of terminals. This problem is typical for any scooter, even China, even Italy.

By removing the decorative plastic sheathing, you can fully inspect the condition of the wiring. Pay attention to the ground wire from the coil to the body. The wire contacts are often oxidized and this leads to a decrease in voltage in the ignition system. The same problem exists in the contacts of the wire connecting the engine and the frame of the moped.

Thoroughly inspect the sensor and switch terminals. The wires may not contact or have poor contact, as a result, current is lost. To eliminate, clean each terminal from oxidation and carbon deposits, crimp the contacts and make sure that everything is firmly held in their sockets.

Another unlikely problem (but quite possible) is a break in the ground wire from the ignition switch. The wire is used to stop the engine and transfer the lock to the off state. In the event of a wire breakage and shorting it to the frame, even when the key is turned, the spark disappears.

Spark plug

The most common failure in the ignition system (including why there is no spark on the scooter) is a spark plug failure. The reasons are completely different: carbon deposits due to poor quality fuel (or because of oil); overheat; lean or rich air-fuel mixture and others.

You can assess its condition visually by unscrewing it from the cylinder. The working color of the candle is brick. But white, black indicates problems in her work. The best way to solve the problem is to replace it with a new one. If this is not possible, then clean it with a brush, rag or ignite it on a gas burner.

Spark testing is carried out in the following order:

  • The candle is unscrewed from the cylinder together with the tip.
  • The body of the candle is leaned against a metal mass.
  • The engine rotates with a foot or a starter, while sparks should slip between the spark plug electrodes.

What does the ignition system consist of?

Such a system on a scooter includes the following devices:

  1. Battery
  2. Starter
  3. Current generator
  4. Switch
  5. Coil
  6. Lock
  7. Candle
  8. Wiring.

Although all these elements are of different sizes, cost and complexity of the device, their importance in the proper operation of motor vehicles is almost equal. Failure of only one of the above listed elements, leads to malfunction of the entire scooter.

Each of these devices has its own possible malfunctions. We will discuss each device in order in which to repair.

Why there is no spark on a 4t scooter: causes and remedies

The main reason why the scooter won’t start is a malfunction of the ignition system. The main symptom of such a malfunction is a weak spark on the scooter or its absence at all. In the article you will learn about possible ignition breakdowns, diagnostics, and repair methods.


An expensive part in a scooter is a generator, even if it is China, or even Japan. It rarely fails, but it does happen. You can also diagnose the device using a multimeter by measuring the resistance on the generator winding.

Near the generator, locate the two wires coming out of the crankcase. One of the wires is red and black (comes from the pulse sensor), the second is blue and white (the main winding on the generator). Test both of these devices.

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To diagnose the pulse sensor, connect the multimeter probe to the red-black wire, and the second probe to ground. The nominal resistance of the circuit is 500 ohms. The generator winding is checked according to the same principle, but the probe must be connected to another blue-white wire. In this circuit, the resistance is 150-200 ohms. If the values ​​shown by the multimeter are not within the specified ranges, change the cause of the breakdown. Poor resistance means failure of the impulse sensor, or generator winding.

The reasons why the spark on the Alpha moped disappeared. Why is there no spark on the moped?

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Alternator and ignition sensor

You can check the generator and sensor without removing from the engine.

We transfer the tester to the alternating current measurement mode for the 2V range or, if your tester has such an opportunity, at 200mV. With one probe we touch any metal part of the scooter or engine, with the other probe the sensor wire (in the picture above it is labeled as a Hall sensor, but in fact it is an inductive ignition sensor). We turn the engine with a starter and look at the multimeter display. If the numbers are running on the display, then the sensor generates a signal and everything is in order with it. Otherwise, the sensor is faulty or the wire is broken.

We recommend reading:

Checklist for verification

Description of basic connections

The spark on the moped is gone what to do?

Failure of the motorcycle ignition system can be caused by a variety of reasons, ranging from small and insignificant, to serious ones that require major repairs of the vehicle. Fortunately, technologically, bikes are relatively simple (when compared to cars) and you can fix the breakdown on your own. Very often, the reason for the incorrect operation of the ignition system is that there is simply no spark on the motorcycle. In this case, it is necessary to accurately identify the part or assembly that led to the breakdown.

  • Spark Plug Inspection

If there is no spark on a moped or motorcycle, first of all, you must check the spark plug. It should not be excessively dirty and have a natural color. If the motor owner has a 100% working plug on hand, then test the operation of the ignition system with it.

