What To Do When You Overfill Your Gas Tank: Four Easy Steps

What to do when you overfill your gas tank can prevent many bad things, including a risk of fire and engine damage. It would be best to clean up any mess caused by the overflow, wait for the excess fuel at the filler tank to filter down, and then start the engine and drive at high RPMs.

What To Do When You Overfill Your Gas Tank

Find the detailed guide below, including why you may need to contact a mechanic. In addition, we have discussed beneficial practices to observe when at the gas station to prevent filling up excessively and ensure safety.

How To Resolve an Overfilled Car Gas Tank Problem?

To resolve an overfilled car gas tank problem, clean up any messes immediately. Wait a few minutes for the excess fuel in the filler tank to filter down before starting the engine. When it’s safe, drive at high RPMs to burn the extra fuel in the tank.

As you fill up your gas tank at the gas station, the car’s fuel system should automatically shut off as the tank gets full. However, anyone can coincidentally overfill the tank. And as the tank begins to overfull, the gas will accumulate in the filler neck. When you stop pumping, the gas will filter into the tank as it compresses.

Anything that doesn’t fit into the tank will drip into the EVAP system, block the vapor intake hole, get sucked into, and damage the charcoal canister. Moreover, a gas tank leak can lead to wear on other critical engine components, such as spark plugs. 

As a result, you may notice engine performance issues, including misfire and illuminated check engine light. In the worst-case scenario, gas overflow or leak can lead to a catalytic converter failure.

Even if you only require replacing the EVAP canister, you might face a repair bill of at least $250, depending on your car model. Overfilling your fuel tank could also spill fuel on your hands, the ground, or the car itself. Fuel is highly flammable, and spillage means an increased risk of fire. When gas overflows and spills on the floor, it becomes a waste of money and an environmental hazard.

Listening to that shut-off mechanism when fueling would be best to avoid excessive fill-up. But as mentioned, accidental overfill can happen, and we’ve already mentioned practical tricks to fix the error and return the tank to its corrected filled state.

Let’s discuss that in detail:

1. Clean It Up

The most important thing to do if you’ve accidentally overfilled gas tank is to clean up the mess created by the overflow. As mentioned, according to the EPA, gasoline spills are harmful to our environment. So, it would be best not to leave it spilled on the ground. If it gets on your car, wipe it with a cloth or towel to prevent damage to the vehicle’s paint job.

Cleaning Up Gas Tank

We’ve already discussed a few things about what happens if you overfill your gas tank once. But for those wondering whether overfilling the tank can cause a car explode, overfilled gas tank explosion is unlikely.

In most cases, an overfilled tank will leak into the EVAP system. In addition, overflows could lead to a leak, and leaking fuel can trigger a fire. Thus, it’s essential to clean up the mess immediately.

2. Wait Before Starting the Engine

You should not start a car with an overfull gas tank. So, if the fuel is in the filler tank, wait a few minutes for the fuel to filter down. As stated, gasoline is highly flammable, and a spark can lead to a disaster.

If the engine is running, which shouldn’t be, turn it off and wait for the excess fuel to fill the tank. The process takes little time. Within 2-5 minutes, some of the gasoline in the neck will have evaporated. You can use this time to clean any mess you made around the fuel pump but forgot to clean in Step 1 above.

Only when all the fuel has filtered into the tank and you’ve cleaned up the spillages will it be safe to turn on the engine again. If that doesn’t happen, it would be wise to have the car towed.

3. Drive at High RPM if It’s Safe

Unfortunately, it’s not possible to siphon excess gas off the tank. Your best bet is to try to burn the fuel for the tank to return to normal. Therefore, if starting the engine is safe, drive the car at high RPMs. Revving up the engine allows you to burn off the excess fuel in the tank and fix the overfill situation.

In other words, the move will leave you with a moderately filled tank. Many have asked, “Overfill gas tank car won’t start; what could be the problem?” Many things can cause a vehicle not to start or require multiple tries to start after fueling, but the main culprit is usually a faulty purge valve. In any car, different sensors and solenoids handle the gas pressure within the fuel system.

Driving at High Rpm

Overfilling the tank can force excess gas into these systems, causing problems in their seals. That may not only cause the engine not to start but also sputter after starting and reduce engine power output. In fact, many have found themselves in an “overfilling gas tank check engine light” situation.

Other reasons why a car won’t start after fueling may be a failing battery or a loose connection. It could also result from a clogged fuel filter or problems with your gas pump. If your car fails to start after fueling and you can’t figure out the cause, seek the help of a professional immediately.

4. Contact a Mechanic

If your car doesn’t fill right after pulling away from the fuel pump, it would be best to have a mechanic examine it. The cause could be the gas overfilling or an existing issue. Someone asked, “If you overfill your gas tank will it leak?” The answer is yes!

