ATV Flooded With Gas: Why it Happens and How to Fix

When your ATV is flooded with gas, causing the engine not to start, rest assured you’re not the only one who has encountered this annoying issue.

This article dives into the common symptoms and causes of this problem and provides practical solutions to get you back on the trails.

What is Gas-Flooding in an ATV?

ATV flooding with gas is when excessive gasoline accumulates in the engine’s combustion chamber or carburetor, impairing the engine’s ability to start and run efficiently. 

This typically happens when the fuel system delivers more fuel than the engine can efficiently burn. The excess fuel can dampen the spark plugs, making it difficult or impossible to ignite the fuel-air mixture essential for engine operation. 

It often manifests as a strong gasoline smell, difficulty starting the engine, or a noticeable fuel leakage. 

If not addressed, it can lead to reduced engine performance, potential damage to engine components, and increased risk of fire hazards. 

Symptoms of ATV Gas Flooding

Excessive Fuel Smell: When your ATV is flooding with gas, you’ll often notice a strong and persistent odor of gasoline, especially around the engine area. This is caused by excess fuel leaking or evaporating from the carburetor or fuel injection system.

Difficulty Starting the Engine: An engine flooded with gas will struggle to start or might not start at all. This happens because the spark plugs are wet with fuel, preventing them from igniting the fuel-air mixture effectively.

Overflow of Gas: In some cases, you might see gasoline overflowing from the carburetor or pooling underneath the ATV. This is a direct indication of too much fuel in the system.

Engine Stalling or Running Roughly: If your ATV starts but then stalls or runs unevenly, this could be a symptom of flooding. Excess fuel can cause the engine to choke and stall or run erratically.

Black Smoke from Exhaust: Excessive fuel in the engine can lead to incomplete combustion, often resulting in black exhaust smoke.

Wet Spark Plugs: When inspecting the spark plugs, if you find them to be wet with fuel, it’s a clear sign that the engine is flooding. Wet spark plugs cannot generate an adequate spark for combustion.

Increased Fuel Consumption: An ATV that keeps flooding with gas will often consume more fuel than usual. This is due to the excess fuel injected into the engine, much of which goes unburnt.

Causes of ATV Flooding with Gas

1. Incorrect Startup Procedure

Using the wrong startup procedure, such as excessively pumping the throttle or improperly using the choke, can lead to excess fuel entering the engine. 

Solution:

• Follow the manufacturer’s recommended startup procedure for your ATV. Read our simple 5-step guide on how to start an ATV.
• Only use the choke for cold starts. The choke enriches the fuel mixture to assist with cold starts. When used on a warm engine, it can flood the engine with too much fuel. 

2. Clogged Air Filter

A clogged air filter restricts the airflow into the engine, leading to an overly rich fuel mixture and potential flooding.

Solution:

• Regularly inspect and clean the air filter. 
• If it’s excessively dirty or damaged, replace it to ensure proper air intake.

3. Faulty Carburetor Float

The carburetor is responsible for mixing air and fuel in the correct ratio. The carburetor float regulates the fuel level within the carburetor. If the float is faulty, it can cause an excessive fuel flow into the engine, leading to flooding.

Solution:

• Check the float for damage or sticking and replace it if necessary.
• Ensure the float height is adjusted correctly according to your ATV’s manual.

4. Stuck Choke

If the choke is stuck in the closed position, it can lead to an over-rich fuel mixture, causing flooding.

Solution:

• Check the choke cable and linkage for smooth operation.
• Clean or replace any parts that are sticking or damaged.

5. Dirty or Clogged Carburetor

A carburetor that is dirty or clogged with debris can disrupt the fuel-air mix, leading to an imbalance and potential flooding.

Solution:

• Clean the carburetor thoroughly, paying attention to jets and passageways.
• Replace any worn or damaged parts.

6. Fuel Injection Issues

For ATVs with fuel injection systems, fuel injection issues like leaking fuel injectors and faulty fuel pressure regulators can lead to flooding. 

A leaking injector drips excess fuel into the cylinder, while a malfunctioning fuel pressure regulator can force too much fuel into the engine due to incorrect pressure maintenance.

