How to Fix ATV Stalling at Idle
There are many reasons you may experience an ATV stalling at idle.
What You May Be Experiencing When Your ATV Won’t Stay Running
The two most common and direct symptoms are your ATV stopping as soon as you let off the throttle and an engine that will only run a few seconds while idling. You might also notice that your ATV is a little harder to start or that your ATV idles but won’t rev up.
Idle speed
Your ATV was designed with an idle speed adjustment that keeps the throttle just slightly open even at idle, so whether you are applying throttle or not, your vehicle is getting enough gas to keep running.
Adjust the idle screw to turn the speed up a bit.
Carburetor Issues
Your carburetor may be to blame for ATV stalling.
Air to Fuel Ratio
Check the fuel mix first. It is the most common carburetor issue to cause idling problems. The mix should be 14.7:1. It is set this way at the factory, but wear and tear, aftermarket upgrades, and repairs done without correctly adjusting the fuel mix can all throw it off.
A fuel mix screw controls the mix. You’ll need to check your owner’s manual for the exact instructions.
Dirty Pilot Jet
The pilot jet supplies the gas. If it’s not sending out as much gas as it should, it’ll cause the biggest problem when you’re at idle. Old gas can gum up your pilot jet and is one of the leading causes of idle issues.
Remove the jet, clean it, and make sure you aren’t using old or contaminated gas.
Intake Boot
If your intake boot is cracked or not seated correctly, it will ruin your air to fuel ratio. There are a lot of cheap DIY fixes for this online, but you can go the high quality route and purchase a new intake boot.
Dirty Carburetor
The carburetor itself can be dirty and clogged, and when it is, fuel can’t pass through there like it should. You are particularly likely to have this problem if you let your ATV sit for long periods without being properly stored, use old gas, or don’t have an air filter.
You may be able to clean the carburetor outside. If not, you may have to disassemble it and clean the inside.
Faulty Petcock
If your petcock is getting old and stiff and refuses to move as much as it was designed to do, you may be getting too little gas to idle.
You can replace your diaphragm, replace your petcock, or bypass the petcock altogether.
Dirty Air Filter
If your air filter is dirty, it will restrict air flow and cause your engine to run rich. You’ll be able to tell this is happening because your ATV will blow black smoke, have black plugs, bog, and stall.
Check your air filter and all passageways that carry that air into your vehicle for clogs, holes, and kinks. If your filter is dirty (which is usually the problem), replace the filter and make sure to use the recommended filter oil. If you have passageway issues, you’ll have to clean, unkink, or repair those.
Bad Gas
Old or contaminated gas reduces your ATV’s power and can clog up your carburetor. Water can get in your gas if the cap wasn’t on tight, your ATV got submerged, you store your ATV outside, or you bogged it in mud. You’ll have to clean your carburetor jets, start storing your gas properly, use fuel stabilizer, or get that water of your gas tank and carburetor.
The Rest
Fuel Filter and Lines
Your carburetor can’t do its job if it isn’t getting enough gas. When your ATV only runs with throttle, make sure your filter is clean. If it hasn’t been cleaned as it should or you have contaminated gas, it could be dirty and restrict fuel flow. Replace the filter and make sure your gas is clean and fresh. Also check that your fuel lines aren’t clogged or kinked.
Fuel Injectors
These nozzles use high pressure to do their jobs, so the holes in them are very small. It’s very easy for them to get clogged with the carbon left behind from combustion. When they do, they can cause an ATV stalling problem.
You might be able to clear the clog with a fuel injector cleaning additive. If that doesn’t work, you’ll have to take your ATV to a mechanic.
Fuel Vent
Your ATV has a fuel venting system that allows air to enter the tank as the fuel level drops. Depending on your model, the vent may be located in different places, but regardless of where it is, if it gets blocked or malfunctions, you end up with a vacuum in your gas tank and the carb and fuel pump won’t be able to get the fuel out of your tank.
Test if this is the problem by loosening the cap. If it temporarily fixes the problem, then you have a vent issue.
Fuel Filter and Lines
Similarly to vent problems, if you have an issue in your fuel lines or your fuel filter is bad, you’ll have fuel flow issues and ATV stalling at idle. Check your filter first. Then check your fuel lines.
Etc
Some Polaris ATVs use an ETC switch or engine throttle control. If the two metal connectors inside the switch touch, it will cause your ATV to stop at idle. Your owner’s manual will tell you the exact specifications to correct this issue.
