The Polaris Predator 90 is a popular youth ATV, but even these reliable machines can present challenges. A common issue is when the ATV refuses to run with the airbox removed. This isn't simply a matter of needing more air; it often points to underlying problems that need addressing. This guide will explore the potential causes and provide troubleshooting steps to get your Predator 90 running smoothly again.
Why Won't My Polaris Predator 90 Run Without the Airbox?
Removing the airbox on most ATVs, including the Predator 90, shouldn't cause a complete failure to run. While increased airflow might seem beneficial, the absence of the airbox drastically alters the air/fuel mixture, leading to various problems. Here's why it won't run:
-
Incorrect Air/Fuel Mixture: The airbox is crucial for regulating the amount of air entering the carburetor. Without it, the engine receives far too much air, creating a lean mixture. This lean condition can prevent the engine from igniting properly or even damage it over time.
-
Vacuum Leaks: The airbox helps maintain the correct vacuum within the engine's intake system. Removing it creates significant vacuum leaks, disrupting the delicate balance of air and fuel delivery.
-
Sensor Issues (if equipped): Some later models might have air intake sensors that rely on the airbox's presence for accurate readings. Removing it can trigger a malfunction, preventing the engine from starting or running.
-
Dirt and Debris: Without the airbox's filtering system, the engine is exposed to dirt and debris, which can quickly clog the carburetor or damage internal components.
Troubleshooting Steps: Polaris Predator 90 Airbox Issues
Let's systematically address the problem:
1. Check for Obvious Obstructions:
-
Clean the Air Filter: Even if you're troubleshooting without the airbox, a clogged air filter can still impede airflow, even with the airbox removed. Thoroughly clean or replace the filter.
-
Inspect the Carburetor: Look for any debris blocking the carburetor's jets or passages. Use compressed air carefully to remove any obstructions.
-
Examine the Intake Manifold: Check for cracks or leaks in the intake manifold connecting the airbox to the carburetor. A faulty seal here can disrupt the air/fuel mixture even with the airbox in place.
2. Carb Adjustment and Cleaning:
-
Carb Cleaning: The carburetor is the heart of fuel delivery. A thorough cleaning is often necessary. This might require specialized tools and knowledge, so consider seeking professional help if you're uncomfortable performing this step.
-
Pilot Screw Adjustment: The pilot screw controls the idle fuel mixture. Adjusting it (after cleaning) may help compensate for any lean conditions resulting from the removed airbox (though it won't solve the underlying issue). Refer to your owner's manual for the correct adjustment procedure.
3. Verify Fuel Delivery:
-
Check Fuel Line: Ensure the fuel line is free from kinks, cracks, or blockages. A restricted fuel supply will prevent the engine from starting or running properly.
-
Fuel Filter: Inspect and clean or replace the fuel filter. A clogged filter will impede fuel flow.
4. Spark Plug Check:
- Inspect the Spark Plug: Check the spark plug for fouling or damage. A faulty spark plug can prevent proper combustion, even with sufficient air and fuel. Replace if necessary.
5. Ignition System Check:
- While less likely related to the airbox removal itself, issues in the ignition system (coil, wires) can prevent the engine from firing.
Addressing the Root Cause: Why the Airbox is Essential
Remember, the airbox is not just a random part; it's critical for protecting the engine and maintaining the proper air/fuel ratio. Running the ATV without it, even if it sometimes seems to work temporarily, risks engine damage due to a lean mixture. Always reinstall the airbox and address any underlying issues discovered during troubleshooting.
When to Seek Professional Help
If you've followed these steps and your Polaris Predator 90 still won't run, it's best to seek the assistance of a qualified ATV mechanic. More complex issues, like carburetor problems or internal engine damage, may require specialized tools and expertise. Trying to fix these problems without proper knowledge could cause further damage.
