If your snowmobile won’t start or accelerate, it’s usually because of fouled spark plugs, fuel or carb issues, or perhaps a flooded engine. If your snowmobile has a battery, its failure, or a bad starter could also be why your sled won’t start.
If your snowmobile won’t start or accelerate properly, this post is for you.
In addition to the typical issues mentioned above, we’ve compiled many other potential problems and their fixes under one roof.
Let’s see how to troubleshoot a snowmobile step-by-step!
Why is My Snowmobile Not Starting?
There could be several reasons why your snowmobile won’t start, but some issues are more common than others. The following problems are the most common, so it’s recommended that you check for them one-by-one:
- Dead battery
- Carb/fuel/fuel line problems
- Bad starter/starter relay/coils (no spark)
- Dirty or defective spark plugs
- Wrong spark plug gap settings
- Incorrect ignition timing
- Stop switch malfunction
- Damaged computer
- Flooded engine
- Low compression in the cylinders
- Broken piston rings, or some other major engine damage
(Disclaimer: Before you start to service your sled, always read the owner’s manual carefully. If you don’t have mechanical skills, best practice is to take the sled to your dealer or a reputable service shop.)
One of the most common reasons why a snowmobile won’t start is a dead battery. However, not every sled has a battery, but if it features an electric start then it has a battery as well.
It’s important to know that snowmobile batteries self-discharge over time. That’s why you should keep it on a battery tender during the summer or when you aren’t using your sled for a long period of time.
If you notice that your snowmobile’s battery is weak, just give it a good charge and try starting the engine again. Best practice is to let it charge overnight.
Starter and Starter Relay
If your snowmobile features an electric start, this means it has a starter and a starter relay. These parts can also sometimes go wrong.
If you hear one or more clicks but your snowmobile still won’t start, you should check these parts. As a rule of thumb, you can determine the cause of the problem by the number of clicks.
If you hear multiple clicks, it’s a sign of a week battery. If you’ve charged the battery but your sled still won’t start, check the battery with a voltmeter. It might be so dead that it needs to be replaced.
If the starter relay makes only one click, this usually means that there is an issue with the relay. If it’s broken, you will need to replace it. Before replacing it, it would be wise to remove and test it. Here’s a good step-by-step video on how to test a snowmobile starter relay:
It’s also good to know that snowmobile starter relays are sometimes called starter solenoids as well.
Sparks are also essential for a snowmobile engine to start. The sparks are generated by the spark plugs, which are fortunately easy to test and replace.
Bad or fouled spark plugs is one of the leading reasons why snowmobile engines won’t start, especially on carbureted 2-stroke sleds.
To replace the spark plugs, you just need a socket wrench with an extension. Remove the plugs and examine them. If they have a light brown color while being completely dry, it’s a clue that the fueling is correct.
If you notice that the spark plug is wet, there could be a carb or ignition issue on that cylinder.
Keep in mind that if you have a carbureted snowmobile, you will have to periodically clean or even adjust the carbs.
This is often necessary after the sled has been sitting for a while. This is because the gas is likely to evaporate from the carb while the sled is sitting, leaving the oil behind. When you try to start the engine, this oil makes the mixture too rich, which may end in fouled spark plugs. Finally, this is the root cause for the snowmobile not starting.
How do You Check a Snowmobile for Spark?
To check a snowmobile’s spark, first remove the spark plugs. Reconnect the cap and touch the metal part of the plug to the metal surface of the engine. At the same time, try to crank the engine. You should see sparks at the end of the spark plug. To make sure every plug works properly, you have to check them one-by-one.
If you can’t see any spark, you should then make sure that the plugs have correct gaps. If not, adjust them based on the manufacturer’s recommendation. As the next step, check the connection of the cap and the other cable connections as well. Disconnect the ignition switch and shut-off switch, and check for sparks again. If they appear, it probably means that there is an issue with one of these switches or with their wiring. If there is still no improvement in sparks, you may want to test the stator with a voltmeter.
Spark plugs issues are common reasons why snowmobiles won’t accelerate or even start properly.
