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ATV Backfiring: Common Causes and Solutions

Starting or driving your ATV, and you hear a popping or cough-like sound? That’s your ATV backfiring! While it doesn’t mean it’s normal, it’s one of the most common issues with ATVs you need to be familiar with, especially since there are several reasons why an ATV backfires.

So, why is your ATV backfiring? Your ATV backfires mainly because of an improper air-fuel ratio resulting from issues with your exhaust pipe, muffler, air or fuel filter, or carburetor. Your ATV can also backfire due to a faulty ignition due to spark plug or ignition coil issues.

Confused? Overwhelmed? Well, let’s discuss all these causes in more detail to help you find the real reason your ATV is backfiring. These pieces of knowledge will also help you prevent some of these issues from happening. I will also share the specific solutions to these problems so you can resolve them as soon as they happen.

ATV Rider Wearing Orange and Blue Riding Dirty Quad

ATV Backfiring: The Two Common Causes

Cause 1: Imbalanced Fuel-Air Mixture

Normally, a well-balanced amount of air and fuel enters your ATV’s combustion chamber. The spark plug will ignite this mixture to deliver power to your vehicle’s engine, propelling it forward.

Now, any disturbance in the air-to-fuel ratio will make your ATV backfire.

Why Does My ATV Backfire When There’s an Improper Fuel-Air Ratio?

Two things can occur when there is an imbalanced mixture of air and fuel entering your ATV’s combustion chamber:

  • Too much fuel and too little air
  • Too much air and too little fuel

When there’s too much fuel, the air gets choked up or won’t flow at the same time as the fuel, while the excess leaks outside the ATV’s combustion chamber. It means that all the fuel doesn’t get burned at the same time, leaving unburned fuel in your ATV’s exhaust system.

As soon as your ATV’s exhaust valve opens again or the engine’s exhausting process starts, the unburned fuel will ignite. Since it happens outside the chamber, it will produce a loud popping sound.

Another contributing factor to this backfire sound is the influx of air that wasn’t able to flow freely earlier. The same goes for when there is too much air. The extra air produces a popping or cough-like sound because of the influx of extra air in the system.

Why Is There a Fuel-Air Mixture Imbalance?

Many problems can cause an imbalanced air-fuel mixture. But the main reasons include the following:

Exhaust Pipe Issues or Muffler Changes

Did you replace any of your ATV’s exhaust system parts? Perhaps you added a muffler. If you did so, your ATV might be backfiring because of these changes, as you might have replaced them with an incompatible or mismatched unit.

That said, even the tiniest hole or crack in your ATV’s exhaust system can also cause an imbalance in the air-fuel mixture.

Dirty or Clogged Air and/or Fuel Filter

Remember that your vehicle gets exposed to debris, mud, dust, and dirt when you drive it on trails. These elements will slowly collect in your air filter until it becomes partially and fully clogged.

Meanwhile, the fuel filter will collect dirt and fuel byproducts or components. Like with the air filter, it can become partially and completely clogged after some time.

Needless to say, a dirty filter will slow down the flow of the air and fuel. On the other hand, clogged filters will prevent either or both the air and fuel from reaching the combustion chamber.

Insufficient Fuel Pressure or Pump

An insufficient fuel pump or weak fuel pressure means you’re supplying your ATV with less fuel than expected. This, in turn, prevents your vehicle’s engine from guzzling up enough fuel in its combustion chamber.

Dirty, Clogged, or Faulty Carburetor

Whether you own the latest ATV model or an older one like the 2005 Polaris Phoenix 200, the carburetor can become dirty or clogged. That is most especially when you haven’t ridden your ATV for quite some time and haven’t stored it properly.

Like your ATV-riding gear (view on Amazon), you must store your vehicle clean and dry. Not only that, but you also have to ensure fuel doesn’t sit in its tank for a long time.

The old fuel will slowly thicken and degrade, clogging your ATV’s carburetor jets. A clogged-up carburetor will reduce fresh air intake, leading to an air-fuel mixture imbalance in the combustion chamber.

At times, there might not be enough fuel in your ATV because its idle circuit (the part responsible for controlling fuel when your ATV is running at a low RPM) is extremely lean.

It can also be possible that you have a faulty carburetor. If this is the main cause of air-fuel ratio problems, backfiring happens more frequently than the other causes. You will also notice that your ATV isn’t just backfiring—it’s accompanied by a physical jolt.

Faulty Ignition

When asking why an ATV backfires when trying to start it or at some point while you’re riding or driving it, another common answer you’ll hear is ignition issues. Any problems with the ignition will produce an irregular, extremely loud popping sound combined with a power loss.

Why Does My ATV Backfire When It Has a Faulty Ignition?

In normal conditions, your ATV engine’s heads and blocks resonate synchronously for the strokes to occur at the same time. If they don’t sync, there will be a delay in igniting the fuel.

That said, the process normally starts when your ATV’s fuel chamber is closed, and the ignition happens when the chamber is open. It means that with a slight delay, the process would start when the chamber begins to open or as soon as it opens, producing the backfire sound.

What Are the Common Ignition Issues Causing Backfire? 

