No Spark? Try These Fixes Before Replacing Your Ignition Module

We’ve seen many customers with no spark issues on their 2-stroke machines. They often replace the spark plug first, which is a good start. But when that doesn’t solve the problem, the next step is usually to buy a new ignition module.

In most cases, the ignition module isn’t the issue.

Top 3 Common Misdiagnoses Before Replacing the Ignition Module

1. “The spark plug is new, so the module must be faulty.”
   Even new plugs can fail. Always test with a known good plug and a spark tester.
2. “There’s no spark, so the ignition module is dead.”
   A shorted kill switch wire is often the real issue. Disconnect it and test again.
3. “I replaced the module but it still won’t start.”
   If HT leads, spark plug boots, or flywheel gaps aren’t checked, the problem persists even with a new ignition module.

Before spending money on a new module, check these areas to save time and hassle.

1. Use a Spark Tester

If you’re unsure whether there’s spark, a spark tester is a cost-effective and reliable tool for confirmation.

We recommend the L&S Engineers Spark Tester (part no. 015 800), designed specifically for 2-stroke machines. It’s user-friendly and eliminates guesswork in spark testing.

2. Check the Kill Switch (On/Off Switch)

A faulty or shorted kill switch is a common cause of no spark.

• Ensure the kill switch is in the ON position.
• Disconnect the kill switch wire from the ignition module.
• Pull the starter cord and check for spark.
• If spark returns, the issue is likely with the switch or wiring, not the ignition module.

h33. Isolate the Ignition Module by Disconnecting the Positive Wire

To determine if the ignition module is affected by other electrical components:

• Ensure the kill switch is in the ON position.
• Disconnect the positive wire feeding the ignition module.
• Pull the starter and check for spark.
• If spark is present when isolated, the fault is likely with wiring or switches, not the ignition module.

h34. Inspect the HT Lead (High Tension Lead)

The HT lead connects the ignition module to the spark plug boot and carries the high-voltage spark.

• Look for cracks, brittleness, or exposed wiring.
• Ensure connections at both ends are secure.
• Replace the HT lead if it is damaged or worn.

h35. Check the Spark Plug Boot

The rubber spark plug boot can deteriorate over time.

• Check that the metal clip inside grips the spark plug firmly.
• If the boot is cracked, loose, or damaged, replace it.

h36. Clean the Flywheel and Ignition Module Area

Rust, dirt, or oil on the flywheel or ignition module can disrupt spark generation.

• Remove the starter assembly.
• Clean the flywheel and ignition module surfaces thoroughly.
• Check and set the air gap between the flywheel and module to approximately 0.3 mm (refer to your machine’s manual).

When the Ignition Module Is the Problem

Sometimes the ignition module fails only when the machine warms up:

• The engine runs well when cold.
• After a few minutes, it cuts out with no spark.
• It may restart after cooling down.

This heat-related failure is a classic sign that the ignition module needs replacing.

Need Help?

If you’ve checked everything and still need assistance, our experienced sales team is here to help.

We stock genuine ignition modules and parts compatible with UK machines and can advise on the correct components.

Call us: 01543 378189
Email us: sales@lsengineers.co.uk