Why Does My Car Smell like Gas?

Question: Why Does My Car Smell Like Gas?

The last time I drove my car, I got a strong whiff of gas. The car seemed to be driving okay, but I’m nervous about driving anymore with a gas smell in my car. Is there anything benign that can make it smell like there are gas fumes in a car, or is this definitely something I shouldn’t be driving until it gets fixed?

Answer:

There are a bunch of different problems that can cause a gar to smell like gas. Some of them are serious, and others aren’t, so it’s important to figure out what’s going on as soon as possible. You may just have a loose gas cap, or fumes could have gotten inside when you stopped at a gas station, or there could actually be a leak somewhere that might eventually result in a fire.

The most common causes for a car to smell like gas include:

  1. External source (i.e. a gas station or another car)
  2. A missing or loose gas cap
  3. Leaking injector, carburetor or throttle body
  4. Other leaks (fuel tank, fuel line, filter, etc)
  5. Problem with the charcoal canister or return line

How Gas Fumes Get in a Car

Gasoline is an aromatic hydrocarbon with an extremely strong odor that can linger for a very long time. With that in mind, it’s possible to have your car smell like gas when the problem isn’t your car at all.

car smells like gas from gas station

Image courtesy digitonin, via Flickr (Creative Commons 2.0)

If you stopped fuel up at around the same time your car started to smell like gas, the culprit may have been a spill at the gas station. Since gas fumes are so strong, it’s possible that the smell got in your car, or clung to you, through no fault of your own.

The easiest way to tell if the problem is your car, or some external source, is to roll down the windows—if the weather permits—and take another sniff after some time as passed. If the gas smell dissipates, and it doesn’t come back, then you were probably just smelling somebody else’s leftovers.

Should the gas smell linger in your car, despite the open windows, or if it comes back, then you’ll want to move on to other possibilities.

Checking Your Gas Cap

While a gas cap isn’t the most common cause of gas fumes getting inside a car, it is the easiest and fastest thing to check. If you find that the cap is missing, or if it’s loose, then that may be the problem. You can either tighten it, or replace it with a new cap from your local parts store, and that may fix the problem.

With some gas caps, it’s hard to tell whether or not it’s tight. You can tell whether or not you have this type of cap, because they make a clicking noise when you turn them. This type of cap will never feel tight, but if it’s clicking, that’s the audible clue that it’s tight.

In some cases, that type of gas cap will make the clicking sound, indicating that it’s tight, even though there’s a problem with the cap that prevents it from sealing properly. This is usually only an issue with vehicles that have an evaporative emissions system, and the computer in those situations will generally throw an evaporative emissions code if the gas cap isn’t sealing properly.

Checking for Leaky Carburetors and Injectors

The next step in figuring out why your car smells like gas is to pop the hood and take a look. You won’t always be able to identify this type of leak with a visual inspection, but you might be lucky. So if you notice wetness around a carburetor fuel line, or a fuel injector in a newer car, that might be the problem.

If you smell gas from your carburetor, it could be a leak or normal operation. | Image courtesy psiho.child, via Flickr (Creative Commons 2.0)

It’s also important to note that if you do drive an older car with a carburetor, it can be perfectly normal to smell gas after you shut the engine off. This is due to residual fuel left in the float bowl, and it should dissipate normally. So if you only notice the smell after you shut the car off, and it goes away after a while, that may be the problem.

Checking for Other Fuel Leaks

Other places to check for fuel leaks include the gas tank, fuel lines, and filter. These types of repairs may be out of the realm of do-it-yourself fixes for many people, but you can often narrow down the source of the problem with some cardboard or drip pans.

It doesn’t take a lot of gas to spread out into a rainbow on wet pavement. | Image courtesy CJ Sorg, via Flickr (Creative Commons 2.0)

If you ever notice a rainbow of color on the ground after you move your car, that could be the result of a fuel leak. Even a tiny amount of gas on a wet driveway or road surface can cause this phenomenon, so you’ll want to set cardboard or drip pans under the vehicle all the way from the gas tank to the engine.

Most cars use a combination of metal fuel lines and rubber fuel hoses. These are usually fastened together by hose clamps or compression fittings, and metal fuel lines often connect to fuel filters, carburetors and injector rails via flare fittings and banjo fittings. Each of these types of connections can fail, so these are all common sources of fuel leaks.

Gas Smells from Charcoal Canisters and Evaporative Emissions

Gas likes to evaporate, and when it evaporates, it smells. In older cars, this evaporation process was allowed to proceed unchecked, but newer vehicles are equipped with evaporative emissions systems.

One purpose of an evaporative emissions system is to trap gas fumes generated in the gas tank in a charcoal canister. These fumes are then purged periodically and burned along with the regular air/fuel mixture in the engine.

If a charcoal canister develops a leak, or any of the evaporative emissions system lines leak, you can end up smelling gas fumes in your car. This isn’t the type of thing that you can usually check with a basic visual inspection, but evaporative emissions system problems usually do cause the check engine light to come on. So if your check engine light is on at the same time you smell gas in your car, that may be the problem.



JD Laukkonen

JD Laukkonen turned wrenches in the north end of Seattle for a decade, so he's no stranger to the inner workings of modern automobiles. He has worked as a freelance writer since closing his shop in 2007, and he currently covers automotive technology for Lifewire.com.

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