Your ignition might malfunction because of a worn, torn, or damaged spark plug. A problematic spark plug will continuously ignite fuel in the ATV’s exhaust or intake rather than the fuel in the combustion chamber.

Apart from the spark plug, your ATV can backfire because of malfunctioning or broken ignition coils. This problem will prevent the ignition from operating as expected.

How To Fix ATV Backfires

Now that we know why an ATV backfires when trying to start it or in the middle of a ride, it’s time for you to learn how to resolve each issue.

Fixing Imbalanced Air-Fuel Mixture

Adjust Throttle Settings

When there’s a problem with the equilibrium between air and fuel, the first thing you need to do is adjust your ATV’s throttle setting using its throttle wheeler (fuel mixture screw). This feature is responsible for increasing or decreasing the fuel entering your ATV’s engine when idle. You will need to make some adjustments to play around your vehicle’s air-fuel ratio.

Here’s what you need to do:

  1. Locate the wheeler or screw, usually on or near the ATV’s carburetor.
  2. Adjust it and see how your ATV’s engine responds as you idle.
  3. Continue adjusting until you no longer hear a popping or cough-like sound.

Install a Compatible Muffler 

If you have installed or plan to install an exhaust muffler, ensure it fits perfectly. Simply measure the dimensions and look for a product that matches the size.

Even a small hole in the exhaust can cause this problem. Find the right replacement part, check the OEM’s website, give them a call, or talk with a mechanic.

Fix or Replace the Damaged Exhaust Pipe

If your ATV’s exhaust system has holes or cracks, you can temporarily cover them with exhaust tape, standard epoxy, high-temperature metal sealant (view on Amazon), or both. First, clean the exhaust pipe with acetone in a clean microfiber cloth. Then, gently sand it with sandpaper.

When using exhaust tape, make sure you wrap it around the pipe. Also, don’t forget to read the manufacturer’s instructions because every exhaust tape is different. Some work on warm exhaust pipes, while others require you to wet the tape before wrapping it around the pipe.

You may also apply well-mixed epoxy on the crack or hole. Likewise, you can apply epoxy and then wrap the area with exhaust tape.

What if the exhaust pipe has a large hole or crack? You will need a patch to cover it. To do so, here’s what you must do:

  1. Measure the hole or crack.
  2. Cut an aluminum using the measurement you just obtained.
  3. Cover the hole or crack with epoxy or sealant.
  4. Place the patch over the epoxy or sealant.
  5. Press the patch to secure it. It’s okay even if the epoxy or sealant leaks out of the patch.
  6. Apply epoxy or sealant to the edges of the patch to secure it further.

Now, for three-inch (or larger) holes or cracks, it’s best to replace the pipe.

Clean or Change the Filters

Locate your air and fuel filters and inspect for large sediments and deposits. If they’re full of gunk, replace or clean them, depending on your ATV filter type. Plastic-made ones are disposable, while foam filters are washable.

Bonus Tip: I recommend you use high-quality fuel products or those with fewer impurities and additives. They ensure slower gunk and debris buildup on your fuel filter.

Clean or Replace the Fuel Injectors

If you haven’t had your fuel injectors cleaned in a while, it would be best to do so to remove any gunk clogging them and preventing the fuel from flowing freely.

I recommend investing in a good-quality fuel injector cleaner to ensure you remove even the toughest dirt and debris. These products will also clean your fuel filter, so you’re hitting two birds at a time.

Now, it would be best to check the actual condition of your ATV’s fuel injectors instead of just cleaning them. You can do so with the help of a multimeter.

With your ATV off, carefully disconnect the fuel injector’s electrical connector. Then, take the resistance reading using your multimeter.

Compare the reading with the readings in your ATV’s service manual, or check the brand’s website. This will help determine if you need to replace your fuel injectors.

Clean the Carburetor Jets

Unlike with cleaning your ATV’s fuel injectors, it would be best to have a professional clean your carburetor jets. While carburetor cleaners work, removing and disassembling the carburetor to clean each part thoroughly is a more practical and safe solution. Of course, that is unless you have been DIYing for a long time.

Fixing a Faulty Ignition

Replace the Spark Plug

If the symptoms of your ATV backfiring seem to point to a faulty ignition, you first need to check your ATV’s spark plug. If it’s worn, torn, or damaged, purchase a new one and replace it.

Replace the Ignition Coil

Like with your ATV’s spark plug, inspect the ignition coil for any sign of damage, tear, or wear. If there are any, then replace or have a professional replace it.

Identifying and Fixing the Causes of ATV Backfires

Your ATV can backfire for two general reasons, air-fuel ratio and ignition problems, that root from several causes. But don’t worry; most of these have not-so-expensive solutions, from cleaning filters and injectors to replacing small parts like spark plugs.

However, they can cost you more when you don’t address what’s causing the backfire ASAP. They can take a toll not just on one specific part of your ATV but will eventually lead to damages to other parts.

So, learn this guide by heart or keep it in mind to use as a reference once your ATV starts to backfire. Also, remember that preventive maintenance is always better. So, inspect your ATV regularly, clean what needs to be cleaned, and replace any parts that show early signs of overuse.