How to Diagnose and Fix a Backfiring ATV?

Is your ATV engine make an unusual sound? Like a popping sound with little flames coming out from the exhaust system. You might think, What causes popping in the exhaust? Also, it makes ATVs kick forward a little bit. Sometimes it can shut off your ATV suddenly and want to restart it again. This situation calls ATV backfire.

What causes backfire on an ATV? Let’s talk about it. Every petrol or diesel engine can backfire because it has an internal combustion engine. Mostly it can be expected, but if it happens constantly and affects your daily work, you should fix it as soon as possible. Every engine can backfire, but it can damage your ATV if it happens constantly. It happens when the engine gets unbalanced air and fuel mixture. Today, I’m going to cover all scenarios about this situation.

What is ATV backfire means and why it happening?

Usually, Atv backfires when the engine gets more fuel than air to make a perfect mixture to perform the engine cycle. It’s called fuel rich situation. Also, when the engine gets less fuel than air, it can backfire. This situation calls a lean fuel situation. Engines work with a little explosion in the combustion chamber, which should happen. It needs a correct and balanced fuel mixture and engine environment to keep this explosion smoothly and efficiently.

I researched the fuel and air mixture ratio for work ATV engines. I found it should be in 14.7:1 to work generally. (14.7 units of air for 1 unit of fuel) So when the mixture ratio gets rich or lean with air or fuel, the ATV engine can backfire. There can be other reasons for your ATV to backfire. The Atv engine needs fuel and air to work. After the mixture gets into the combustion chamber, it ignites with the spark from the spark plug. This explosion should happen in the chamber, but in our situation, it can happen on the intake or exhaust valve sides.

Primarily your ATV will work fine, but this is not good. Four-wheeler backfiring on acceleration and deacceleration is another situation. While you rapidly accelerate or deaccelerate your ATV, it changes the engine performance. The accelerator works as an opener to the air valve and takes air to the combustion chamber. If your air intake is clogged, it’s not can take the needed amount of air to mix with the fuel.

It creates a rich fuel situation and makes backfires. In cold mornings, ATVs backfire when trying to start.

Starting an ATV engine gives fuel and air to the chamber, but the air and fuel mixture do not get the ratio to perform the start. That’s why it backfires for a few seconds when you try to start the ATV. Like when starting, when you shut off the ATV, it can backfire, Because that unburned fuel and air mixture can ignite with the heat of exhaust pipes.

What can cause ATVs to backfire?

• Rich or lean fuel and air mixture : Does backfire mean rich or lean? Yes, and this is the common reason. When the engine gets a rich fuel mixture to the chamber, it will not burn all fuel. That extra fuel comes out with smoke. After entering the exhaust valve, that fuel can burn on the muffler. In the second, it makes backfired with a loud noise. In rare cases, It can damage your exhaust system.
• Clogged air filter : your air filter can get clogged easily. When we operate ATVs in dirt, mud, and sand, things or particles can clog the air filter. Also, I have an experience with squirrels and rats. When I park my ATV for a few weeks, these animals can make their nests. They make nests on it, and it can block the air filter. So keep an eye on this point for sure.
• Fuel pump going bad : your ATV fuel pump can clog or not work correctly. It should maintain the fuel pressure to perform the engine softly. If the fuel pump cannot give pressure, it can be a reason for the ATV to backfire.
• Clogged fuel filter : fuel filter can be clogged by particles of dirt on the fuel. Make sure to use quality fuel for the ATV. Otherwise, it can harm the engine. You can prevent it filter fuel before adding it to the ATV.
• Carburetor issue : ATV carburetors can effect by small dirt or particles in the fuel. I talked about it on the above point. If that particle is stuck in jets, it blocks the fuel to the chamber. Also, when you leave your ATV for a long time, the fuel on the tank can be a little thick because the fuel is not mixing or shaking. It can clog the carburetor jets.
• Engine timing changed : engines have a cycle to make the power. The engine has a timing to open intakes, do compression, ignite and make an explosion to push the piston and open exhausts. This process needs a sync timing with cylinder heads. If this time gets delayed, it can cause fuel not to burn totally inside the chamber. After it, fuel gets out from the exhaust valve, burns inside, and backfires.
• An exhaust system or muffler change : if you changed your exhaust system recently, it can be a reason. Because it can affect engine default states, make sure if you upgrade your exhaust, tune up your engine according to the new exhaust system.
• Damage happens on the exhaust system : ATV can slip, turn over, flip or crash. When it happens, it can damage the exhaust pipes on the ATV. Exhaust pipes can bend, lose the connection, or be a hole. Check the exhaust pipes for damages, as I mentioned above.
• Fouled Spark plug or other engine faults : spark plug can get stuck, dirt, or water. When it blocks the ignition process, it can be a reason for the ATV to backfire. Also, if it’s not enough power to perform ignition, there can be a reason. Engine time change, faulty ignition coils, or faulty wire connection can be a reason.

How do fixing ATVs backfire?

1. Clean air filter : The air filter can reuse again after cleaning. If you see it, you can identify whether it wants to be changed or not. The air filter can clean with an air pressure gun to remove dust and particles.
2. Clean the fuel injectors : Can a bad fuel injector cause a backfire? Of course. You can use a fuel injector cleaner for this. The cleaner liquid can directly add to the fuel tank.
3. Add fuel stabilizer : if you park ATV for months, fuel will degrade on the tank. To prevent it, you can use a fuel stabilizer. It will keep your tank clean for a few months.
4. Clean the spark plug : over time, spark plugs get corrosion, blocking the ignition process. You can easily remove the spark plug with a tool that looks like a hexagon. Check and clean the sparkplug head with sandpaper and brush.
5. Always use a filter before adding fuel to ATV : I know you will agree with me. Fuels come with some dirt sometimes, so always use quality fuels, or you can manually filter it because adding to the tank.
6. Clean carburetor jets : this point is not easy like others because it needs to be inside the engine. I hope you can hire a professional for this step.
7. Adjust throttle settings : in this process; you should do research according to your ATV brand, what is the best throttle setting for your machine. With a little screwdriver, you can increase or decrease the fuel and air supply to the engine.
8. Hire a professional : if you are not comfortable troubleshooting, you can get help from a professional about ATVs. Sometimes it can save some bucks because unexpected accidents can happen on our hands.

The Bottom Line

I hope now you have the complete picture of the ATV backfire problem. What causes ATVs to backfire? Why does it happen? Does backfire mean rich or lean? And I pointed out all things you want to diagnose the problem. You can follow the step by step and fix it at home quickly. Last, keep your ATV clean as much as you can. Happy riding, manual riders!