Because of this, especially if you have a 2-stroke sled, it’s wise to have an extra set of plugs on you with the necessary socket set. You never know when you might have to check or even replace the plugs!
Why does my snowmobile have no spark?
If your snowmobile has no spark at all, the cause could be many issues. Sometimes the plugs are just wrong and need to be replaced. If this won’t help, check the wires and the spark plug caps, as they are also prone to breaking. If they look good, it may be a problem with the stator or other parts of the electric system.
Fuel and Fuel Line Issues
If your sled won’t start or accelerate, it may be caused by wrong the fuel or the fuel line.
As the first step, make sure that there is enough gas in the tank, and it is reaching the entire fuel line. Always use the right type of fuel according to the manufacturer’s specifications.
The gas also should be fresh. If you haven’t used your sled for a while and didn’t add stabilizer to the gas, then there is a good chance that the gas is stale. If this is the case, you should remove the old gas, clean the carbs, and refill the tank with fresh gas.
A flooded engine is one of the most common reasons for a snowmobile not starting. A flooded engine means that gas has leaked into the cylinders or even the crankcase while the sled was stored or being transported.
Also, keep in mind that if you crank the engine too long while trying to start it, this too can lead to a flooded engine. To avoid this, always take a short break before trying to start your engine again.
How do I know if my snowmobile is flooded?
If you can’t start your snowmobile and you smell gas, or see that gas is coming out of the exhaust, it’s a clue that your snowmobile is flooded. Remove the plugs and inspect them. If they are wet, that means your engine is flooded and the gas needs to be removed from the cylinders.
How do you fix a flooded snowmobile engine?
To fix a flooded snowmobile engine remove the spark plugs and crank the engine a couple of times. If it’s flooded, you will probably see a mist coming out from the plug holes. Dry and replace the spark plugs and try starting the engine. If gas has leaked into the crankcase, it can cause a hydrostatic lock. To eliminate this, remove the plugs, which can be found on the bottom of the crankcase. (Make sure you remove the right plugs!)
If your snowmobile floods too quickly, this probably means that you need to clean or even rebuild the carburetor. For further steps please refer to the owner’s manual or take your sled to the dealer.
Major Engine Problems
You can easily solve the above-mentioned problems by yourself.
But in the worst of cases, the reason your sled won’t start could be due to a serious engine problem.
First, check the compression in the cylinders with a compression tester. If it’s low that’s a very bad sign.
A common issue is when the gaskets are damaged and need to be replaced.
The worst scenario is probably when the engine is worn out or seized and need to be rebuilt. Seizure is serious engine damage mainly caused by poor lubrication or insufficient cooling.
If this happens, best practice would be to contact your dealer or a service shop.
If a 4-stroke snowmobile won’t start, the problem could also be an incorrect oil level in the engine. Check the oil level with the dipstick and adjust if necessary.
What to do if Your Snowmobile Won’t Idle
Another common problem is when a snowmobile starts but it won’t idle. In many cases, it’s caused by improper clutch settings or carb issues. Moreover, don’t forget that the altitude also affects engine performance. This means you will have to adjust your sled’s settings based on the altitude where you’re riding. Let’s take a closer look at the ideal RPMs that a snowmobile should idle at.
What RPM Should a Snowmobile Idle at?
Snowmobiles should idle around 1000-2000 RPMs depending on the make and model. As a rule of thumb, the average snowmobile idles around 1500 RPMs. Keep in mind that the idle RPM depends on many factors like the altitude, ambient temperature, and the temperature of the engine. You should expect higher idle RPMs on crisp days and lower RPMs on warm days.
Why is My Snowmobile Idling High?
If your snowmobile is idling high, this probably means that it’s running lean. Simply put, it means that the air/fuel mixture is wrong, as the air contains too little fuel when entering the cylinders. Beyond this, a high idle can also be caused by a throttle cable problem. Sometimes this just needs to be adjusted on the carb to solve the issue. Many carburetors also feature an “idle screw” on top, so it can simply be adjusted for a lower RPM.
