This guide will help you troubleshoot the most common causes for an ATV that won’t start. Some issues are easy to fix at home, while others require assistance from a mechanic.
These are the main reasons why an ATV will not start:
- The ATV is not getting a spark or only gets a weak spark
- The ATV is not getting fuel
- The ATV is not getting enough air
- The battery is defective or low on charge
- The kill switch is bad or corroded
To identify what is causing your ATV’s starting issues, you must notice how it behaves when you attempt to start it. Choose the topic below that best describes your vehicle’s behavior to begin troubleshooting.
Related: Guide: How to Start an ATV That Has Been Sitting
The ATV Won’t Start – The Engine Is Not Turning Over
If your ATV doesn’t crank when you’re trying to start it, there are a few basic things to consider.
1. Ensure the kill switch/run switch is in the “ON” or “RUN” position
You’d be surprised how often the solution to an ATV that won’t start is forgetting to turn on the kill switch.
Also, if your ATV has a tether pull-cord style kill switch, ensure it is properly connected.
2. Make Sure the ATV Is in “Park” or Neutral
As a safety precaution, many ATVs are designed not to start when in gear.
3. Make Sure the Battery Is Charged
The battery should read 12,6 – 12,8V. Use a multimeter or a voltmeter to check the voltage.
If the voltage drops too low, the battery won’t have enough charge to start the bike.
Charge the battery or replace it if it’s dead. An easy way to test your battery is by checking the voltage drop with a multimeter as you try starting the bike. If your battery, when fully charged, drops below 11.5 volts while cranking the starter, it needs to be replaced.
4. Check the Main Fuse
Most ATVs have a main fuse; your user manual will help you locate it.
If your battery is charged, but you still get nothing when turning the key, you may have a blown main fuse. Replace it with the right size fuse and try starting again.
5. Make Sure the Solenoid Is Getting Power
The solenoid works as a switch that sends a high current to your starter when you push the start button or turn the key. For it to work, you need to ensure it gets power from the battery.
The solenoid should make an audible “clicking” sound each time you hit the starter. If it does, you know it is getting power, and the problem is likely with the solenoid itself or the starter. Solenoid and starter issues will be covered later in the post.
If you do NOT hear a clicking sound, you can use a multimeter or voltmeter to verify that the solenoid is, in fact, not getting power.
- Put your multimeter to DC Voltage.
- The red lead goes to the solenoid’s battery side (red).
- The black lead goes to ground.
- You should get a voltage reading of 12V or more.
If you don’t get a reading, trace the wiring back to your battery to identify where the connection is broken. Look for loose or corroded terminals or shorts from damaged cables.
The ATV Won’t Start but Turns Over
A gasoline engine needs three essential components to start and run:
- Gasoline
- Spark
- Air (compressed)
1. Check if the ATV Is Getting Fuel
- Locate your spark plug. You may need to remove a few plastic covers to find it.
- Remove the spark plug wire (on a carbureted ATV) or the ignition coil (on a fuel-injected ATV) from the spark plug.
- Remove the spark plug from the cylinder head using a spark-plug removal tool.
- If the plug it’s wet, you know the bike is getting fuel.
If the plug is dry, the bike is not getting fuel, and you need to continue the troubleshooting as described below.
2. Check for Spark
- Install the spark plug back into the cylinder head.
- Connect an inline spark tester between the spark plug and the spark-plug wire/ignition coil. You can get one for cheap at most auto supply stores.
- Make sure the run switch is in the “ON” position.
- Please keep your hands clear of the test tool and the area around it.
- Push the starter button.
- The test light on the spark-tester will light up if there is a spark.
Alternative method: If you don’t have a spark tester tool, you can do a visual test to check for a spark. Please note that this method may cause electric shock if done incorrectly.
- Remove the spark plug from the cylinder head and connect it to the spark-plug wire or ignition coil.
- Grab the plug wire and hold the plug about 1/8th of an inch away from the cylinder head. Make sure you are only touching the rubber and not any metal parts.
- Activate the starter.
- You should see repetitive bright blue spark arching from the spark plug to the cylinder head as the motor turns.
You will find the proper steps for troubleshooting an ATV that is not getting a spark further down this post.
The ATV Is Not Getting Fuel
If the spark plug is still dry after cranking the engine for a few seconds, you know that fuel, for some reason, is not getting to the cylinder.
Often, the issue is either with the fuel pump or a clog in the fuel supply line between the gas tank and the carburetor.
Old or unstabilized gas tends to gum up over time and may create a clog. Dirt and debris getting inside the tank is another common culprit for a clogged-up fuel supply.
