The ignition device is the starting system for your small engine. Even if it is you begin the engine with a pull rope or the rotate of a crucial on an electrical start motor, you're relying ~ above the ignition mechanism to develop a spark inside the combustion chamber.

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When you begin your lawn mower or little engine, you turn the flywheel and its magnets pass the coil (or armature). This creates a spark. The ignition system coordinates the timing so the the spark will ignite the air-fuel mixture in the combustion chamber simply as that reaches maximum compression in every engine cycle- thus, maximizing the engine’s power.

Once the engine is running, the flywheel keeps rotating, the magnets store passing the coil and the spark plug keep firing based upon a details timing.


Types the Ignition Systems


Solid-state systems: the more modern option, these systems use a small transistor in the coil or armature come close the electric circuit that travels v the spark plug result in the spark plug(s)

Breaker allude systems: supplied on engines made prior to 1980, these solution use a mechanically switch instead of a transistor to close the electric circuit provided to produce a spark


How To check the Ignition Coil in Your little Engine


The coil is probably the most basic thing come check and therefore the very first thing to examine when embarking ~ above ignition system troubleshooting.


Testing the Coil or Armature

Clip one finish of the spark tester (service part number 19368) to the ignition cable and the various other grounded to the cylinder head

Spin the flywheel rapidly (at least 350 RPM) and also watch for spark in the tester window

If the spark jumps the tester gap, her ignition coil is working fine. If not, it demands to it is in replaced.

Engine quits if running? Hook the tester up in between the ignition cable and the spark plug and also start the engine. When it stops, screen the window.


Common failure When testing Coils

Be certain to unhook the coil native the devices wiring harness and also the engine's wiring harness and use the spark tester. Make certain the coil grounding lead is no shorting out against a piece of sheet metal

DO NOT affix the tester to the spark plug for this test. The engine may start. Without the ground connection lead installed, friend won't have the ability to turn it off


Replacing Ignition Coils or Armatures

An ignition armature have to be set at a an exact distance indigenous the flywheel. Her engine repair manual will carry out the appropriate gap for her engine. Common armature space ranges space .006 - .010" and .010 - .014". Armatures are frequently packaged through a shim to aid in setup the gap.

Unhook the spark plug wire and also secure it, removing any type of batteries, if equipped

Remove the old ignition coil (armature) mounting screws

Disconnect the avoid switch cable from the flywheel brake and remove the coil

Attach a instead of coil making use of mounting screws

Push the coil (armature) away from the flywheel and also tighten one screw

Turn the flywheel for this reason the magnets room on the opposite side from the ignition coil (armature)

Place the proper shim between the pickled in salt of the flywheel and also the ignition armature. If holding the shim, revolve the flywheel till the magnets room directly surrounding to the armature

Loosen the chop screw therefore the magnets traction the ignition armature versus the flywheel and shim. Then, tighten both mounting screws and rotate the flywheel until the shim slips free

Reconnect the avoid switch


Insert the spark plug lead on one finish of a spark tester and attach the tester's alligator clip come ground, such together an engine bolt

Place the devices stop switch regulate in the turn off or protect against position. If the engine is not associated to the equipment, soil the prevent switch cable to the cylinder

Attempt to start the engine using the rewind cord or crucial (if equipped)

There have to be no spark. If a spark appears, check the protect against switch because that damage

Place the protect against switch manage in run or begin position

If the engine is not connected to the equipment, make certain the avoid switch wire is not grounded

Attempt to start the engine

A spark should be clearly shows in the tester. If no spark appears, examine for damaged wires, shorts, grounds or a defective avoid switch.

Once girlfriend have confirmed that the stop switch is working, reconnect the spark plug lead.


Because the ignition module is electronic and also does no utilize relocating components, it is usually one of the many reliable component of the engine. Once it go fail, the is usually because of heat resulted in from improper wiring the the ground cable to battery voltage.

If the engine go not produce spark, other areas of the ignition system should be checked prior to focusing top top the ignition module as source of failure (see above).

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If no fault is discovered, the ignition module itself may need to be examined. To ideal determine the cause of failure, please consult an Authorized Dealer.