Why Your ATV Backfires [8 Reasons]

Revving up your all-terrain vehicle (ATV) for a fun ride through the trails and woods can be a great experience, but if you’ve ever noticed loud popping noises coming from your ATV’s exhaust, then you’ve encountered backfiring.

Backfiring can not only startle riders and fellow enthusiasts but also indicate potential issues with your ATV’s engine and exhaust system.

In this post, I want to cover why ATVs will backfire and what problems your ATV might be having.

What Is Backfiring?

Backfiring is a problem that occurs in internal combustion engines, including those found in ATVs, side by sides, cars, motorcycles, and other vehicles. It refers to the sudden and often loud popping noise that comes from the engine or exhaust system when the engine is running or during deceleration.

The sound can often be confused with gunshots.

The reason an engine backfires is that the fuel is somewhere it shouldn’t be, and can be a sign something is wrong with your ATV or side by side. A normally operating ATV shouldn’t backfire, unless something is wrong.

Why Your ATV Is Backfiring

An ATV can backfire due to various reasons, and some of the most common causes include:

  1. Fuel mixture problems.
  2. Exhaust problems.
  3. Bad spark plugs.
  4. Dirty air filter.
  5. Vacuum leaks.
  6. Bad gas.
  7. Valve problems.
  8. Aftermarket modifications.

These will be your most common reasons for an ATV to backfire. In the next sections, I want to address each one and what you can do about it.

1. Fuel Mixture Problems

If your air to fuel ratio is off because you’re running rich (excess gas), the unburnt gas can ignite in the exhaust system, which leads to backfiring. The same can happen if you have too much air and not enough gas.

With carbureted ATVs, you can adjust the fuel and air mixture.

You will also need to check out the fuel pump and the fuel filter, especially on fuel injected ATVs. If the fuel pump is weak, you won’t get enough fuel to the engine and that will lead to backfiring. The same is true for the fuel filter when it gets dirty.

2. Exhaust Problems

A damaged or clogged exhaust system can disrupt the proper flow of gases, leading to backfiring as exhaust gases accumulate and ignite unexpectedly.

You will need to clean out your exhaust or get a new pipe for your ATV if it’s backfiring due to a damaged or clogged exhaust system.

3. Bad Spark Plugs

Bad spark plugs, ignition timing being off, and the spark plugs not being gapped correctly can lead to backfiring of your ATV.

4. Dirty Air Filter

A clogged or dirty air filter restricts airflow to the engine, affecting the air-fuel mixture, and it can lead a ATV backfiring.

Make sure to have a clean air filter that is properly oiled, or you can develop backfiring issues and a rough running ATV.

5. Vacuum Leaks

Any leaks in the ATV’s air intake system can affect the fuel-air mixture, contributing to backfiring.

Check your air intake hoses and pipes, especially if you modified them for mudding, to see if there are any cracks or damage.

I’ve seen hose clamps come loose over time and lead to all kinds of running issues, especially causing an engine to backfire.

6. Bad Gas

Gasoline that has gone bad may not explode in the cylinder, but instead in the exhaust because it’s hotter.

The unburnt fuel may even clump with other unburnt fuel until enough of it is collected, and then it explodes, causing the backfire.

Consider running a fuel system cleaner* in your ATV if you have bad gas or the ATV isn’t running right. I’ve had a few trouble ATVs with running and backfire issues return to normal with a good fuel system cleaner.

If the gas is old, the best thing to do is drain it and get some fresh gas in your ATV.

7. Valve Problems

Issues with the valves, such as incorrect clearance or seating, can affect combustion and cause backfires

The valves on your ATV control the in-flow and out-flow from the cylinders and need to be open and closed at the right time. If they’re open at the wrong time, fuel may leak out and into the exhaust system, where it will backfire.

8. Aftermarket Modifications

A lot of the backfiring I see today often comes from guys who make a lot of modifications to their ATVs.

They either put the wrong pipe or snorkel on, or add a turner that messes everything up.

The ATVs today are a lot more complex and need correct remapping when certain accessories are added, and not doing it correct can cause an ATV to backfire.

Get A Pro

If you’re not sure where to start or tried everything, the best thing you can do is get a pro to look at your backfiring ATV.

There can be odd flukes that can cause an ATV to backfire that are impossible to add to this post. Just one example I’ve seen recently was a rat who chewed on the right ignition wire, causing the ATV to misfire and then backfire.

The proper repair shop will have the tools and the software from the manufacturer to see what error codes are showing up and how to fix it the best way possible.