Truth be told, we are always in the habit of overfilling our gas tanks for reasons best known to us. I’m a culprit of this; always filling my gas tank to the tip top for one reason or the other; either when I’m on a journey or after adding fuel injector cleaner or catalytic converter cleaner into my gas tank.
Sometimes I overfill the gas for no reason until one day I encountered a problem that made me stop it for that car. I started the habit again after I bought another car.
So, as a driver who has been driving for years and has owned several cars, I will be sharing my experience with overfilling my gas tank and what happens when you do so, so you can learn from my experience and make your decision.
Can You Overfill Your Gas Tank?
Yes, of course, it is possible to overfill your gas tank if you continue pumping fuel into the gas tank beyond its maximum capacity.
One thing with most modern cars is that they come with a mechanism that helps to prevent overfilling, known as an automatic shut-off valve or nozzle.
When the fuel level reaches a certain point within the tank, this valve triggers, causing the pump to shut off automatically.
However, despite the presence of this mechanism, it is still possible to overfill the tank if you attempt to force more fuel into it after the automatic shut-off has engaged.
Some people go to the extent of manually overriding the automatic shut-off valve by holding the pump handle in the “on” position even after it has shut off.
What Happens if You Overfill Your Gas Tank?
Don’t get it twisted. While overfilling the gas tank occasionally may not cause immediate harm to the car, if you continue to overfill the gas tank repeatedly, it can lead to issues such as fuel spillage, damage to emission control systems, and other mechanical problems.
Here’s what happens when you overfill your gas tank:
1. The Fuel Will Spill on the Ground
If you overfill your gas tank, it can cause the fuel to spill out of the tank and onto the ground. This is the number one risk of overfilling a gas tank as it poses a safety risk, particularly if the spilled fuel comes into contact with hot surfaces, sparks, or flames, it can ignite, causing fires or explosions, which will endanger both individuals lives and property in the vicinity.
Remember when I said I used to overfill my car’s gas tank until I encountered a problem? Well, it was a 2005 Peugeot 307 SW. I had been driving this car for months and filling the gas tank to the tip-top without any issues. But on that faithful day, while I was pumping the gas, it started to spill without me knowing.
The worst part was that the spillage was not coming from the gas cap side, but rather, under the car. While it was spilling, I was busy pumping the gas until I perceived the smell of gas. That was when I looked under the car and saw the spillage. By that time, it had spilled too much, wasting gas and my money.
Although I later fixed the problem within the fuel tank that caused the spillage to come from beneath the car, that was the last time I overfilled the Peugeot until I sold it and bought another one.
So apart from the gas spilling from the gas cap side, it can also spill from under the car if there’s something wrong with the gas tank seal. I’ve also witnessed this happen to two different people in a gas station. They joined me to learn the hard way.
2. Overload on the Evaporative Emissions System
Modern vehicles are equipped with an evaporative emissions control system, which is designed to capture fuel vapors and prevent them from being released into the atmosphere.
When you overfill the gas tank, you risk overwhelming this system. Excess fuel can flood the system, leading to increased emissions of harmful pollutants.
Furthermore, this overload can trigger the vehicle’s ECU to throw some error codes, causing the check engine light to come on.
3. It May Cause Damage to Vapor Recovery Components
Overfilling the gas tank can also cause damage to components of the vapor recovery system. This system is responsible for capturing fuel vapors generated during refueling and returning them to the fuel tank to prevent their release into the environment.
Therefore, excessive fuel can flood or saturate the system, leading to malfunctions or failures that may make you perform costly repairs.
4. It May Damage the Fuel Pump
While this is not common, overfilling your gas tank with too much gas can cause your fuel pump to spoil. You will just have a sudden fuel pump damage. This is also the reason why some people complain about their car not starting right after buying gas.
Liquid fuel entering the charcoal canister or flooding the fuel pump module is indeed a risk associated with overfilling the gas tank.
This can occur when fuel levels exceed the capacity of the tank or when fuel is forced into components not designed to handle liquid fuel.
If this continues and becomes a habit, it may lead to premature wear or damage to the fuel pump, therefore, compromising its performance and efficiency.
5. It is Not Good for the Environment
Having the habit of constantly overfilling your gas tank is not good for the environment because of the gas spilling on the ground.
Spilled fuel not only poses immediate safety risks but also has long-term environmental consequences. When fuel contaminates soil and water sources, it can harm ecosystems and wildlife.
Furthermore, the release of fuel vapors into the atmosphere contributes to air pollution and negatively impacts air quality.
The day I had a spillage in my Peugeot 307 SW, it was through the smell of gas that I noticed that something was wrong. By that time it had spilled too much.
Now, imagine if something happened and lit the fuel, what do you think would happen? This is why it’s not good for your car to be on while buying gas. The heat from under your car can ignite the spilled gas and cause a fire.
We are not saying you should not fill your tank to the desired gauge, but when filling the tank with gas, ensure you don’t overfill to the extent that it spills on the ground, its disadvantages are disastrous.
Why Do People Overfill Their Gas Tank?
