There’s nothing more frustrating than seeing the excitement on your kid’s face vanish when their Can-Am DS 90 starts up, only to sputter and die the second you let off the throttle. That familiar “vroom… put-put… silence” is a sound that can end a day of fun before it even begins.
But don’t worry, we’re here to turn that frustration into a fist-pump of victory. We’ve been there, covered in grease, scratching our heads. This guide will walk you through the most common culprits when a can am ds 90 won’t idle, empowering you to get that little machine purring again.
We’ll cover everything from the simplest checks you might have overlooked to cleaning the carburetor and inspecting the spark system. Let’s get those tools out and get that DS 90 back on the trail where it belongs.
First Things First: The Simple Checks Before You Panic
Before you start tearing things apart, let’s cover the basics. More often than not, an idle issue is caused by something simple. Running through these checks first can save you a ton of time and headache.
Is the Fuel Fresh and Flowing?
Gasoline, especially the ethanol-blended stuff we get today, goes bad surprisingly fast. Stale fuel loses its combustible properties and can clog up tiny fuel passages.
First, check the fuel in the tank. Does it smell more like varnish than gasoline? If it’s been sitting for more than a month or two, drain it and replace it with fresh, non-ethanol fuel if you can find it. While you’re at it, make sure the fuel petcock is turned to the “ON” or “RES” position, not “OFF”. It sounds obvious, but it happens to the best of us.
What About the Choke?
The choke (or enrichment circuit) makes the fuel mixture richer for cold starts. If the choke is stuck partially on, the engine will run too rich once it warms up, causing it to foul the plug and die at idle.
Locate the choke lever on the handlebars or the carburetor itself. Make sure it moves freely and is fully in the “OFF” or “RUN” position after the engine has warmed up for a minute or two.
Is the Air Filter Clogged?
An engine needs to breathe. A dirty, clogged air filter restricts airflow, making the fuel-to-air mixture too rich. This is one of the most common problems with can am ds 90 won’t idle situations, especially after a dusty ride.
Simply remove the air filter cover, take out the foam filter, and inspect it. If it’s caked with dirt and grime, clean it thoroughly with a proper filter cleaner and re-oil it with filter oil. A clean filter is a happy filter.
The Heart of the Problem: Diving into the Carburetor
If the simple checks didn’t solve it, the carburetor is our next prime suspect. The idle circuit inside the carb has incredibly small passages that get clogged easily by old fuel residue. This is the single most common reason a small engine won’t idle.
Understanding the Pilot Jet (Idle Circuit)
Think of the carburetor as the engine’s chef. It mixes air and fuel into a fine mist. The pilot jet (sometimes called a slow jet) is a tiny brass jet with a pinhole-sized opening. Its only job is to supply fuel when the throttle is closed—in other words, at idle.
When fuel sits, it evaporates and leaves behind a gummy varnish. This varnish is the perfect size to completely block that tiny pilot jet opening, starving the engine of fuel at idle.
A Step-by-Step Guide to Cleaning the Pilot Jet
This might sound intimidating, but it’s a manageable job with basic tools. Here’s a simplified can am ds 90 won’t idle guide for cleaning that critical jet.
Safety First: Work in a well-ventilated area, wear safety glasses and nitrile gloves, and have a fire extinguisher handy. Disconnect the battery’s negative terminal.
- Access the Carburetor: You’ll likely need to remove the seat and side plastics to get good access. Turn the fuel petcock to “OFF”.
- Drain the Fuel: Place a small container under the carburetor and locate the drain screw on the bottom of the float bowl. Loosen it to drain any remaining fuel.
- Remove the Float Bowl: There are typically four screws holding the float bowl (the bottom part of the carb) on. Carefully remove them and gently tap the bowl to break the gasket seal. Be prepared for a little more fuel to spill out.
- Locate and Remove the Pilot Jet: Look inside. You’ll see a couple of brass jets. The pilot jet is the smaller one, usually recessed down in a “tunnel.” You’ll need a small, flat-head screwdriver that fits perfectly to remove it without stripping the soft brass.
- Clean the Jet: This is the most important step. Hold the jet up to a light source. You should be able to see a perfect, tiny circle of light through it. If you can’t, it’s clogged. Use a can of carburetor cleaner with a straw to spray through it. If it’s stubborn, you can *gently* poke the opening with a single strand from a wire brush or a specialized jet cleaning tool. Do not force anything through or you’ll enlarge the hole and ruin the jet.
- Reassemble: Once you can see clearly through the jet, screw it back in (just snug, not overtightened). Reinstall the float bowl and reconnect everything.
Adjusting the Idle Speed and Air/Fuel Mixture
While the carb is accessible, check your adjustments. There are two main screws:
- Idle Speed Screw: This is a larger screw, often with a spring on it, that physically stops the throttle slide. Turning it clockwise increases the idle speed.
- Air/Fuel Mixture Screw: This is a smaller, often recessed screw that fine-tunes the mixture at idle. A good starting point is to gently turn it all the way in until it lightly seats, then back it out 1.5 to 2 full turns.
Why Your Can Am DS 90 Won’t Idle: Spark and Electrical Gremlins
If a carb clean doesn’t do the trick, it’s time to investigate the “fire” side of the combustion triangle: spark. A weak or inconsistent spark can be enough to run at higher RPMs but not strong enough to maintain a steady idle.
