Harley Davidson No Spark Troubleshooting

Problems regarding no-spark and ignition coil issues

To produce the high-spark voltage, your ignition coil requires some conditions to be met. If they are not in proper condition, chances are high that they will cause a problem with the ignition coil.

  • Power: There are two positions in the ignition coils- ‘start’ and ‘run’. In the ‘start’ mode, the switch ignites the starter motor. The full battery voltage is channeled in the coil and meanwhile, the engine cranks up. When it starts, the switch is moved to ‘run’ mode. You need to look closely at the battery. If the supply of the voltage to the ignition coil and the circuit does not seem continuous or inconsistent, there might be something faulty.
  • Signal: Voltage would pass through the coils if no external signal is given as input. This will not induce any secondary spark. A switch or signaling device can trigger the interruption in the circuit, followed by a high voltage in the coil windings. This transformation of voltage coincides with each spark. Modern circuit systems can sense the need for spark compared to the older ignition systems. This creates a hall-effect switch or crankshafts the position sensor. Test the components of this ignition system to determine if there is any faulty coil on your bike.
  • Flow: Usually, ignition coils produce a powerful secondary voltage. It will pass through the hollow hose to the distributor cap. But it will fail to fire the coil if it goes through a wide gap or thick corrosion. Make sure secondary spark conductors complete the circuit with good connections and proper insulation so that it can deliver a successful voltage.
  • Open circuits: If any conductive element is damaged or opened, this can turn out to be dangerous as it creates an open circuit. The continuity of the coil windings can be tested with an ohmmeter. Broken connections will have adequate resistance that can yield an open circuit. Besides this, poor engine and battery condition should also be checked along with this.

How do you know if your Harley coil has turned bad?

Here is a list of the symptoms to identify a bad ignition coil in your Harley-

  • Poor fuel economy: Your bike requiring more fuel than usual or running out of them faster than usual.
  • Engine backfiring: When your engine runs either lean or rich. When fuel is present more than air, it is rich and otherwise, it is lean.
  • Vehicle stalling: Bad ignition coil will cause your bike to stall while the engine is working.
  • The engine does not start: one of the most common signs of a bad ignition coil is when the engine fails to start.
  • Rough idling: Weak ignition coils make the bike jerk. Even when you accelerate the engine it will not hike the power and will make loud noises instead.
  • Engine misfiring: If you notice noisy sputtering or coughing-like sounds after ignition, that might be the causation of a bad ignition coil.

How can you diagnose a no-spark?

Before you can troubleshoot any issue, it is always a good idea to be sure about the problem with the proper diagnosis. If you see that the engine cranks up normally but does not start, this might be caused by either no fuel, no spark, or no compression.

To check whether or not it is caused by no spark, use the following method.

  • Detach the air inlet tube from the throttle body. Push the throttle top open. Then, spray little aerosol starting fluid into the engine.
  • Crank the engine.
  • If the engine does not start, it has a spark problem.

Harley Davidson No Spark Troubleshooting

Harley Davidson No Spark Troubleshooting

Resolving the no-spark issue of your Harley Davidson motorcycle

To get started with this, you need to remove a spark plug and re-attach the plug wire. You need to ensure that the plug’s metal base is grounded by the insulator. I am talking about the ceramic insulator if you are not sure what portion is the insulator. The next part requires a friend of yours. Tell him to turn on the starter or the ignition switch. You keep an eye on the connector’s grounding electrode.
At this stage, if you see a blue or yellow spark bridge fills the gap, then you are good to go. It means you have enough fire that can ignite the fuel in the cylinder.

If you do not see any sort of spark, turn your bike on. Sometimes, ignition switches can malfunction and might not work properly under that situation. Besides, if your Harley has a security system installed, it might not be getting the juice properly. And that might hinder the bike from turning on.

Now, figure out the coil powered switch. Get a multimeter or lamp tester to check if the current flows from the coil and reaches the spark plug cap. You should get an on and off reading for every revolution of the engine every time someone tries to start the engine. If you find that, you have to replace the faulty spark plug with a new one following the same methods described previously. If it fails to receive AC power, you have to replace the spark plug with a wire or cap.

If your bike is quite old, it is better if you can check the current flow from both sides of the engine and condenser points. Closely check on the parts and make sure they are in decent condition. If the parts are very old or the ignition system feels weak, replacing parts will help you to troubleshoot the issues.

