Quick Tips About Overfilling Gas Tank
- Pumping too much gas into your tank is unsafe and not good for your car.
- The potential for damage should overshadow any perceived benefit to topping off.
- Pay attention while refueling, and stop pumping when the nozzle automatically shuts off.
Overfilling a gas tank can lead to problems with the car, including difficulty starting or having the check engine light come on because the emissions system is impaired. Too much gas in your tank can saturate the charcoal canister, promote purge valve failure, and cause solenoid damage.
Adding more fuel after the pump “clicks” or shuts off to indicate a full tank is a habit that can cost you hundreds of dollars in repairs down the road. Keep reading to learn more about putting too much gas in your tank.
- Should You Top Off?
- Stop Pumping When the Pump Shuts Off
- It’s Not Worth Adding More Gas
- What to Do If You Overfill
Should You Top Off Your Car’s Gas Tank?
Some motorists try to pump as much fuel as possible into their gas tanks to get a few more miles of driving between fill-ups. Others add more to a full tank because they like the simplicity of paying an even dollar amount. No matter the reason, topping off at the pump may cause spills, is unsafe, and is not good for your car. Our advice: Stop pumping when the nozzle handle clicks off.
RELATED: What Kind of Gas Does My Car Take?
Never Add More Fuel After the Gas Pump Clicks
A gas pump automatically stops pumping when sensors indicate the car’s tank is full. Sure, some extra space is in the tank, but that allows room for expansion. Adding more gas and having the pump click a second or third time can overwhelm the evaporative system or cause a leak.
Overfilling the gas tank can ruin the car’s evaporative emission control system. The EVAP system prevents gasoline fumes from escaping from the tank and fuel lines into the atmosphere. While the EVAP canister is efficient at filtering gasoline vapor, it’s not designed for liquid gasoline coming from an overfilled gas tank.
The potential negative effects on the vehicle, the environment, and your wallet should overshadow any benefit of forcing another half gallon of gas into your tank.
It’s Not Worth Pumping Topping Off Tank
So, is it bad to overfill your gas tank? It certainly isn’t good, and you should prevent it from happening to help avoid damage and costly repairs to critical components in your vehicle. Whatever reason or excuse you have for regularly topping off your gas tank after the pump automatically stops — “I can drive 13 miles with the extra gas I squeezed in!” or “I’m glad I rounded up to the next dollar and not forced to carry that 38 cents in change!” — is not worth the risk of paying about $300 or more to replace an EVAP charcoal canister.
MORE: Should You Get Your Oil Changes at a Dealership?
What to Do When You Overfill Your Gas Tank
Don’t panic if fuel overflowed when you were pumping gas. A one-time accident isn’t likely to destroy your fuel system immediately. And accidents do happen. I was filling my Chrysler Pacifica using a pump with a faulty air pressure sensor in the handle (or I didn’t have the nozzle fully inserted into the filler pipe). The gas flow didn’t stop until I released the trigger after hearing liquid pouring from the tank opening.
When that happens to you, clean up the mess you made on the side of your car and the ground. Then, take a drive to burn some gas. Meanwhile, remind yourself to follow fundamental guidelines next time to prevent overfilling gas tanks:
- Stay next to the pump in case it doesn’t automatically shut off.
- Pay attention while filling up your tank.
- Stop pumping when the handle clicks off.
- Do not “top off” when refueling.
They say there are two kinds of people…those that can learn from others misfortunes and those that must learn the “ hard way”. I seem to be the latter, but hopefully some of you are the former. The authors are correct about not topping off and I can tell you a true story that made me a believer.
The EVAP system is designed to store and then burn unused fuel and vapors rather than allow it to be released into the environment. Raw fuel can be added to the EVAP storage canister when you overtop…which is not good…and in some cases like mine..can be quite bad! For a month I had been getting a check engine code for the EVAP system on my 4wd crew cab truck. I had been looking for the cause of the engine code but the problem (a cracked plastic EVAP purge line) was difficult to spot as it was behind the engine near the firewall. After filling up, I was towing a large boat to the Pacific Ocean in the middle of “Nowhere, Northern California”. As designed, the EVAP system operated to burn the impounded canister fuel and fumes. In this case, the purged EVAP air-fuel mixture didn’t get burned by the engine but instead, the mixture leaked out of the cracked plastic line very near my EXTREMELY HOT EXHAUST.
Does anyone remember the 3 things required to support combustion? Fuel? Check. Oxygen? Check. Heat source/ignition source? Check. One moment I was dreaming of catching King Salmon and the next I had a fire under my hood…. right at the…you guessed it….firewall (ever wonder about the names of things??) This brief fire was hot enough to melt a cooling line and I let out exclamations similar to “MAYDAY..MAYDAY!!” (but with different letters) as I came in for an emergency landing. I was lucky to have a turnout almost immediately and I shutdown with the engine sputtering and a cloud of steam billowing from under the hood. Thoughts of catching King Salmon on the open ocean were rapidly fading. I was actually fortunate the cooling line melted when it did as the steam caused by the antifreeze hitting my exhaust manifold didn’t do the fire any good. The entire episode was over in about 10 unnecessary seconds.
The moral of the story?
1) Not all check engine lights and EVAP leaks are created equal! A loose gas cap can throw an EVAP code but an EVAP “purge line leak” at your firewall can be a much more serious issue.
2) As the article states, don’t overtop! It’s not good for your vehicle, the environment, or your bank account!
Thanks for sharing that story. I’m glad you were able to get off the road. The outcome could have been a lot worse.