The easiest way to identify the cause is through a process of elimination.
If you find contamination, such as dirt or gummed-up fuel at one spot, the whole system is likely dirty and needs a complete clean for the best result.
The steps differ slightly depending on whether your ATV has EFI (electronic fuel injection) or a traditional carburetor system.
Ensure the Gas Cap Vent Is Not Clogged
ATVs have a vented gas cap or a separate gas tank vent tube. Make sure neither is clogged and allows air to flow freely.
Fuel must be replaced with air as it gets pumped out and used. If the vent is blocked, it may prevent the fuel pump from pumping fuel out of the tank.
When a Carbureted ATV Is Not Getting Fuel
Older ATVs and some cheaper models are still designed with a traditional carburetor fuel system.
1. Make Sure the Fuel Shut-off Valve Is in the “On” Position
There should be a shut-off valve at the lowest part of the fuel tank. Make sure it is turned on.
2. Check if the Carburetor Is Getting Fuel or Not
This step will help you narrow down the possible causes of why fuel is not reaching the cylinder.
With the fuel valve open, disconnect the fuel line from the fuel inlet of the carburetor. Turn over the engine to see if gas is coming through the fuel line.
If it is very little or no fuel coming from the fuel line, you likely have either:
- A clogged up or faulty shut-off valve.
- A clogged-up fuel filter.
- A fuel-pump problem.
- A clogged gas cap or gas tank vent.
If there is a steady or pulsating stream of fuel, you know that
- The fuel pump is ok.
- Fuel flows all the way undisrupted from the tank to the carb.
- The problem is likely a dirty carburetor.
Continue your troubleshooting based on the results of this initial test.
3. Check if the Shut-off Valve Screen Is Clogged Up
Fuel exits the fuel tank through a shut-off valve at the lowest part of the tank. Inside this valve, a mesh screen is supposed to stop dirt and debris from entering the fuel lines.
Disconnect the fuel line from the valve to see if gas comes through. If fuel does not flow freely, you must remove the valve to clean it.
All fuel left in the tank will drain as you remove the valve. Use a bucket to collect the fuel.
Use carb cleaner, fresh gas, and a toothbrush to clean the valve and mesh screen. Pour fresh gas into the tank to flush out any remaining gummed-up old fuel or debris before installing the valve.
If the gas in the tank is old or contaminated, you should not put it back in the tank after cleaning the valve.
4. Check if the Fuel Filter Is Clogged Up
Not all ATVs have serviceable fuel filters, but some do. Trace the fuel line from the fuel tank to the carburetor. Look for a cylindrical canister installed in line anywhere on the fuel line.
Fuel filters are cheap and easy to replace, so it’s worth doing if you suspect that something disrupts fuel flow.
5. Troubleshoot a Fuel Pump That Is Not Working
ATVs with traditional carburetors usually have a vacuum-operated fuel pump. They are run by vacuum/pressure pulses created in the crankcase. The negative pressure pulls fuel in, while positive pressure pushes fuel out.
- Locate the pump by tracing the line coming from the gas tank.
- There are three rubber hoses attached to the pump.
- One is fuel coming from the gas tank.
- One is fuel exiting the pump and to the carburetor.
- One is the pulse line (air), usually marked with a “P.”
- Disconnect the inlet fuel line and position it lower than the fuel tank to make sure gas flows undisrupted from the gas tank.
- Reconnect the inlet fuel line.
- Inspect the vacuum line for any damage or cracking and replace it if necessary. Leaks will prevent the pump from working correctly.
- Ensure the pulse line is connected correctly at the pump and by the crankcase.
- Make sure the engine oil isn’t overfilled. This may cause some oil to get trapped in the pulse line, obstructing airflow.
- Also, inspect the fuel lines going from the fuel tank to the fuel pump. If there are any signs of weather cracking, replace the line. Cracks in the fuel line may cause the pump to suck false air into the tube instead of gas.
- Connect a vacuum gauge if you have one. The gauge should register the pulses. If no vacuum is detected, the engine might have internal issues, such as a stuck valve. Addressing these problems typically requires a mechanic’s expertise.
You may need to replace the pump if it is still not working.
Alternatively, you can pull it apart to give it proper cleaning and a rebuild. Inside there are check valves that may get stuck if dirt enters the pump. There is also a rubber diaphragm that may stretch or crack over time.
6. Test a Vacuum-Operated Shut-off Valve (Petcock Valve)
Some ATVs have a vacuum-operated shut-off valve designed to open only when the engine is running.
