Snowmobile Won’t Idle or Stay Running: Fix It Guide


A snowmobile that won’t idle or stay running is usually a sign of fault within the air, fuel, or electrical system. Fortunately, the common faults that hinder the engine from staying idle have quick solutions. In this article, we will guide you on how to fix these faults.

Steps to Check When Snowmobile Won’t Stay Running

We have arranged all the steps that you should take below. Kindly note that you only need to take one step at a time.

Adjust the Idle Screw

Your snowmobile won’t idle if the idle screw on the carburetor is not set correctly. The idle screw controls how fuel mixes with air at idle speed. Fortunately, you can adjust the idle screw within minutes.

  • To adjust, you might need to remove the air filter and box so that you can see the carburetor.
  • You will find the idle screw on the carburetor.
  • The screw is always near the choke.
  • Please be careful not to adjust the air-fuel mixture screw while intending to adjust the idle screw.
  • You can differentiate the idle screw from the air-fuel screw by its size.

The idle screw is larger than the air-fuel mixture screw. Once you have identified the right screw, you should adjust it and start the engine to see if it stays running.

Here’s a helpful video showing how to adjust the idle screw so you can see this step in action:

You may need to adjust it a couple of times before the engine will work smoothly. So don’t give up if the first adjustment doesn’t work. However, if you didn’t notice any difference after making several adjustments, then you should carry out the step below.

Adjust the Air-Fuel Mixture Screw

The air-fuel screw controls the amount of fuel and air that enters into the carburetor. If the screw is not adjusted correctly, the engine may not be able to stay running.

You can easily adjust this screw in the same way as the adjustment of the idle screw.

  • Locate the air-fuel screw on the carburetor.
  • It is always on the same side of the carburetor as the idle screw, but it’s smaller in size.
  • After locating the screw, use a screwdriver to tighten it or loosen it.
  • Start the engine after each adjustment and observe if the snowmobile stays running.
  • You may need to adjust the screw a couple of times before the engine works well.
  • Proceed to the step below if you don’t notice any improvement after multiple trials.

Here’s a quick video on setting the air screw on a snowmobile carburetor:

Clean the Air Filter

When the air filter becomes dirty, enough air won’t pass through it and reach the carburetor for proper ignition, so the engine won’t stay running. Cleaning it will help you solve this problem. We will show you two different ways to clean the air filter.

The first method requires a vacuum cleaner.

  • You should start by removing the air filter from the snowmobile’s engine.
  • After that, you should use the standard household vacuum cleaner to remove dirt from the air filter.
  • Ensure you remove dirt from both sides of the air filter.
  • It’s best to start on the side the air would normally enter the filter during operation.

The first method is swift, but if the filter is extremely dirty, a vacuum cleaner may not remove everything. If the air filter still looks very dirty after you have cleaned it with a vacuum cleaner, it means you have to use the method below.

The second method requires water and detergent. Please note that this method will take a longer time, but it’s very effective.

Not all air filters will be able to get cleaned this way, if you have a paper filter or stock filter, your best bet is to just buy a new one.

  • Start the by adding a little quantity of detergent into a clean bucket of water.
  • Dip the air filter into the bucket, and gently scrub off the dirt with your palm.
  • Swirl the filter after scrubbing it for a few seconds and then scrub it once more.
  • Please do not squeeze the filter with both hands.
  • Take the filter out of the water after cleaning it for about two minutes.
  • Rinse the air filter under running water.
  • After rinsing it properly, you should shake off the water it has absorbed.
  • Place it on a clean surface and wait for it to dry.
  • Please note that the filter may take up to a whole day before it dries completely.

Put the filter back in its place after it dries completely. Start the snowmobile and observe if it stays running. If it doesn’t stay running, proceed to the step below.

Here’s a cool video with some tips on cleaning air filters, and the importance of getting a lifetime air filter.

Clean the Carburetor

If the carburetor becomes dirty, the engine won’t stay running. Prolonged use of unclean fuel is the primary cause of a dirty carburetor. You can clean the carburetor in two different ways; you will see those two ways below.

Make sure the choke and the throttle plate on the carburetor are not broken before you start cleaning it. If the carburetor has a broken part, then you should replace it because cleaning won’t solve the problem.

Let’s start with the first cleaning method.

  • Remove the hood that covers the engine.
  • Carefully detach the air filter so that the carburetor becomes exposed.
  • Remove the exterior cover of the carburetor to expose the carburetor’s inlet.
  • Get a carb cleaner and spray it directly into the inlet.
  • Start the engine immediately to make the cleaner work more effectively.

The engine should fire when you start it, so the firing will aid the cleaning. Please do not spray excess carb cleaner into the carburetor. Three seconds of spraying is enough to clean the carburetor.

While the engine is off, you should cover the carburetor with its exterior cover and restore the air filter to its place. Start the engine and observe if it stays running.

I like to use this B-12 Chemtool Carb Cleaner (link to Amazon) because it works fast, and it’s not too expensive.

Let’s talk about the second method of cleaning.

This method requires more effort than the first one, but it’s the best method for an extremely dirty carburetor. Here are the steps you should take.

  • Detach the air filter just like we explained in the first method.
  • After that, you should remove the hose that supplies fuel to the carburetor.
  • Loosen all the screws that hold the carburetor to the engine.
  • Also, you should detach the throttle cable from the carburetor or from the engine to make the carburetor remove freely.

After you have removed the carburetor, you need to remove its bottom part. The bottom part will remove when you unscrew all the screws on it.  When you remove the bottom part, you will see a pin at the center of the carburetor.

  • Use needle-nose pliers to remove this pin.
  • You will see the float below the place where you removed the pin.
  • Remove the float also and unscrew the jets.
  • You will easily identify jets since they are screws with a hole at their centers.
  • Also, remove the air screw and idle screw from the outer part of the carburetor.

Now that the carburetor parts are open, it’s time to clean them up. Spray carb and part cleaner to each of the removed parts while you scrub them gently with a wire brush. Ensure you clean all the holes also. Dry all the parts after you clean them.

Reinstall all the parts that you removed and fix the carburetor to the engine. Start the engine and observe if it stays running. You can adjust the idle screw a little until the engine runs smoothly. If the cleaning doesn’t seem to have helped, then you should move to the step below.

Here’s a full walk-through video of cleaning a snowmobile carburetor that may help you out:

Replace the Stator

A stator produces the electrical current that ignites the mixture of air and fuel in the carburetor. If the stator doesn’t generate the right amount of current, the engine won’t stay running. To verify whether the stator in your engine is faulty, you should remove the hood that covers the engine.

Check the part that houses the motor. Many snowmobile manufacturers place the stator inside the motor. The stator comprises several thin steel plates that join together to form a core. The core usually has a powder coating or plastic protection. After you have identified the stator, you should examine it for damage.

If the stator is damaged, you will notice signs such as a missing wedge, missing block, burns, coat cracking, discoloration in the winding, worn-out plates, swollen plates, bents, and cuts.

If you notice any of these signs, then you should replace the stator. Ensure you buy only the right kind of stator for your snowmobile.

Here’s a quick video showing you how to check if the stator is working properly or not.

Before you start the engine, make sure you clean the stator’s connector. If the connector is rusty, it can lead to excessive generation of heat that may burn the new stator.

The stator’s connector is easy to clean since you only need to remove rust from it and apply dielectric grease to its contact points. You should start the engine after cleaning the connector and observe if your snowmobile now stays running.

Rob

That's me sinking another ATV. I love to ride no matter what it is, snowmobiles, four wheelers, dirt bikes, and anything else off-roading. I've experienced my fair share of machines, and like to share that experience here.

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