Here are common reasons why people overfill their gas tanks:
- They Misjudge the Capacity of the Fuel Tank: Sometimes, drivers may misjudge the amount of fuel needed to fill their tank, making them continue pumping the gas even after the tank is full. This can occur due to distractions, multitasking, or simply underestimating the tank’s capacity.
- They Attempt to “Top Off”: Some drivers believe that topping off the gas tank, i.e., adding a little extra fuel beyond the automatic shut-off point, will give them more mileage or save them from refueling sooner. However, this practice is generally unnecessary and can lead to overfilling, fuel spillage, and damage to the vehicle’s emissions control system.
- They May Have a Faulty Fuel Gauge or Indicator: In some cases, the fuel gauge or indicator in the vehicle may provide inaccurate readings, leading the driver to believe that the tank has more room for fuel than it actually does. This can result in overfilling as the driver tries to achieve what they perceive as a “full” tank.
- It Has Already Become a Habit or Routine: Overfilling the gas tank can become a habitual behavior for some drivers, especially if they are accustomed to filling up until the pump shuts off without considering the actual capacity of the tank.
- They are Distracted or in a Rush: Distractions, time constraints, or multitasking while refueling can contribute to overfilling. Drivers may not pay close attention to the fueling process or the automatic shut-off mechanism, leading them to overfill the tank.
- They May Want to Optimize the Fuel Price: In regions where fuel prices fluctuate frequently or where there are discounts for bulk purchases, some drivers may try to maximize their purchase by filling the tank to its absolute capacity, even if it means overfilling slightly.
What Do I Do if I Overfill My Gas Tank?
If you accidentally overfill your gas tank, here are steps you can take to mitigate any issues:
Step 1: Stop Pumping Immediately
As soon as you realize that you’ve overfilled the gas tank, the first step is to stop pumping fuel. If you continue to add more fuel to the tank, you will end up worsening the situation and increase the risk of it spilling on the floor.
Step 2: Check for Any Spillage and Neutralise it
After you have stopped adding more gas to the tank, the next thing to do is check for any form of spillage. Look around the fuel filler neck and the ground beneath your vehicle for any signs of fuel leakage.
If there is indeed a spillage, take a moment to assess its extent and use something to neutralize the spilled gas before starting your vehicle.
If your car was on while pumping the gas, please turn it off immediately and pour water into the area where the spilled gas is. The water will neutralize the effectiveness of the gas from fire, making it less hazardous. Wait for a while before starting your car again.
You can also use paper towels, rags, or kitty litter to soak up the spilled fuel. Wipe down the affected areas thoroughly to minimize the risk of ignition and environmental contamination.
Don’t forget to dispose of any used absorbent materials properly. Avoid disposing of fuel-soaked materials in regular trash bins or drains.
Step 3: Start the Vehicle and Drive Off
You can now start your car and continue your journey. However, while driving, you need to keep an eye on your vehicle’s dashboard for any warning lights or unusual behavior, such as rough idling or difficulty starting the engine.
Overfilling the gas tank can sometimes trigger the check engine light or affect the vehicle’s emissions control system.
Nevertheless, if you notice any persistent issues with your vehicle afterward, take your car to the mechanic or an auto shop where the issue will be diagnosed and fixed.
Can Overfilling Gas Tank Cause Car to Stall?
Yes, even though it’s not a common occurrence, overfilling the gas tank can cause the car to stall.
If while overfilling your gas tank, liquid fuel enters into the vapor recovery system and floods it, it can disrupt the proper operation of the system and cause the engine to stall or idle rough.
Also, if liquid fuel enters the charcoal canister due to overfilling, it can become saturated, leading to issues with fuel vapor storage and causing stalling or hesitation during acceleration.
In extreme cases, your car can stall if, during the cause of overfilling your gas tank, fuel entered into the engine’s cylinders, it can cause a condition known as hydro-lock, which occurs when liquid fuel fills the combustion chamber, preventing the pistons from moving smoothly and causing the engine to stall or seize.
Can Overfilling Your Gas Tank Cause the Check Engine Light to Come On?
Yes, overfilling your gas tank can cause the check engine light to come on especially when the overfilled tank allows fuel to enter into the evaporative emissions control system such as the charcoal canister, purge valve, and vent valve, it can lead to saturation or contamination.
This can disrupt the normal operation of the evaporative emissions control system, causing it to malfunction. However, when the system detects a fault or irregularity, it may trigger the vehicle’s ECU to illuminate the check engine light.
Furthermore, overfilling the gas tank can also cause other issues that may indirectly result in the check engine light coming on.
For example, if liquid fuel enters the engine’s cylinders or if the fuel level sensor becomes damaged due to overfilling, it can lead to engine performance issues or inaccurate fuel level readings, causing the check engine light to come on.
Conclusion
Overfilling your gas tank has so many effects ranging from safety threats, vehicle malfunctions, environmental damage, and financial costs associated with repairs. Therefore, while buying gas, avoid overfilling the gas tank to the extent of it spilling on the ground because the disadvantages are disastrous.
