What Happens If You Overfill Your Gas Tank [What To Do]

When you want to fill your gas tank, most of the time is just adding a small amount of fuel and you are back on the road. However, what about when you want to get a full tank? That is when you may easily overfill even though it is not always easy. However, some might do it, and thus, can you overfill your gas tank?

The gas pump nozzle automatically shuts off when your gas tank is full. However, you can still continue adding fuel to the point it overfills and starts dripping from the gas tank. Having an overflow is not encouraged and may have some downsides including fuel wastage. 

As much as you can overfill your gas tank, it might not always be encouraged. You need to stop fueling them the gas tank is full. Because this is something you may have done before, it is important to know what happens if you overfill your gas tank. We look at more details below to help you fuel your vehicle better.

Can You Overfill Your Gas Tank?

It is possible to get tempted to keep filling your gas tank even if the tank is clearly full. You might think that it may help save you time going to the gas station, but it is not worth it.

The idea of topping off is best avoided to prevent possible damage to your vehicle. Below is what may happen if you overfill your gas tank.

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Can You Overfill Your Gas Tank

Sometimes you may continue pumping more gas into the tank when it is full. When this happens, you risk damaging the evaporative emission control system (EVAP) in your vehicle. That is why then the pump is shut off. Stop fueling to avoid such damage to the vehicle.

All the vehicles sold in the US after 1971 had the EVAP system. The system comprises a number of charcoal canisters, valves, tubes, and sensors. This system is designed to handle the fuel vapor alone and not the liquid fuel. So, when you jam too much fuel into it, you may end up with a damaged EVAP system.

Repairing your EVAP system is not the cheapest as some can cost as high as $500. So, it is best to avoid such unnecessary repairs by simply stopping the filling process when the gas tank is full.

Here is a video of how the EVAP works

YouTube video

That is not all as you may just waste money when overfilling your gas tank. Most of the time, you may notice that the more you pump fuel in the vehicle when it is full, it flows out through a drain in the filler neck and down the vehicle’s body. Of course, you may notice fuel drops on your shoes too.

Overfilling can also lead to releasing a lot more emissions than you are supposed to. This is because overfilling a gas tank defeats the use of vapor recovery nozzles on many pumps. This leads to releasing a lot more fumes into the air. You will quickly notice that there is a strong smell of gas as you keep filling.

What To Do If Accidentally Overfill The Gas Tank

Whether it is accidental or intentional, there is a need to take proper steps to avoid possible damage to the vehicle after overfilling the gas tank. Consider following these steps to address the issue.

  • It is advisable to clean up any gas spills you may have caused while overfilling the gas tank. EPA recommends cleaning gas spills as they can lead to environmental damage. The last thing you would want to do is leave the spills on the ground without alerting the gas station owner for proper cleaning.
  • It is better to have the vehicle washed after having an overspill. The damage to the car paint might not happen immediately, but over time, it will cause a stain that is hard to remove. So, cleaning the vehicle immediately helps prevent such stains.
  • Give the vehicle a couple of minutes for the excess fuel to drain before starting the engine. Starting before that might lead to a vehicle that easily stalls even when full of fuel.
  • If the vehicle starts, you can drive it at higher RPMs for a couple of minutes. This means that it would be burning more fuel to help get it back to the normal level in the gas tank.
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These are all things you can avoid when you do not overfill the gas tank.

How To Know If You Overfill Your Gas Tank

Whenever you are filling your gas tank and it gets full, you will hear a click in the nozzle. It gives you a signal that the gas tank is full. So, the logical thing to do is stop filling the gas tank to avoid some of the issues already discussed above.

However, sometimes people may not hear this click sound and will think there is a need to keep pumping. Before they know it, there is gas spilling out of the gas tank. So, it is best to be attentive while pumping fuel. When you hear the click sound, stop fueling and you should not have any problems driving off.

Can Overfill A Gas Tank Cause A Car To Stall?

A car stalling from overfilling a gas tank is highly unlikely to happen. But it is something you cannot overrule. The problem could be that there is a problem with your fuel pump to the point the engine is not getting the right fuel amount to keep it running.

However, having a bad gas cap may make the vehicle stall. The work of the gas cap is vital for keeping debris and dirt from getting into the gas tank, but it can also help prevent gas vapors from easily escaping.

A bad gas cap may lead to having an EVAP system that does not work correctly. This is what may lead to a car stalling sometimes.

Here is how to tell you to have a bad gas cap

Is It Bad To Overfill Your Gas Tank

We already know that when you overfill your gas tank, it might lead to EVAP system damage. You would definitely not want to do that as it will be expensive to repair the whole system.

However, you may also come across many other reasons not to keep overfilling your gas tank.

Of course, you would end up with fuel leaks on the ground. Spilling fuel on the ground is simply a waste of money in addition to polluting the environment, which is something you can also avoid.

It is still a waste of money when you have to keep repairing the EVAP system when it is something you can save by not topping off the tank.

Too much fuel may also lead to wear on the spark plugs. We all know how it might be a problem running a vehicle with foul spark plugs. In addition, you may start to experience misfiring too from the engine.

Another potential problem tough not common is that you may end up with a catalytic converter failure. A failed catalytic converter means you would not pass emissions tests to keep the vehicle on the road.

Tips For Correctly Fueling Your Vehicle

Now that you know there can be potential problems with overfilling your gas tank, what is the best way of fueling the gas tank? Here are some quick tips for fueling the vehicle.

  • Always listen to the clicking sound from the pump nozzle. It means that the gas tank is full and there is no need to keep filling it.
  • You should not smoke while fueling. Gasoline is highly flammable meaning it can easily catch fire from the cigarette you are having.
  • You should also consider turning off the vehicle as it is being filled
  • In case you notice gas spills on the ground, it is best to clean it up promptly to avoid polluting the environment
  • In case you overfill the gas tank, consider giving it a few more minutes for the excess gas to drain before starting the vehicle.
  • If you have children in the car, do not allow them to come out and play around the gas station. Let them remain in the vehicle until you are done refueling.
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If you can follow the tips above and avoid overfilling the gas tank, you should not have a problem driving the vehicle each time you refuel.


Can overfilling a gas tank cause the check engine light?

Most modern vehicles are equipped with an EVAP system that keeps the gasoline vapor from escaping. Overfilling a gas tank can damage this system, which may subsequently trigger the check engine light to come on. Have the vehicle diagnosed properly to establish what is the issues for having the check engine light.

Will the gas tank leak if overfilled?

The gas pump normally shuts off the fuel flow when the gas tank is full. However, when you keep filling the vehicle, the gas will easily overflow and you end up with gas tank leaks. Other than flowing onto the car’s body, it will also flow onto your shoes. The gas smell in the atmosphere is also quite strong at this point.

The car won’t start after filling it with gas. What could be the problem?

Filling your vehicle with gas should make the vehicle run even better. However, if it does not start, there could be a problem with the fuel pump. This means that the vehicle is not getting the fuel it needs to start. Other reasons could be a dead battery, a bad starter motor, a lack of spark, and more.

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