It can be pretty frustrating when your quad won’t start and all you want to do is hit the trails. There are some pretty simple checks you can do to see where your problem is. A lot of times there’s something simple you can do to fix it and get back out riding. Other times, there’s some bigger issues keeping your engine from starting up.
The first things to check is if you’re getting gas and spark to your engine. Most of the problems with an ATV not starting have to do with either not enough fuel getting to the engine, or the engine is not getting enough spark.
Is The Battery Good?
The easiest fix for an electrical problem is changing out the battery, so lets make sure the battery is good before we go any further. You’ll need a multi-meter set to voltage to check your battery.
Place the leads of the multi-meter on the positive and negative terminals of the battery. You should see a reading above 12v on the multi-meter, if you’re getting less than that, you should try charging the battery. Check out How To Charge An ATV Battery, for a more in depth guide on how to do that.
If you’re battery doesn’t hold above 12v after a nice long charge, you may need to replace the battery. If you’re battery isn’t the problem, maybe something else in the electrical system is preventing the quad from starting. Time to check for spark.
Is The ATV Getting Spark?
If your engine’s not getting any spark, or getting weak spark, it won’t start at all. The engine will turn over, but will never be able to ignite the fuel and get running. Don’t worry, there’s a quick and easy way to check for spark.
Just take the spark plug out of the engine and plug it back into the spark plug wire. Put the spark plug on the cylinder or something that will ground it. Make sure the spark plug electrodes will be close enough to something grounded. Try starting the engine, if everything’s working right, you should see some spark coming out of the spark plug, jumping to whatever grounded part it’s touching.
The first thing you should try, is replacing the spark plug. They’re cheap and usually the cause of getting no spark. Make sure you get the right spark plug for your engine and that it’s gapped correctly.
If you’re still not getting any spark, you have a bigger problem. If it’s not you’re only problem, it’s still one that needs to be fixed before you can get the quad running. Check out this How To Check For Spark On An ATV, Reasons For No Spark article to get more in depth steps on what to check within your electrical system for why you’re not getting spark. I also explain what you’ll need to do to fix the problem.
Is The ATV Getting Fuel?
There could be a number of reasons the engine isn’t getting enough fuel to start and stay running. The most common reasons have to do with the fuel pump or the carburetor. If you have a fuel injected motor, you may just need to clean the injectors to get it running smoothly again.
To quickly check for gas flow, remove the fuel line from the carb or injectors and place over some sort of container to catch the gas. The gas should flow freely, if it does not, try blowing out the fuel lines and inspect the fuel pump and filter. If gas does flow freely, your problem is further down in the carb or injectors.
If you have a fuel pump issue, it will most likely be the diaphragms inside the fuel pump or the filter is too clogged to allow fuel to flow freely to the engine. If you have a carburetor, the most common fix is replacing the needle valve and seat.
If you notice your spark plug is dry after trying to start the engine, that is a good indicator that you’re not getting fuel to the engine. Start by spraying some carb cleaner or ether into the carb or injectors and then try to start up the engine. This could help you start to narrow down the issue.
For a more in depth, step by step guide on how to troubleshoot fuel issues on your ATV, check out my ATV Not Getting Fuel: Common Reasons And How To Fix article. In that article I go through the most common reasons your engine may not be getting fuel and how to fix the problem.
Is There Enough Air Flow?
This one’s real simple to check, but also one of the most important. If your engine isn’t getting enough air to mix with the fuel in the combustion chamber, it won’t run properly and might not even start up.
Make sure the air filter is cleaned out, and there are no obstructions blocking the air box intake. You may need to replace the air filter all together, it’s a good idea to do that once in a while anyways. But if the filter isn’t that old, you might get away with just cleaning it out real good.
For a more in depth look on how to clean your air filter, check out my How To Clean The Air Filter On An ATV article. In that article I go through step by step on how to clean your air filter to make sure your engine is getting the right air flow it needs to stay running.
Aside from checking the air intake, also check the exhaust. Your ATV needs good airflow into the engine, as well as out. This is pretty rare that your exhaust will get blocked up, but it can happen. I’ve seen an exhaust get clogged up with mud and the engine wouldn’t start because of it.
Is The Engine Getting Compression?
If your engine isn’t getting enough compression, it won’t be able to pull fuel into the cylinder and stay running. The inside of your engine has some moving parts that need to be sealed up tight in order to work properly.
The most common reasons you’re not getting enough compression is a worn out or leaking head gasket or a blown piston ring. Sometimes, if dirt has been getting into the engine through the air intake, you could have scarring on the inside of the cylinder walls. I hope that’s not your case, but it will cause a loss of compression.
To check for compression, you’ll want to perform what is called a leak down test. This process involves a special compression tester kit. You remove the spark plug and hook the compression tester kit in its place.
It’s not a very difficult test to run but there are some steps you must do to get it done right. If you want to perform the test, I suggest you visit my Top 7 Reasons An ATV Will Smell Like Burning Oil article and scroll down to the leak down test section. If you did have a blown piston ring, the compression test will tell you, and it will cause oil to leak into the combustion chamber causing a burning oil smell.
Old Gas In Tank?
Having gas just as old as 6 months or so can start to cause corrosion in your fuel system. Make sure if you’re going to let the quad sit for a while that you drain the gas out and start with new gas next time you start it up.
If you think it won’t start because you’ve had old gas sitting in the tank for a while, it’s a good idea to also change the fuel filter. Get some good fresh gas in the tank and use an additive to help the clean the fuel system. I use this Gumout Complete Fuel System Cleaner from Amazon every year before I start riding in the spring.