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Why an ATV Backfires: Common Reasons and How to Fix the Issue

Why an ATV Backfires: Common Reasons and How to Fix the Issue

Were you recently driving your ATV and noticed a sudden and loud bang or pop, potentially causing you to jolt forward? It is likely that this was resulting from your ATV backfiring- something that is relatively common but can still be concerning.

ATVs commonly backfire due to the imbalance of air and fuel sparked outside of the combustion chamber. This minor explosion takes place in the engine’s intake or exhaust and can cause the vehicle to shut off. Common reasons include issues with the fuel/air mixture, carburetor, ignition, or fuel pump.

Though this might sound (and feel) incredibly intimidating, you should know that it is a relatively common occurrence with ATVs. With that in mind, you should take caution, but likely will only need to take action should this become a common occurrence.

Fortunately, there are many areas that you can check to resolve the issue. Continue reading to learn more about common reasons why ATVs backfire and how to fix the issue when it happens.

Why is My ATV Backfiring?

If you want to look at the mechanics of why your ATV is backfiring, you can understand the general principle that is causing this to occur. Backfiring occurs when a minor explosion takes place in the engine’s intake or exhaust as the spark plug ignites the fuel that has escaped the combustion chamber.

ATVs do just backfire sometimes and that’s just part of a combustion engine. There may be no problem at all. If this has become a common occurrence, there may be an issue that needs your attention.

This occurs when there is an imbalance in the fuel to air ratio (among other reasons).

If your ATV is backfiring, you should check a few of the common reasons:

  • The fuel to air mixture is too lean or rich
  • There is an issue with the carburetor
  • The ignition could be faulty
  • The fuel pump could be supplying weak or low pressure

Depending on the cause, there are plentiful solutions to resolve this common occurrence.

Again, it is important to recognize that this issue (backfiring) is relatively common with ATVs. Though, that might not be the most comforting thought when you or your loved one feels the sharp jolt caused by the backfiring vehicle.

When this issue begins to take place more frequently, then you should attempt to narrow down the issue through the process of elimination. Or, you can always have the vehicle inspected by a professional if you are unsure of what could be causing the problem.

Here’s someone with a Raptor 660 having backfiring issues to give you an idea of what this could look like.

Fuel/Air Mixture is Imbalanced

In order for your ATV to work, a specified balance of fuel and air enter into the combustion chamber. Ignited by the spark plug, the engine is given the power that it needs to propel forward.

However, if there is too much fuel (and consequently too little air) being supplied, then it is likely that the excess fuel will leak outside of the chamber.

When this happens, the excess fuel will become ignited by the spark plug- the igniting will just take place outside of where it is supposed to (the combustion chamber).

There is usually a fuel mixture screw located near or on the carb that you can adjust to play with the fuel air ratio a bit until you find something that works.

Then, you will feel the effects of this minor explosion occurring in the wrong location as the sudden pop causes you to startle and your vehicle to jump along with you.

An imbalanced fuel/air mixture can be viewed from a few different angles that typically cause the same result: a backfiring ATV. In this sense, you can see that there is “too much fuel” or “too little air”. What this really means is that the equilibrium that is needed to cause the vehicle to work properly is off, and you will likely experience the resulting backfiring.

However, too much fuel could indicate a fuel leak, and too little air could indicate a clogged component of your vehicle such as the air filter, exhaust, or beyond.

In addition to there being too much fuel, you may also find that there are too little fuel and too much air. In the same sense, the imbalance is what causes the backfiring as the combustion chamber is not filled with the right amount of both “ingredients” simultaneously. To function properly, remember that the engine needs to have both the fuel and air at the proper proportion.

If you find that not enough fuel is mixed in this ratio, then this could indicate another issue.

Primarily, you will likely find that the fuel filter is clogged or the carburetor is packed with “old” oil. Either way, this main reason why your ATV is backfiring can be broken down into a few more reasons that will be shared below. These are some of the root issues that could be causing the fuel/air mixture to be imbalanced in the first place.

Faulty (Clogged) Carburetor

If you are finding that your ATV has begun to backfire rather frequently, then you are going to want to check a few top concerns out.