Checking the battery charge

It happens that the fault of the loss of a spark on a moped or motorcycle is an insufficient battery charge. For a 12 volt battery, the permissible level is at least 9 volts. If the indicator is lower, then the reason for the inoperative candle has been identified.

Diagnostics of the ignition coil

The reason for the loss of a spark on a motorcycle may also be a malfunction of the ignition coil. To check the serviceability, it is necessary with the help of a low-power light bulb to make sure that the current is supplied.

Checking the generator and winding

Why is there no spark on a moped or motorcycle? Perhaps it is a faulty generator. First you need to make sure that the adjacent contacts are in working order. You also need to check the correct operation of the capacitors. In addition to the above, the reason for the loss of a spark on a motorcycle may be a defective generator winding.

Quite often, the lack of a spark on the candle becomes distributor and wires leading to / from it. First you need to inspect the coal. If the cause of the malfunction is not identified, then you need to check the high-voltage wires going to the distributor.

Regardless of whether the center of incorrect operation was identified or not, the problem was solved in a few minutes or hours, the owner of a motorcycle (moped) is recommended to visit qualified motor mechanics in the shortest possible time.

The reason is that it is very likely that a more serious defect in the bike’s operation will be overlooked, or even aggravate it.

The Spark On The Trimmer Disappeared

From practice.

There was such a case. The car owner, a person with driving experience, plus several neighbors in the garage, could not start the engine, although there was a spark during the check. With the ignition on, he brought the high-voltage wire from the coil to the engine ground and opened the contacts with a screwdriver, an excellent spark slipped.

When cranking with the starter, the engine did not start. Upon a detailed examination, I found that the plastic protrusion of the contacts, due to which they opened when they met the cams of the distributor shaft, broke off and the contacts simply did not open.

Replaced the contacts and the engine started from half a turn.

The second similar case, but with the ignition switch.

The six VAZ had already been towed for several hundred kilometers on the checkpoints, getting home. We then worked on the outskirts of the city. Another tug unfastened the rope and left, and the owner approached us with a request to sell the ignition coil, since, according to him, it is faulty and therefore there is no spark and the engine will not start.

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On examination, it turned out the following. A bolt was literally ripped out on the coil, where low-voltage power is suitable. We checked the coil, it is working, despite the dangling bolt.

Then they removed the contact group of the ignition lock, and so it turned out to be a similar picture. The plastic protrusion that commanded the contacts melted. When the key was turned to the ignition position, the lights on the dashboard lit up and the chain was in good order, when the key was moved to the start position, the ignition circuit was opened and the starter turned on wasted.

They removed the wires from the contact group, connected those responsible for the ignition and striking the wires responsible for the starter, they immediately started the engine. The owner was very upset that he paid so much for towing a serviceable car.


As you know, the engine requires two conditions: the presence of fuel and a spark, for its ignition. In cases where the spark disappears, starting the power plant becomes impossible.

This refers to a situation when the spark disappears completely, but there may be no spark on individual cylinders, when the engine starts to triple, an unstable start is observed, a decrease in dynamics and power against the background of an increase in fuel consumption.

The situations are different, as are the troubleshooting paths.

9 reasons why the spark is completely absent:

Spark plug

The electrodes of the spark plug can be covered with an oil coating, carbon deposits appear, sometimes completely covering the gap between the electrodes, breakdown of the insulator can occur, burnout of the electrodes and the spark plug fails.

Ignition coil

In the ignition coil there may be an interturn short circuit or a winding break.

Distributor distributor

In the distributor, contacts, a Hall sensor, a broken slider, or a crack in the cover may be faulty.

Egnition lock

The contact group may be faulty in the ignition lock (burning of contacts, melting of the plastic protrusion of the contact switching control.

High voltage wires

The problem in the wires can be expressed in their cracking, burning of the inner core and breakdown of the outer insulation.

Hall Sensor

In a contactless ignition system, the Hall sensor is responsible for interrupting the spark, the failures of which are often caused by loosening the bolts of its fastening, or by the breakdown of the sensor itself.

Crankshaft sensor

If DKV fails or poor contact in connection with the sensor, the engine will not start even if there is a spark in the ignition system. It is necessary to check the connection or replace the sensor.


In the event of a failure in the electronic engine control unit, there may also be no spark and it is necessary to carry out computer diagnostics of the unit.

Engine weight

Ground wire Poor contact or break in the connecting wire.

The procedure for checking the ignition system

In order to understand in what order it is necessary to start checking the system, we will briefly recall how it works.

