When you start your lawn mower or small engine, you turn the flywheel and its magnets pass the coil (or armature). This creates a spark. … Once the engine is running, the flywheel keeps rotating, the magnets keep passing the coil and the spark plug keep firing based on a specific timing.
How is a spark created in an engine?
When the high voltage produced by the ignition system is applied between the center electrode and ground electrode of the spark plug, the insulation between the electrodes breaks down, current flows in the discharge phenomenon, and an electrical spark is generated.
What causes an engine to have no spark?
Misfiring can be caused by loss of spark; imbalanced air/fuel mixture; or loss of compression. … 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.
How much voltage is needed to create a spark?
The ionized gas becomes a conductor and allows electrons to flow across the gap. Spark plugs usually require voltage of 12,000–25,000 volts or more to ‘fire’ properly, although it can go up to 45,000 volts. They supply higher current during the discharge process resulting in a hotter and longer-duration spark.
What is the effect of less spark plug gap?
A narrow gap leads to weak spark to effectively ignite the fuel-air mixture. On the other hand, a gap that is too wide might prevent a spark from firing at all or may result in misfiring at high speeds.
How do I know if my small engine coil is bad?
One of the symptoms of a bad lawn mower ignition coil appears when you are mowing the lawn and the mower gets hot and literally shuts off. The mower must cool down over a period of time and will start and run for awhile until it gets hot again, at which time it will shut off again.
Why is there no spark on my lawn mower?
If you don’t see a spark on the tester, there may be a problem with the ignition coil of the flywheel to which it’s attached. The ignition coil doesn’t frequently develop problems, but the connection between the flywheel and coil or between the starting pulley and flywheel can wear out, and the coil may not be turning.
How do I fix no spark?
First Confirm Your Engine Has No Spark.
- Disable the fuel system by removing the fuel pump fuse or relay.
- Insert a spark plug tester into the plug boot and ground it on a piece of metal on the engine.
- Finally, Have someone crank the engine and watch for spark.
Can a bad ground cause no spark?
Bad grounds can cause no spark issues though. It can cause the ground to ground through the ecu frying it. If you get a single spark when turning on the ignition then nothing when cranking it’s the ecu. It’s a really good idea to go over all your grounds on a regular basis anyway.
How is no spark condition diagnosed?
If the engine has no spark, check for voltage at the coil positive terminal when the ignition key is on. If there is voltage, the problem is on the trigger side of the coil (pickup, crank sensor, ignition module or primary wiring circuit).
How much voltage is an arc?
To get any current flow at all you must first ionize, or breakdown the air. The breakdown voltage for air is roughly 3 million volts per meter – that varies with pressure and moisture content – so you need about 300,000 volts to start the arc.
Can electricity jump gaps?
Air is normally an electrical insulator; electricity can’t jump out of a wall socket and shock you because the surrounding air does not conduct it. But very high voltages have enough energy to turn air into a conductor, allowing electricity to jump the gap.