One reason that your ATV could backfire regularly, especially if your ATV has been sitting in storage for a while, is that the carburetor is clogged.

Though it is tough to distinguish “old” gas from “new” gas just by looking at it, the effects of fuel sitting in your vehicle for long periods can be detrimental to the vehicle’s function.

When your ATV is left sitting at bay for long periods and goes unused, the fuel can begin to degrade and clog up the carburetor. Consequently, a clogged carburetor will not allow the appropriate amount of fresh air into the intake portion of the engine.

With this, the air and fuel ratio will become imbalanced, and you will likely find that your ATV is backfiring regularly.

Backfiring on your ATV due to a faulty or clogged carburetor can be something that begins to occur more and more frequently. In essence, once the degraded oil begins to compile, it is not as likely that you will burn through it without experiencing the jolt of an ATV backfire in the process.

Of course, this can become a safety concern when you begin to experience it regularly.

Not only are you experiencing the physical jolt of your ATV when it backfires- potentially throwing you or your friends and family members off of the vehicle- but a minor explosion is taking place outside of the combustion chamber. This, though not noticeable as you might first picture when the term ‘explosion’ is brought up, is still a danger in the long run.

Here’s a video showing the backfiring issue related to a clogged carb and how to fix it.

I recommend having some Gumout Carb and Choke Cleaner (link to Amazon) handy if you plan on cleaning your carb.

Faulty Ignition/Engine

A faulty ignition/engine is something that you might begin to sound more concerned about, as this can impact serious components of your all-terrain vehicle. However, keep in mind that when this is causing your ATV to backfire, you will at least know the root cause and be able to move on from there.

If your ignition/engine is faulty, then you might have a few issues to work around.

For starters, a faulty ignition could simply mean that you need new spark plugs. In this instance, if your spark plugs are not igniting the fuel inside of the combustion chamber, and instead continue to ignite the fuel in the intake or exhaust, then you will notice your ATV backfiring pretty frequently.

Fortunately, replacing spark plugs is not the end of the world, and these are just small components of the entire ATV.

Next, a faulty ignition could mean that the timing is delayed for the ignition to light the fuel. This means that there could be a slight gap from when the ignition is intended to begin (when the fuel chamber is closed) and when it actually happens (when the fuel chamber is open).

When this occurs, your ATV is not able to properly engage in the way it was designed, and your ATV will backfire quite frequently.

This could also be the case if there are parts of the ignition that are broken or not functioning properly. If the ignition coils, for example, are broken, then the ignition will not be able to operate as it was designed to do. Then, your ATV is at a high risk of backfiring.

Along these lines, a faulty engine could mean that there is something wrong like a leak, bend, or break in the components of the engine. Consider if there is a crack in your muffler or exhaust, for example.

If this is the case, then the air and fuel flow will not be consistent, and you will have variable ranges of the two “ingredients” as they enter the combustion chamber. This means that your ATV is, again, at risk of backfiring.

Here’s a quick video showing how to replace an ignition on an ATV to give you an idea of what’s involved.

Weak or Low Pressure from the Fuel Pump

Again, when you are looking at the issues with your ATV backfiring, it is likely because there was not enough (or too much) fuel being allowed into the engine either through the intake or in the exhaust.

This means that the “leftover” fuel is being ignited in the exhaust, or the fuel that is being blocked by “too much air” is being lit in the intake portion.

Either way, the balance is off for the combustion chamber meaning the unsteady flow results in a backup of the “ingredients” and, consequently, the resulting backfire. As the flow of the fuel and air is imbalanced, the vehicle is not capable of performing how it was intended to perform.

One reason that this could occur is the weak or low pressure from the fuel pump.

Though there are many reasons that the engine could be receiving too much or too little fuel, a fuel pump that is too weak or low pressure could mean that not enough fuel is being supplied in the first place. While you are attempting to fill up your ATV with fuel, you could be supplying a smaller portion than you are assuming you are.

This could mean that there is not enough fuel in the first place, thus, the imbalance would be due to insufficient fuel being supplied through the intake.

If this is the reason, then you might be fortunate as you will simply have to monitor how much fuel you are putting into your vehicle and ensure that there are no leaks that could otherwise be causing this issue.

