What causes a weak spark on a motorcycle?

Asked By: Robina Kuhnemann | Last Updated: 3rd February, 2020
Category: automotive auto parts
4/5 (3,257 Views . 14 Votes)
Weak spark occurs when the primary side of the ignition coil short circuits within the coil windings.. (Less coil windings to flow through generates a lower voltage spark (Weak Spark) And to test the coil , you need to know the primary and secondary resistance values to determine if it's farked..

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Furthermore, what causes weak spark?

Loss of spark is caused by anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. This includes worn, fouled or damaged spark plugs, bad plug wires or a cracked distributor cap.

Also, what causes weak spark on ATV? Since the ignition is AC excited (no battery needed) - a weak spark tells you the pulse generator coil is telling the CDI unit to fire the coil - generally speaking, having a weak, but consistent spark rules out the pulse coil, so the culprit is either a bad ground, the CDI unit or the stator.

Also asked, what causes weak spark on outboard motor?

Weak spark may cause starting and running difficulties as there may not be enough heat generated in the spark to accomplish ignition of the fuel/air mix in the combustion chamber. Common reasons for weak spark are faulty flywheel magnets and faulty stator.

How do you know if your spark is weak?

The engine will be weak, the unburned fuel will foul the spark plug, and the exhaust will pop. If the mixture is excessively lean, the engine will misfire since the fuel molecules in the intake air are too far apart.

34 Related Question Answers Found

How do I fix no spark?

If you do not see a spark, there is an ignition problem. Remove a plug wire and insert an old spark plug or a spark plug tester into the end of the wire (the plug boot). Place the spark plug on a metal surface on the engine, or ground the spark plug tester to the engine. Then crank the engine to check for a spark.

Can a bad ground cause weak spark?

It is, but the lack of one (or a fualty one) can and will create a weak spark. Basically, you need proper voltage to the coil and a good ground inside the dist for the point plate, along with a good ground path for the dist itself.

What are the symptoms of a weak ignition coil?

Usually a faulty ignition coil will produce a few symptoms that alert the driver of a potential issue.
  • Engine misfires, rough idle, and loss of power. One of the most common symptoms associated with a faulty ignition coil is engine performance issues.
  • Check Engine Light comes on.
  • Car is not starting.

Can stator cause weak spark?

The stator coil generates the power for the spark plug and other accessories on small engines Without a stator there would be no spark at all, meaning the engine won't run. While a stator is dying, it can produce a weak spark, causing the engine to miss or run poorly. Symptoms are often worsened as the engine warms up.

Will a bad condenser cause weak spark?


When the points open to disconnect the ground connection you get instant spark. If you do have this good ground connection through the points, then you may have a bad condenser. Weak spark is often the result of a bad condenser (and it's a cheap part to replace).

How do you test an ignition condenser?

Touch the red lead to the hot connector on the condenser. Place the black lead to the metal case on the condenser. The meter's needle should jump slightly to the right (toward 0-ohms), then should drop back to the left towards infinite resistance). Hold the leads in place for 15 to 20 seconds.

Will a bad coil cause weak spark?

Of course, a faulty ignition coil will have a bad influence on the engine's performance. A weak spark is the first sign that the ignition coil may be failing. During acceleration, the air and fuel that is forced into the cylinders extinguish whatever spark there is, which causes the car to stall.

How do I check the spark on my outboard motor?

Hold the plug wire about 1/4 inch from the powerhead, not over the spark plug. Turn the motor over one time only, either with the recoil starter or the electrical starter. Watch for a spark and observe its character. A good, strong spark means the air and fuel mixture in the cylinder will be ignited properly.

Can a CDI box cause no spark?

The CDI is not easy to diagnose because the observable symptoms of a faulty CDI box can lead to different directions. Sometimes, a bad CDI does not cause sparks at all. Again, when a CDI box is about to go bad, it can lead to misfires, issues with starting, rough running or even stall the motor.

What causes a boat not to start?


Why Your Boat Won't Start
  • Empty gas tank.
  • Gas tank air vent not open.
  • Fuel lines kinked or severely pinched.
  • Water or dirt in fuel system.
  • Clogged fuel filter or screens.
  • Motor not being choked to start.
  • Engine not primed -- pump primer system.
  • Carburetor adjustments too lean (not allowing enough fuel to start engine)

What does a trigger do on an outboard motor?

Your outboard trigger tells the switchbox when to "fire". The inner ring of your flywheel has magnets which pass close to the triggers coils. Each time the magnet passes, the trigger sends a low voltage "signal" to the switchbox.

How does boat ignition system work?

They consist of the ignition switch, a coil to store and release enough energy to fire the spark plugs, distributor to distribute the spark to the correct cylinder at the correct time, and the spark plugs which fire to cause combustion in each cylinder.

How do you test a Mercury outboard power pack?

Place the positive probe of multimeter on the green and white striped terminal wire pin and the negative probe of the multimeter on the terminal pin for the red and yellow wire. Primary resistance should be less than 1 ohm, about 0.38 ohms and 0.78 ohms.

How do you test a ignition coil?

Connect your multimeter to the positive terminal or pin of your coil, and to the high output terminal that goes to the spark plug. Most ignition coils should have a secondary resistance falling somewhere between 6,000 to 10,000 ohms;however, refer to manufacturer specifications for the correct range.

Why does my car turn over but not start?


When your engine cranks but won't start or run, it could mean your engine is having trouble producing a spark, getting fuel, or creating compression. The most common causes are in the ignition (for example, a bad ignition coil) or fuel system (for example, a clogged fuel filter).

What causes yellow spark?

A yellow glaze on the spark plug's electrode and the tip can inhibit conductivity, keeping the spark from being able to jump the gap. Causes may include a stuck choke, misadjusted or heavy carburetor float, a leaky injector or carburetor needle valve, low coil output or high resistance in your spark plug wires.

What color should the spark be on a spark plug?

The strength of the spark is revealed in the color. A red or yellow spark is weak and probably will not spark in the cylinder. A blue or white spark is strong and has enough voltage to fight across the spark plug gap even under pressure within the cylinder.