Frequently Asked Questions (FAQs)

Why my ignition coil is not firing?

The main reason that causes the ignition coil to not fire is that when anything hinders coil voltage from the channel to the electrode gap at the end of the spark plug. This can involve damaged, worn out, poor quality spark plug or a cracked distributor.

How do you replace an ignition coil?

At first, you need to disconnect the negative terminal on your battery. Then find out the coil that needs to be replaced and disconnect the wire that leads to the bad coil. Then you have to unwind the bolts and discard the faulty coil, followed by installing a new one. Before setting that up, ensure the compatibility of the new coil with your engine.

How much does an ignition coil cost?

You can find a new ignition coil for $80 to $300. In general, most of them cost around $150.

How can I test an ignition coil?

You can check your ignition coil in your Harley Davidson motorcycle by following some steps.

  • First, you need to let the engine cool off if it is already in the ignition. It is essential for proper diagnosis. After that, you need to manually disconnect the two spark plug wires from the coil. Then using an SAE wrench, unwind the smaller connections on the coil.
  • Next, set the ohmmeter resistance on the “Rx1” setting. Measure the resistance across the two smaller terminals in the coil which should read 2.5 to 3.1 ohms.
  • Repeat the previous step, only this time set the resistance to the “Rx1000” setting, and the meter should read 10,000 to 12,500 ohms.
  • If you find the readings of either of the two trials falling under or above the mentioned range, it is an indicator of a faulty ignition coil.

What are the indicators of a bad ignition coil?

Look out for the following signals to determine if the ignition coil is bad-

  • Engine misfires, weak power, and acceleration, reduced gas mileage
  • If the engine light comes off
  • No-start issue, bike stalling

What does a single-fire ignition do?

A single fire ignition fires each spark plug by using separate coil windings and electronics. It eliminates backfiring problems and improves idle quality.

What is the difference between single fire and dual fire ignition coil?

Double fire starts frameworks fire both the spark plugs from a solitary curl simultaneously. Most of the flash energy goes to the chamber under pressure while a little segment goes to the chamber on the fumes stroke causing a little squandered sparkle. Single fire starts to separate the terminating beats, just terminating the chamber under pressure. The fundamental preferred position of double fire frameworks is straightforwardness and ease. The benefit of single fire frameworks is smoother motor activity and the end of the popping that occasionally happens when long length camshafts are utilized. There is no pull advantage with single fire start frameworks.

How long an ignition coil lasts?

As per general observation, an ignition coil is supposed to last somewhere around 100,000 miles. It can extend this parameter, as well as can be damaged prematurely.

Should I replace all the ignition simultaneously?

As ignition coils cannot be repaired but to be replaced, sometimes it can lead to some other problems in the remaining two coils. Thus, some technicians suggest replacing all three rear ignition coils when either of them seems to be causing any trouble. Besides them, replacing all the spark plugs can ensure longer-lasting coils.

Can a bad spark plug damage a coil pack?

Yes, a bad spark plug can be one of the conditions that can damage a coil pack. So, a bad spark plug should be replaced to prevent any sort of damage to the ignition coils or any coil packs.
Abdulla Zatar
About Abdulla Zatar

Hi, I’m Abdulla! Your go-to tech troubleshooter! Sharing my knowledge so that you can fix your tech issues with ease. Let’s make fixing things easy and fun!

4 thoughts on “Harley Davidson No Spark Troubleshooting”

  1. 9 just bought a 05 fat boy 95 cu in motor. was running great. it started leaking oil the day after i bought it i might have pushed it a little at first but not over 80
    leaks, about a teaspoon overnight letting it set, it is not coming from any of the o rings, they have been replaced, it looks like it is coming out where the chain and belt go into the motor, but from underneath towards the the chain/belt side. now it is dying while im riding it, the gas gauge quit working, then starts again, the apeed ometer works and sometimes it doesnt. now it is cutting out and dying. what happened, im lost need some help, always wanted a harley.

  2. I’m trying to fire up my S&SV145inch. Ive got power to coil but no spark ove changed oils ,ignition plugs &wires and still no spark I even grounded off powdercoating for better ground. I’m stumped

  3. I’ve got no spark, already fully established that, what I want to know is what other parts can cause the bike not to have spark.


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