In this case, you would be able to narrow down whether or not the fuel pump was the source of the issue, or if there were other reasons why the fuel is not making its way to the combustion chamber as intended.

Here’s a quick video showing how to check the fuel flow so you can try to rule that out as a problem.

How to Fix a Backfiring ATV

Determining how to resolve your backfiring issue with your ATV will take the process of elimination. If you are familiar with the components of your ATV, then you might be able to check a few of these options yourself. Otherwise, you can always bring your vehicle to a professional for an inspection and repairs.

Listed above are some of the common reasons that an ATV backfires including the imbalance of fuel/air mixture that is perpetuated by issues with the carburetor, ignition, engine, and fuel pump.

Fixing these issues means finding the root of the issue and addressing the particular need. This could include a wide array of actions, so pay attention to the vehicle and how it is operating.

If you are experiencing one of the above (or similar) issues, here are a few suggestions for resolving your ATV’s backfiring issues:

Observe and change the air and fuel filters

If the primary reason that your ATV backfires has to do with the air fuel mixture being slightly off, then it is imperative that your fuel and air filters are working appropriately. This means that they should be blocking out any particles such as dirt and mud that could otherwise clog them up.

Similar to driving another automobile, these should be regularly changed. However, some could argue that this is even more important when operating your ATV considering the various terrain that you could be driving on.

If your filters seem like they could be changed, then they probably could be. This simple fix will not cost a very high amount, but it will definitely save you and your ATV in the long run.

Not all ATVs are set up the same, but here’s an example video showing how to replace an ATV air filter.

Clean your fuel injector and carburetor

Another component for the proper injection of fuel and air is the mechanical aspects of the fuel injector and carburetor. As mentioned above, these can become clogged or faulty. If they are, then they will not be able to properly release the amount of fuel/air that is needed to run your ATV.

Consequently, remaining fuel will get left in the intake or exhaust and cause the ATV to backfire.

As a simple solution to this, you can be sure to clean your fuel injector and carburetor. You might need to purchase a solution that will clean these out- though this is still an easier feat than damaging yourself or your vehicle.

I recommend having some Gumout Carb and Choke Cleaner (link to Amazon) handy if you plan on cleaning your carb.

Here’s a quick video showing a work around way to clean the fuel injectors on an ATV.

Use high-quality fuel

It might seem somewhat obvious, but the type of fuel that you use on your vehicle affects its overall performance. If you are using low-quality or “old” gas in your ATV, then you can expect to experience a low-quality ATV performance including backfiring.

Instead of allowing your ATV to backfire due to buildup or leaked fuel, be sure to choose a high-quality fuel that will help your vehicle (and its engine and other associated parts) to perform at their highest level.

The better you treat your ATV, the better you can expect it to treat you in terms of a quality experience (and no backfiring).

Use appropriate settings on your throttle

The throttle of the ATV is what releases the fuel into the engine and thus allows you to accelerate forward. Whether you have a thumb throttle or a twist throttle, you could be operating at a setting that is inappropriately providing too much fuel to your engine while you are sitting still (idling) or while you are in full swing.

To adjust the settings of your throttle, you will need to review the particular settings that are recommended for your vehicle. Either you can find these in your ATV’s operational guide, or you can do a quick search to see what is appropriate given the varying terrains, speeds, and your personal use of the throttle (and vehicle).

Hire a professional

Though you might want to learn about your ATV- and perhaps you enjoy the hands-on work that comes with taking care of this type of vehicle- it is best to leave the job to a professional if you do not know what you are doing.

It is better to pay a bit out of pocket for a professional to run a few diagnostics than for you to cause (greater) harm to your vehicle.

There are several professional options available to you depending on your area. While some will have access to shops that can look at and review the mechanical and other issues going on with your ATV, this might not be the same for all.

Be sure to check with any local recommendations as many people who work contracts for ATVs- or those who consistently use them- likely have their set client list and expectations for professional practice.

Word of mouth can be incredibly helpful when searching for the right professional in your area, so try to be comfortable with meeting diverse people who are different (and yet have the same ATV interest) as you.

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