As explained above, the overfilled tank will mostly leak into the EVAP system. Also, the increased pressure could cause the tank to leak, leading to problems within the engine. Timely repairs on any damage can help prevent failures that require costly repairs. Remember to fill the tank correctly in the future.

How To Ensure Safety While Fueling Your Car?

To ensure safety while fueling your car, always turn off the engine when you pull up at the gas station. Be attentive to avoid gas tank overflows and avoid anything that could trigger fire, such as a matchstick. If you have children, let them remain in the car.

At this point, you contend that overfilling your gas tank is bad. However, there are many other things people do while at the gas pumps that are as harmful. You must observe the exemplary filling practices as explained above to ensure safety.

Let’s discuss the detail:

  • Always Turn off the Engine

Once you pull up at the fuel station, switch off the engine before you or an attendant starts fueling your vehicle. Killing the engine is a primary safety measure that you should never forget. An engine at work involves a process of combustion, which means there are sparks of fire.

Turning off Car Engine

Diesel and petrol are highly flammable. It only takes a spark to cause a significant fire leading to a disaster. So, always fuel while the engine is off as a precaution.

  • Be Attentive To Avoid Overfilling

One way to know how to not overfill gas tank is to be attentive. When the pump automatically turns off, stop fueling and put the pump back in its place. Avoid the temptation to top off to the nearest dollar.

You already know what to do if you accidentally fill the tank excessively: clean up the messes and wait a few minutes before starting the engine. However, being attentive will prevent you from overfilling the tank in the first place.

For anyone wondering how to know if you overfill your gas tank, the engine malfunction light may come on as you drive. That’s particularly so if the excess fuel causes the engine to run rich. As mentioned, you should contact a mechanic as soon as possible.

  • Avoid Potential Fire Triggers

As you already know, fuel is a highly combustible fluid, and a fueling station may have tons and tons of it. That poses a tremendous threat as the slightest spark can turn the place into an inferno. Avoiding potential fire triggers, such as a matchstick or lighter, is an obvious precaution. That is a critical thing to remember, especially for a chain smoker.

Potential Car Fire Triggers

Keep anything that could trigger fire away, including magnifying glass or mobile phone. Mobile devices may heat up quickly on a sunny day, explode and result in a chain reaction that leads to a major fire incident. You should avoid talking on a mobile at a fuel station.

  • Let the Children Remain in the Car

Some people allow kids to pump gas, which is wrong. Let them remain in the vehicle for their own safety. As other vehicles maneuver at the gas station, the place can quickly become dangerous. As mentioned, the high volumes of stored fuel make the area risky enough.

In addition to these guidelines, following the rules posted at the various spots at the gas station is essential. Ensure you read any signs carefully to remain safe throughout the fueling session. Also, beware of the surroundings and your belongings to avoid theft.

Avoid being forgetful, for example, not picking up your credit card after making payments. Although that may not pose an immediate danger, forgetting to close or tighten the fuel cap can be risky.

Frequently Asked Questions

What Amount of Fuel Is a Full Tank in a Car?

The amount of fuel that is a full tank in a car varies depending on the model and production year. In other words, different vehicles have varying fuel tank sizes. On average, small cars carry about 12 gallons (45 liters), while larger ones have 15 gallons (56 liters) or more.

What Causes a Car To Shake After Fueling?

The causes of a car shaking after fueling are common issues in the EVAP emissions system. Specifically, shaking can occur if the purge valve malfunctions. For example, if the valve is open during the fueling, it can allow excess fuel vapor into the engine, leading to the shaking issue.

How Long Will Gas in a Car’s Tank Last?

The gas in a car’s tank will last three to five months, and the exact time depends on the fuel type. Regular gasoline has a lifespan of six months, while diesel can remain usable for twelve months. Avoid a full tank if you don’t drive often and over long distances.

Can Overfilling Your Gas Tank Lead to Impound Fees?

Overfilling your gas tank might not directly lead to impound fees. However, there are ways to waive impound fees effectively if your vehicle does get impounded for other reasons. It’s important to inquire about potential waivers or discounts available, provide all necessary documentation, and follow the impound release processes diligently.


In our “What to do when you overfill your gas tank” guide above, we’ve discussed four steps to fix the problem. Here’s the summary:

  • Overfilling gas can have serious consequences, and you should always avoid it.
  • If it happens accidentally, the first action is to clean the mess up and never start the engine until it’s safe.
  • Revving up the engine allows it to quickly burn excess fuel and bring it to proper levels in the tank.
  • Being attentive at the gas station can help you steer clear of overfilling gas.
  • Always fuel your car while the engine is off as a safety precaution.

You’re now equipped with enough information to fix your gas overfill situation and avoid getting into the same again. So, do it, and remember to call an expert to check your engine if you notice anything odd.


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