Inspecting the Spark Plug
Pull the spark plug out with a spark plug socket. What does it look like? The color and condition of the plug tell a story.
- Black and Sooty: Running too rich (check your choke and air filter again).
- White and Blistered: Running too lean or hot (check for air leaks).
- Oily or Wet: Potential internal engine issues.
- Light Tan/Brown: Perfect! This is what you want to see.
Regardless of color, check the gap with a feeler gauge (consult your owner’s manual for the correct spec) and make sure the electrode isn’t worn down. Spark plugs are cheap—when in doubt, just replace it with a new NGK plug.
Testing for a Weak Spark
To check for spark, you can use an inline spark tester or do it the old-school way. Reconnect the plug to the spark plug cap, and hold the threaded part of the plug firmly against a metal part of the engine block. Have someone crank the engine (make sure the key is on!).
You should see a bright, thick, blueish-white spark jump the gap. If the spark is a weak, thin, orange or yellow color, or if there’s no spark at all, you may have an issue with the spark plug wire, ignition coil, or CDI box.
Air Leaks and Compression: The Less Obvious Villains
If you’ve confirmed you have good fuel delivery and a strong spark, but the idle problem persists, we need to look at the last two pieces of the puzzle: unmetered air and engine compression.
The Telltale Signs of a Vacuum Leak
A vacuum leak, or air leak, happens when air gets into the engine *after* the carburetor. This extra, unmetered air leans out the fuel mixture, causing a high, erratic, or non-existent idle.
The most common culprit is a cracked or poorly sealed intake boot—the rubber piece that connects the carburetor to the engine. Inspect it carefully for any cracks, especially in the folds. With the engine running (if you can keep it alive with a little throttle), you can *carefully* spray a small amount of carb cleaner around the intake boot. If the engine RPM changes, you’ve found your leak.
Why Low Compression Can Kill Your Idle
Compression is the engine’s ability to squeeze the air/fuel mixture before the spark plug ignites it. If the piston rings are worn or the valves aren’t sealing properly, the engine will have low compression. An engine with low compression will be very hard to start and will struggle to maintain an idle.
Testing compression requires a compression tester. This is a bit more advanced, and if you suspect this is the issue, it might be time to consult a professional mechanic.
Best Practices for a Healthy Idle: Your DS 90 Care Guide
Fixing the problem is great, but preventing it is even better. Adopting these can am ds 90 won’t idle best practices will keep that little quad running smoothly for years.
The Importance of Routine Maintenance
This is your ultimate can am ds 90 won’t idle care guide. Regularly clean the air filter, change the oil, and inspect the spark plug. A few minutes of prevention are worth hours of troubleshooting.
Fuel Stabilizer: Your Best Friend
If the ATV is going to sit for more than a few weeks, add a quality fuel stabilizer to the tank and run the engine for a few minutes to circulate it through the carburetor. This prevents the fuel from turning to varnish and clogging that tiny pilot jet.
Eco-Friendly Riding Starts with a Well-Tuned Engine
Thinking about a sustainable can am ds 90 won’t idle solution might seem odd, but it’s relevant. A properly idling and well-tuned engine burns fuel more completely and efficiently. This not only improves performance and fuel economy but also reduces harmful emissions, making your time on the trail a little more eco-friendly.
Frequently Asked Questions About Can Am DS 90 Idle Problems
How do I adjust the idle speed on a DS 90?
On the side of the carburetor, there is a larger screw with a spring on it. With the engine warmed up and running, turn this screw clockwise to increase the idle speed and counter-clockwise to decrease it. Adjust it until the engine idles smoothly without stalling or trying to engage the clutch.
Can old gas really cause my DS 90 not to idle?
Absolutely. It’s one of the most common causes. Old fuel turns to varnish and clogs the tiny pilot jet responsible for idling. If the ATV has been sitting for more than two months, draining the old fuel and cleaning the carb is your best first step.
What’s the most common reason a Can-Am DS 90 won’t idle?
By far, the most common reason is a clogged pilot jet in the carburetor. The opening is so small that the slightest bit of debris or fuel varnish will block it, starving the engine of fuel at idle.
When should I take my DS 90 to a professional mechanic?
If you’ve thoroughly cleaned the carburetor, confirmed you have a strong blue spark, and checked for vacuum leaks, but the problem persists, it’s time to call a pro. Issues like low compression or complex electrical failures often require specialized tools and experience to diagnose correctly.
Troubleshooting a machine that won’t idle can be a process of elimination, but it’s a deeply satisfying feeling when you finally pinpoint the problem and fix it yourself. You’ve not only saved money but you’ve also learned more about how your machine works. Now you have a complete roadmap to tackle the issue head-on.
Get back out there, make some memories, and ride safe!
– The FatBoysOffroad Crew
- 2018 Honda Accord Tire Size – The Ultimate Guide To Perfect Fit, - December 18, 2025
- 2012 Honda Accord Fuse Box Diagram – Your Ultimate Guide To DIY - December 18, 2025
- 2013 Honda Accord Fuse Box Diagram – Your Essential Guide To - December 18, 2025