Solution:

• Inspect the injectors for leaks or damage. Replace faulty injectors and ensure proper installation.
• Test the fuel pressure with a gauge. Replace the regulator if it’s not maintaining the correct pressure.

7. Bad or Contaminated Gas

Bad, contaminated, or the wrong type of gasoline can lead to poor engine performance and flooding.

Solution:

• Use fresh, high-quality gasoline suitable for your ATV. 
• If you suspect the gas is bad or contaminated with water, drain the tank and refill it with fresh fuel.

8. Excessive Cranking

Excessive engine cranking without starting can cause the carburetor or injectors to flood the engine with fuel.

Solution:

• Allow the engine to rest for a few minutes before attempting to start again.
• Check other systems (spark, air intake) to ensure they are not causing your ATV to turn over without starting.

9. Drained Battery

A weak battery may not provide enough power to turn the engine fast enough to generate a strong spark and sufficient compression to start the engine, leading to the accumulation of unburnt fuel.

Solution:

• Regularly check the battery’s charge and health. 
• If it’s weak or old, consider recharging or replacing it to ensure sufficient power for starting the engine.

10. Ignition Issues

Problems with the ignition system can prevent the fuel-air mix from igniting. 

Possible culprits include a bad plug cap, faulty coil wire, defective coil or pickup, faulty stator, malfunctioning CDI or ECU module, or a fouled or faulty spark plug. 

Solution:

• Inspect and replace the spark plugs if they are fouled or faulty.
• Check the plug cap and coil wire for any signs of wear or damage and replace them if necessary.
• Test the ignition coil and replace it if it’s defective.
• Test the Stator and CDI module for proper functionality, replacing them if needed.
• Examine the pickup, ensuring it is in good condition and replacing it if there are faults.

11. Poorly Adjusted Air-Fuel Mixture

An incorrectly adjusted air-fuel mixture can be either too rich or too lean. A too-rich mixture can cause flooding.

Solution:

• Adjust the air-fuel mixture according to the manufacturer’s specifications.
• Consider having a professional tune-up if you are unsure about making adjustments.

12. Mechanical Issues

Various mechanical problems, such as a stuck valve, damaged piston rings, or timing issues, can disrupt the normal operation of the engine and cause flooding.

Solution:

• These issues typically require a more in-depth mechanical inspection and repair. It’s advisable to consult with a professional mechanic to diagnose and fix complex mechanical problems.

How to Un-Flood a Flooded ATV

If your ATV is flooded with gas, there are several methods you can try to resolve the issue. 

1. Open Throttle Cranking

The first method involves using the throttle while cranking to let more air into the combustion chamber, helping to clear out excess fuel.

1. Turn off the choke.
2. Hold the throttle in the fully open position.
3. While holding the throttle open, crank the engine for a few seconds.

2. Waiting for Gas Evaporation

Another method is to wait for the excess gas to evaporate. This more passive approach can be effective if the flooding is not severe. 

With the engine off, leave the ATV in a well-ventilated area for a while, allowing the excess gasoline to evaporate naturally. 

Depending on the extent of flooding and environmental conditions, this may take 10-15 minutes up to several hours.

3. Removing the Spark Plug to Clear Cylinder

The third method involves removing the spark plug and cranking the engine to physically expel excess gas from the combustion chamber.

1. Disconnect the ignition coil power feed to prevent damage to the coil during the process.
2. Remove the spark plug from the engine.
3. Cover the plug hole with a rag to soak up the fuel as it is expelled.
4. Crank the engine to expel excess gas.
5.  Reattach the spark plug and power feed before attempting to start the engine.

Tips to Prevent ATV Flooding With Gas

• Learn the Proper Startup Procedure: Read and practice the manufacturer’s recommended startup procedure.
• Regular Maintenance: Adhere to the maintenance schedule in your ATV’s manual, focusing on engine and fuel system care.
• Fuel Quality: Always use fresh, high-quality fuel and drain old fuel if the ATV hasn’t been used for a while.
• Prepare the ATV for Storage: Adding a fuel stabilizer to the gas is one of the steps in our ATV long-term storage preparation checklist.

Check this guide if you struggle to get your ATV to start after sitting.