The scheme of the classic ignition system

When the key is turned to the ignition position, power is supplied through the additional lock relay to one of the terminals of the low-voltage primary winding of the ignition coil. The coil has two low-voltage terminals, from the second terminal the coil is connected by means of a wire to the terminal of the distributor.

Further, when the engine is started, a high voltage is created in the secondary winding of the coil, which is fed through its central high-voltage wire to the central terminal of the distributor cover.

Then, the voltage is transmitted through the conductive part of the slider and the built-in resistance to high-voltage wires to each cylinder, according to the engine operating diagram. The wires, in turn, transmit voltage through the tip of the candle to the candle itself, between the electrodes of which, as a result, a spark jumps, igniting the fuel-air mixture.

In order that the voltage from the coil is not constantly applied in the distributor, contacts are installed that interrupt and connect the coil power circuit, depending on the position of the cams of the distributor shaft.
If the contacts burn, a spark may also disappear.

Let’s go back to checking the system

If the spark has disappeared, then it is necessary to find exactly where the circuit broke, starting from the fuses (the circuit is not protected on all models), the ignition lock and then according to the described scheme, step by step checking the serviceability of all its elements.

So, if when the key is turned to the ignition position, the warning lamps on the instrument panel light up, and there is voltage at the coil terminals, then the lock and the low-voltage circuit are working.

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Then you can check several items at once. To do this, when scrolling with a starter (an assistant is needed), a high-voltage wire is removed from one of the candles, but not completely, but holding the cap over the candle.

If the circuit is in good order, then clear clicks will be heard, otherwise the check must be started from the ignition coil.

Ignition coil

The armored wire from the ignition coil to the central socket of the distributor cover is removed from the cover and touches any metal part of the engine with a small gap. When cranking the starter between the wire and the metal part, if the coil is serviceable. A spark must pass.

If there is no spark, and the high-voltage wire is working properly, then the coil is out of order and needs to be replaced.

With a working coil, you must remove the distributor cover and first check the cover itself for cracks, and then the distributor slider.

Trambler runner

You can check the slider in two ways using the same high-voltage wire from the ignition coil or using a device, putting it on resistance.

In the first case, with a contact ignition system, the crankshaft must be turned so that the contacts close, then with the ignition on, bring the wire from the ignition coil above the slider with a small gap and open the contacts with a screwdriver.

If the slider is broken, then a spark will slip between it and the wire, if not, then the slider is not stitching to ground. Then you need to use a tester to check the integrity of the interference suppression resistor installed in the spacer plate of the slider.

If the resistor is burned out, then there will be no circuit and the slider will not be able to transmit voltage to the terminals of the high-voltage wires going to the engine cylinders. The slider needs to be replaced.

Contact group distributor

In the case when the slider is in good working order, it is necessary to inspect the contacts for their cleanliness and check whether they open when the distributor shaft is scrolled. If the contacts are working properly, then it is necessary to check the power wire coming from the ignition coil at its entrance to the distributor.

Often the plastic insert cracks and the voltage goes to ground, thereby breaking the power circuit.

No spark in a separate cylinder

Troubleshooting must be started immediately with the spark plug of this cylinder. The candle is turned inside out, its condition is inspected, and if it does not externally show any signs of malfunction (contacts burned out, there is no gap between the contacts, it is not in oil, etc.), then the candle is checked for serviceability.

To do this, on carburetor engines, the candle body is pressed against the engine block with a high-voltage wire on and the motor is scrolled by the starter. If the candle is in good working order, that is, it gives out a white and blue spark, then the problem must be looked for in the cylinder itself.

If there is no spark, then the wire of this cylinder is checked with a known good spark plug, and if a spark appears, then the problem is in the spark plug that was previously in the cylinder. A new candle is installed and the engine starts, if the cylinder is working, then the problem was in the candle, if not, then you need to check the compression in this cylinder, as well as the clearance in the valves of this cylinder (valve clearances are pinched) in order to identify the cause of the malfunction.

In the case when there is no spark when checking a known good spark plug, you need to check the condition of the high-voltage wire, the output to this cylinder in the distributor cover (a crack is possible).

On injection engines, it is not recommended to check the spark plugs by contacting them with ground, as the ECU and other electronic systems may fail. To check the spark on injection motors, there are special arrester devices, which are recommended to use.

Since spark plugs most often fail, we advise you to always have a spare kit so that you can quickly replace them on the way.


As you can see, the presence of knowledge about the structure and operation of the ignition system, as well as an automobile tester will help any car owner to identify and find a malfunction without contacting a car service.