Identify the vacuum line that goes to one of the inlet ports. Disconnect the line and draw a vacuum to the disconnected port. The valve should now open and allow fuel to flow.
Inspect the vacuum line to ensure it is correctly connected at both ends and has no cracks that will draw false air.
If you suspect the valve is not working, put it in “prime,” which will override the vacuum-operated valve. This will tell you if the valve is working or not.
7. Clean the Carburetor
Old unstabilized fuel and debris from the gas tank may completely gum up the carburetor or block the jets, so the engine is not getting any fuel.
I recommend using a product like Seafoam or similar to see if it will dissolve the gummed-up fuel before embarking on a more thorough cleanse. Leave the choke wide open to allow maximum flow.
Click here link for instructions.
If Seafoam doesn’t work, your best bet will be to remove and disassemble the carb to clean it properly. This job may not be for everyone. Consider asking a mechanic if disassembling the carb seems intimidating.
- Start by draining the carburetor. There should be a drain screw at the bottom of your carb bowl.
- Disconnect the carb from the ATV and move it over to a tidy workbench. You do not want to be missing any parts when reassembling the carb.
- Disassemble the carb. Take photos as you remove parts to keep track of where things go.
- Use carb cleaner and a toothbrush to clean as much as you can.
- Use an air compressor with a nozzle to clean all the small passages inside the carb.
- Remove both the main jet and the pilot jet. Make sure you can see the light coming through it. If you cannot clean the jet, it’s best to replace it. Ensure the float assembly is not stuck and pull up the float needle.
- Reassemble the carb and install it on the ATV.
- You will also need to address the cause of your dirty carburetor, or it will clog up the next time you ride. Drain or siphon all of the old fuel out of the gas tank. Flush the tank with some fresh gas. Replace any fuel filters, as well, as they are likely just as dirty as the carb.
- Consider adding a cleaner product such as “Seafoam” to your first tank of gas after the cleanse. This will dissolve any gummed-up fuel still trapped in the system. Follow the manufacturer’s instructions, depending on which cleaner product you use.
Check out this guide for more detailed instructions on disassembling and cleaning a carburetor.
Related: Chinese ATV Won’t Start – Troubleshooting Guide
When a Fuel Injected ATV Is Not Getting Fuel
Fuel-injected engines, called EFI (Electronic Fuel Injection), use an electronic pump to feed pressurized fuel through fuel injectors and into the engine.
Troubleshooting a fuel-injected ATV is a bit trickier than carbureted ATVs, but it’s possible:
1. Make Sure the Internal Fuel Filter Is Not Clogged
Most fuel-injected ATVs do not have a serviceable fuel filter.
Instead, they have a non-serviceable screen or a sump filter inside the gas tank. Note that some EFI ATVs also have an inline external fuel filter.
The screen or filter is one component of the fuel pump assembly inside the tank. These filters are not meant to be serviced but may still clog up.
You need to remove the whole fuel pump assembly to access the filter.
Begin by removing any plastic covers to access the top of your gas tank. A large plastic locking ring connects the fuel filter assembly to the fuel tank. You may need a set of large pliers to remove the ring as they tend to bind.
Be careful not to damage fragile plastic components as you remove the pump assembly.
The filter will be at the very bottom of the assembly. You will generally need to replace the whole assembly to replace the filter.
To save money, consider looking up a suitable replacement filter online.
2. How to Troubleshoot an EFI Fuel Pump
Electric fuel pumps tend to fail for no apparent reason from time to time. Before they break entirely, they may gradually weaken due to wear.
A worn fuel pump may not create sufficient fuel pressure for the injection system to mist the fuel properly, which may prevent the ATV from starting. Aftermarket fuel pumps are available for most ATVs, but replacing them is not for everyone.
Also, you have possible fuel pressure regulator issues or rotten o-ring seals.
The best way to test an electric fuel pump is by measuring the fuel pressure at the fuel rail. This will, however, require a specialist tool that the average home mechanic does not have.
A clogged fuel filter or lines may also cause too low fuel pressure.
Before replacing the fuel pump assembly, it’s worth ensuring the bike is charging correctly, as a low voltage will negatively impact fuel pump performance.
3. How to Troubleshoot Fuel Injector Problems
Modern EFI ATVs may provide an error code indicating fuel injector issues. Troubleshooting fuel injector problems, however, is a task that often gives even seasoned mechanics a headache. I recommend you save this job for a dealer.
The ATV Is Not Getting a Spark
Here are a few things to try out if your ATV is not
