Gasoline is very flammable, so if you smell it in or near your car, you should try to determine why before you start the engine. While there are several fairly innocuous reasons you might smell gas, the worst ones can be very dangerous. Let’s start with the “bad” causes first.
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First things first: If you smell gasoline while your engine is running, turn it off. A running engine creates very high heat in the exhaust system — and to a lesser extent, the engine itself — and you don’t want a fire to erupt. If you’re smoking, immediately put out your cigarette far from where the smell is.
Gas is pumped from the fuel tank (usually located in the back of the car) to the engine (usually in the front) through fuel lines under high pressure. With the high pressure, any small leak along the way can squirt fuel out some distance, often in a very combustible spray or mist. Particularly if this leak is in the engine compartment or near the hot exhaust system, the fuel can catch fire.
However, if you notice a gasoline odor inside your car — and you know it isn’t coming from your clothes (see below) — there’s a good chance it’s caused by a serious fuel leak in the engine compartment, and the fumes are being pumped into the interior through the car’s ventilation system.
All of these scenarios require a professional to fix. If you can’t confirm the gasoline smell is coming from a less dangerous source (see below), it’s time to call for a tow truck. Before you do, however, you can check for some potential sources of a gas smell that would largely fall under the “innocuous” category.
Causes of a Gas Smell Other Than a Leak
If you just filled your car with gas, you could be smelling gas that you got on your hands, clothes or shoes, or that ran down the side of the car or spilled on the ground. Rainbow-tinted fluid stains on the ground are likely fuel that came from your car or someone else’s. Your vehicle’s gas cap could also be loose or missing, allowing fumes to leak out. (Note that breathing gas fumes is harmful, so if there’s gas on you or inside your car, you should correct that as soon as possible.) If you’re driving in traffic, the gas smell could be coming from a nearby vehicle; you can try pulling over and parking to see if the odor goes away.
If you’re still having trouble identifying the source of the gas smell —and you’ve ruled out the worst-case scenarios — there are some additional checks you can perform:
First, look underneath your car for any signs of drips. If you see any that appear to be a clear liquid, or if you see the telltale rainbow-tinted stain or puddle on the ground under or near the car, that’s probably gas. One thing to keep in mind is that in summertime, you might have water dripping down from using the air conditioner, which is normal, but it won’t smell like gas. If you see a drip or puddle that isn’t near the engine or exhaust system, it might be tempting to drive the car to a service center, but it’s certainly safer to have it towed. However, if you don’t see any leaks, there’s one more thing you can check — though it’s a long shot.
If the engine has cooled down and the hood isn’t hot to the touch (you want to be certain there’s not already a fire burning under there), you can check to see that the engine’s oil-fill cap is in place. It’s possible for fuel to get mixed with the oil, and if the oil cap is missing (as might be the case if it wasn’t replaced after an oil change), fumes can escape and get pumped into the car’s interior through the ventilation system.
Other Potential Causes of a Gas Smell
Beyond what’s already been mentioned, there are any number of possible sources for a gas smell, but most would be best checked by a professional.
A leak in the car’s evaporative emission system, which routes gas fumes from the fuel tank to the engine to be burned, could result in a gas smell and may cause the check-engine light to illuminate on the instrument panel. Additionally, gas can sneak past an improperly sealed fuel injector or spark plug and pass through the car’s ventilation system. Other sources of a gas smell can include a leaking fuel-tank vent hose or a rich fuel mixture caused by a faulty fuel-pressure regulator or clogged air filter. While most of these aren’t serious, they’d all likely take a professional to track down and repair.
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