Gas is highly volatile thanks to its low flashpoint. Automakers invest in sealed and vented tanks to ensure that all the gas and fumes stay inside the fuel system as much as possible. Governments also have legislation limiting gasoline (petrol) handling, ensuring you can’t carry it anyhow.
If everything is perfect, you should never smell gas – unless you are pumping it. A car that smells like gas before starting or when driving is most probably leaking. We will help you find the leak ASAP before it goes up in flames.
A Gas Smell That Goes Away Once You Start Driving
If the smell vanishes when you start driving, chances are the flowing air flows it away, or you have driven away from a hotspot where the gas had leaked enough to be noticed. Here are some possible scenarios:
You Have a Slow Leak Somewhere in the Fuel System
This is a plausible explanation, especially if you notice the smell the most after parking your vehicle for a while.
A slow leak that’s been dripping fuel over time should create a puddle big enough to make the outside and interior of the vehicle smell like gas.
The smell will then disappear when you turn on the engine and drive off because:
- You will have left the place where the fuel had time to saturate the air and start smelling
- When driving, the wind blows away from you, carrying off any fresh gas smell. You won’t notice it.
A Loose, Faulty, or Missing Gas Cap
A good gas cap makes a perfect seal with the fuel tank spout when screwed in. This is crucial because gas fumes will escape through openings left by a loose, faulty or missing gas cap.
Most cars will through a check engine light if your gas cap is loose or faulty. If yours doesn’t, and you still smell gas:
- Open the fuel filler door.
- Note if the gas smell intensifies when next to the cap. If they do, the cap could be the problem.
- If it is missing, find a replacement.
- If it is present, open it, alight the thread properly and close it until it clicks thrice.
- If you are still getting a strong gas smell at the cap after this, consider getting a replacement or having a professional look at it. It could be faulty.
A Recent Fuel Spill On or Around the Car
If you recently filled up your car and had some gas slosh around, that could give your car that scary smell.
However, since gas is very volatile, the smell should be gone within hours once all the fuel evaporates.
Spills often happen when you are inattentive when filling up or using an inappropriate canister to bring fuel to your stuck vehicle.
Under ideal conditions, you should never spill fuel anywhere. Any tiny spark can ignite spilt gasoline. In case you see a spill on or around your vehicle:
- Soak up the fuel with a clean rag or towel and transfer the rags somewhere else
- Use a towel soaked in 50% hot water and 50% vinegar to clean the remaining fuel
- Leave the car out in the open to ventilate
- If the leak is on the floor, you can use sand or cat litter to soak it up before sweeping the sand or cat litter for disposal.
Once again, if you are dealing with a spill under or on the car’s exterior, the smell will vanish once you start driving and airflow pushes it away. The smell will only persist if the spill is inside the car.
A Faulty or Older Evap System
An Evap system is an addition to the fuel storage system that handles vapors created within the fuel tank. Instead of venting the fumes into the environment like the old cars, the Evap system holds these fumes in a charcoal canister and eventually dumps them into the intake manifold when you turn the engine on.
A clogged or flooded charcoal canister could render the system inefficient, forcing the fumes out into the open or into spots where they can slowly seep into the environment.
If you own an older vehicle that didn’t have an elaborate evap system that captures and combusts the vapor, chances are you are venting it into the environment. This increases the probability of noting the smell if you leave your vehicle parked in a hot and badly ventilated place.
A Smell That Goes Away as Soon As You Let the Engine Run
If you have an older carburated engine, you could get a lingering fuel smell because a carb could keep some fuel in the float bowl even with the car off.
While some carburated cars made after the 80s used systems that drained the float bowl, very few units have working drainage and the accompanying evap system to take all the gas and fumes back to the fuel tank.
In a carburetor, leaving some fuel in the float bottle was a good idea since it meant the car will crank as soon you turn the key as there is some fuel in it already. The alternative would have been a longer crank or waiting after turning the car on for a second or two so that the fuel pump delivers fresh fuel to the carb.
ProTip: Pop the hood and inspect your carburetor. The gas smell should get strong when you open the hood and even stronger when you move closer to the carburetor.
If you have a carburetor on your engine and find the smell every time you park, figure out if it disappears after turning the engine on:
- Turn on the car and drive it to a different spot
- Let it idle for a minute or two
- If you can no longer pick the scent from the hood or carburetor, the fuel in the float bowl was the problem.
If the fuel smell persists when driving or immediately after stopping, you have a serious fuel leak somewhere. Have the entire fuel system, from the fuel pump to the fuel lines, high-pressure pump, and injectors inspected.
Your Car is Running Too Rich When Cold
An engine that is running rich or isn’t completely burning injected fuel will have an exhaust that smells like gas since all that unburnt gas will be in the exhaust. If the smell goes away once the engine warms up, it could mean that the engine is no longer running rich, or it is now burning all the injected fuel.
If you can localize the smell to the exhaust, you should start investigating things that could cause incomplete combustion or a rich air-fuel mix like:
- Faulty spark plugs
- Faulty fuel injectors
- Faulty ignition coils
- A bad idle position setting that isn’t letting in enough air for complete combustion at idle
- A faulty intake temperature sensor
- A damaged fuel pressure regulator
Luckily, you will get a check engine light when your engine runs rich. An OBDII scan should help you identify and narrow down the problem making a fix simpler.
ProTip: An engine that runs rich will also give you a whiff of gas smell at the exhaust. This might not go away after running the engine for a while. You might perceive it less as you drive, but it will still be there.
Can I Drive a Car that Smells Like Gas?
Driving a car that smells like gas is lethal. Gas is highly flammable – especially if it has vaporized. If you can smell it, it means it has already vaporized. This gas vapor can ignite, catch fire or explode if something sparks close to it.
This could be anything from sparking contacts of a solenoid or electrical system to someone lighting a cigarette nearby.
If your car smells like gas, move it into an open and well-ventilated space, then do a thorough inspection to find out where the smell comes from. Finding and fixing the problem is paramount. Don’t spare any expense. The stakes are very high.