Was your ATV running fine just recently but suddenly stopped working? When this happens, there are a few usual suspects to look into.
This post explains how to troubleshoot and fix the most common reasons when an ATV stops running and no longer wants to start for no apparent reason.
The ATV Is Out of Fuel
While this might seem obvious to some, it must be on this list. You’d be surprised how often people think there is gas left in the tank, but at the end of the day, all the bike needs is more fuel.
Some fuel tanks are built so that even if you can hear fuel slushing around inside the tank when you rock your ATV from side to side, the fuel level might be adequate to get fuel to the carburetor.
After refueling, if your ATV has an electrical fuel pump, cycle the key to the on position three times for 5 seconds each to prime the fuel lines before starting the engine.
Kinked or Clogged Fuel Line
Fuel lines are bendy, and if you’ve been working on your quad, it’s easy to accidentally leave one in a bent or kinked position where fuel won’t flow through.
Also, if the fuel you use has become contaminated by dirt or corrosion from the gas tank, it might have plugged the fuel lines. Another cause of clogged fuel lines is using old fuel that may gum up and leave deposits inside the fuel lines and carburetor.
Plugged Gas Tank Vent
The gas tank has a vent allowing air into the tank as you burn off the gas. If the vent fails or becomes clogged with mud or debris, a vacuum will form inside the tank, and the engine will no longer receive fuel.
Some ATVs have a vented gas cap, while others have a separate vent with a small tube attached.
One way to test if that’s your issue is to release the gas cap slightly to let air in and see if the ATV will run.
Inspect the vent, clean it if it is dirty, or replace damaged parts to restore the gas tank venting.
Water Present in the Fuel
Water in the fuel will cause the engine to stop as soon as it enters the carburetor. There are several ways fuel gets contaminated by water, but the most common is through a leaky gas cap or buying fuel from a gas station with a leaking tank.
If there is only a tiny amount of fuel, try using a water remover additive. However, the best and safest alternative is to drain the water-contaminated fuel and replace it with fresh fuel.
Old or Non-recommended Fuel
Fuel can deteriorate over time through evaporation, disrupting its composition. When this aged fuel enters the carburetor, it can lead to gumming up and impaired functionality. This is how to know if the gas has gone bad.
Similar problems can occur if you’re not using the correct fuel grade for your ATV.
Replace the old fuel with fresh, recommended fuel. Additionally, use an engine cleaner additive such as Seafoam in a couple of tanks to clean out the carburetor.
In severe cases, the carburetor might need a complete cleanse and rebuild.
Faulty or Corroded Kill Switch
The main job of the kill switch is to start the ATV immediately in an emergency; it is typically not used daily to stop the engine.
Kill switches sit in an exposed position and are prone to corroding over time, causing them to short out internally. When this happens, the ATV will no longer run until you replace the switch.
If you have a multimeter, you can test if the switch works properly by testing for continuity in the Off and ON positions.
Fouled or Defective Spark Plug
Spark plugs may foul up or go bad for no apparent reason.
Remove the spark plug to see if it seems contaminated or corroded. A healthy spark plus should look like in the picture below, with a milky brown color.
Also, ensure the spark plug gap meets the spec and use a plug with the proper heat range.
Use a spark plug gap tool to set the gap according to specs, or replace the plug if you suspect it’s gone bad.
Damaged or Worn Spark Plug Wires
Inspect the spark plug wires and look for signs of damage or cracks from old age.
Bad spark plug wires will prevent the spark plug from creating a spark and must be replaced.
Loose Ignition Connections
If connections in the ignition system wires rattle loose or become corroded, the ATV will no longer receive a spark, and the engine will not run.
Check all connections, clean them if corroded, and ensure they are tightened.
Also, check the fuse box for blown fuses, and don’t forget the main fuse, typically located separately from the fuse box.
Low Battery Voltage
Excessive winching or repeated starts and stops might drain the battery, so it no longer has the power to support vehicle operation.
Some ATVs will run fine with a bad battery, while on others, a discharged battery may cause the engine to stall or run irregularly.
To fix the issue, recharge the battery using an external battery charger.
Clogged Air Filter
If the air filter has become too dirty or the intake is clogged, the engine will no longer receive the air it needs to run.
Air filters should be inspected daily to ensure they are correctly seated and not dust-covered. If the filter seems dirty, clean it or replace it according to manufacturer recommendations.
Generally, sponge-style filters are serviceable and can be cleaned and re-oiled, while paper filters need replacing.
When an engine overheats, it might shut down or go into limp mode to protect it from damage.
If the temp warning light turns on in your instrument panel or the ATV displays any other signs of overheating, you must fix the issue before continuing riding.
Overheating problems can often be traced back to a dirty radiator screen or core. Remove the screen to clean it, and use a garden hose to rinse off the radiator core.
Do not direct the nozzle of a pressure washer to the radiator, as it will damage the aluminum radiator fins.
If you cannot identify and fix the cause of your overheating issue, take the ATV to your dealer.
Unfortunately, many other things could cause an ATV to stop working.
Mechanical engine failure and electrical issues like bad switches or wiring or fuel injector problems, to name a few. However, those matters are generally better for the dealer to figure out.