If none of this helps, you probably have to drill deeper and adjust the air/fuel mixture.
How do I Know if My Snowmobile is Running Lean?
Best practice for determining whether your sled is running lean or not is to check the color of the spark plugs. Remove them and check their colors. If they are a nice tan in color this means the mixture is right, but if they are white, your snowmobile is running lean. On the other hand, if the plugs are black this is a clue that your sled is running too rich.
How do You Adjust the Carburetor on a Snowmobile?
To adjust a snowmobile carburetor, make sure that you warm up the engine first. Then, you can adjust the mixture with the fuel and air screws on the carb. (Beware that older sleds don’t feature air screws.) Turn the air screws in and the fuel screws out, making only small adjustments at a time, and check the results. Be careful as finding the sweet spot could be tricky and require some practice.
Why is My Snowmobile Bogging?
The most common reasons for a snowmobile bogging are the following problems:
- fuel line issues
- wrong fuel
- clogged fuel filter
- carburetor issues (cleaning or adjustment needed)
- spark plug or other electric problems
- wrong seals
- drive belt issues
If your snowmobile bogs down, always check the manual for further steps or contact your dealer for further guidance.
Why is My Snowmobile Not Accelerating Properly?
If your snowmobile won’t accelerate properly, it may be caused by one of these problems:
- Drive belt issues
- Clutch issues
- Jammed track
- Chain issues
- Wrong fuel/fuel line/fuel filter
- Fouled or defective spark plugs
Can you start a snowmobile without a battery?
You can start a snowmobile without a battery if it doesn’t feature an electric start. What’s more, these models usually don’t have a battery at all. Generally, 4-stroke and older fuel injected snowmobiles only need a battery to run.
Can you jump start a snowmobile?
Keeping safety in mind it’s not recommended to jump start a snowmobile. This is because there is a risk that you burn the computer in your sled, or even in your truck/car! This can lead to a costly repair bill. Unfortunately, today’s vehicles have very sensitive electronic parts, therefore jump starts are not recommended with these batteries.
How do I know if my snowmobile coil is bad?
If your snowmobile coil is bad, the engine is hard to start or won’t start at all. Another symptom is the sled running bad at low RPMs (bad low-speed coil) or runs bad at high RPMs (bad high-speed coil). If your snowmobile is backfiring, this could also be a sign that the coil is going bad.
How do I know if my snowmobile fuel pump is bad?
A bad fuel pump is a common reason why a snowmobile won’t start or accelerate. If your snowmobile fuel pump is bad, you will probably notice that your sled regularly loses power, or even won’t start at all. Keep in mind that a clogged fuel filter can cause very similar symptoms as a broken fuel pump!
Can you use starting fluid on a snowmobile?
As a rule of thumb, don’t use starting fluid on a snowmobile unless it contains lubricant. Starting fluids generally don’t contain any lubricant, therefore they can wash the oil off in the cylinders, which may end in engine damage. If you want to use starting fluid at all costs, make sure that it contains lubricant, so you avoid these issues.
Conclusion – What Can You do if Your Snowmobile Won’t Start?
Simply put, snowmobile engines mainly need the following to run: gas, oil, air, and a spark.
If your snowmobile won’t start, first always make sure that the off switch isn’t pushed in, the battery isn’t too weak, and there is fresh gas in the tank. If your sled still doesn’t start, you should check the spark plugs, the carburetor, and the fuel line. In most cases, one of these parts is the source of the problem.
Beyond these typical issues, there could be many other reasons why your snowmobile won’t start, such as:
- Starter/starter relay/computer issues
- Wire or connection problems
- Flooded engine
- Bad gaskets
- Low compression in cylinders
- Damaged engine
Best practice is to check for these issues one-by-one.
As a final word, before you try to fix your snowmobile by yourself, always read the manual carefully and follow the manufacturer’s recommendations.
If you don’t have any mechanical skills or the required tools, it’s recommended that you take your sled to a repair shop.
This is our short snowmobile troubleshooting guide. We hope you find it useful!