(866) 678-8505
Issues 0
Car
Shop
Select Date
Your Request for Help
Select your make
Select auto repair shop
Your preferred contact Info
Issues
Symptoms:
Home / Symptoms / Car Leaking Gas

Hey, Why is My Car Leaking Gas?

If you are short on time and want to fast-track the process to professional help, click
Four common causes for a vehicle Leaking Gas and their related parts.
Gas in your vehicle's gas tank should not be able to be seen or smelled. If liquid or vapor gas is leaking out of the vehicle, there is a huge risk of fire danger. The other danger is to the atmosphere as greenhouse gasses are produced from gas fumes. If you see or smell gasoline, be very cautious and seek professional help to remedy the situation.

Is Your Car Leaking Gas?

The gas leak is commonly caused by a crack or looseness in the fuel tank. However, it can also be caused by a misplaced gas cap, faulty fuel injectors, damaged fuel lines, valve leaks, or even a broken sensor allowing fuel leaks.

Gas powers our vehicles because of its flammability. So, when it leaks, it reasonably causes concerns. But, in addition to the fire hazard, gas vapors are toxic and harmful to the environment.

A vehicle's "check engine light" may indicate a fuel leak, and the "gas cap light" ensures your fuel system is sealed. Remember, this pressurized, sealed part is designed to safely contain fuel and harmful vapors.

Gas leaks are easy to detect since they strongly smell and leave puddles under your vehicle. But, sadly, gas leaks don't only put the driver in danger but everyone around the car as well.

Let's Get To The Bottom Of It!

Do you have gas leaking under your vehicle wherever you park?

You might also smell gas fumes while driving or notice decreased fuel economy.

Fuel tanks are designed to reduce pollution by sealing fuel and vapors inside. But unfortunately, many modern vehicles have flexible plastic tanks that can weather, developing cracks in the seams. If this happens, a fuel puddle can build up under the car wherever it's parked.

Do you see a puddle of gasoline under your car when idling?

You may also smell gas fumes while parked or see a puddle of clear fluid under your car that changes colors on the surface.

The fuel line on a modern vehicle is a rigid, high-pressure plastic with quick-disconnect fittings that are formed on both ends. It's designed to carry the fuel from the gas tank to the injector rail. If the plastic line develops a crack or the rubber seals in the quick disconnects degrade, the line will start leaking as the fuel pump runs. Since the pump is idle, you'll notice gasoline puddling underneath the vehicle.

Do you smell gas when you are driving down the road?

You might also notice that the engine is difficult to start or the motor oil seems thin.

The fuel injectors are triggered electronically to open and spray atomized fuel into the intake. Some O-rings seal the injector to the intake and the fuel rail. These O-rings are rubber and can become brittle and crack over time. These seals start to leak during engine operation. Air pushed through the vehicle by the engine makes the gas smell more noticeable while driving.

Is your "gas cap light" on?

You may smell gas when opening the hood or have trouble starting the engine after fueling up.

The gas cap is sealed to the filter neck with an O-ring to prevent the escape of harmful vapors. However, these seals are rubber, which can rigidify and crack over time. When these cracks develop, the evaporative emission system cannot form a vacuum to hold pressure in the fuel system. This failure turns the gas cap light on.

Is your "check engine light" on?

You might also see a puddle of gasoline under the vehicle or smell gas fumes while driving.

The fuel pressure sensor on top of the fuel pump module detects pressure in the fuel tank to verify that no fuel vapor leaks into the atmosphere. If you lose pressure because of a seal leak, the "check engine light" will come on.

Is your vehicle hard to start after filling up with gas?

The engine might also be hard to start at other times, and you might smell gas when opening the hood.

The purge control valve is designed to stay closed, only occasionally opening to evacuate gas fumes accumulated in the charcoal canister. This helps to dry out the canister. However, if this valve fails and sticks open, adding fuel to the tank forces gas fumes into the intake, flooding the engine. You will experience this issue by struggling to start your car after getting gas.

Find Professional Help

Please select your vehicle's brand and location so we can locate the best professional help for you
If you are a shop owner and sick of business directories that are based on the cost of repair, AutoTechIQ is for you. If your customers receive Digital Inspection results then AutoTechIQ is definitely for you. Check out the certification page or how to rank in your area.

Vehicle Health Inspection Proof

Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.

Fuel tank leaking

The proof image shows gas dripping off of the leaking fuel tank.

A customer dropped off their vehicle after noticing a puddle of clear liquid underneath it in their garage. They also reported a powerful smell of gas. They checked the gas cap and ensured it was tight before bringing the car in.

The technician did not notice anything about the customer's concerns on the test drive.

During the vehicle health inspection, the technician lifted the vehicle and saw that its gas tank was wet and smelled like fuel; these elements could indicate a fuel leak. To further investigate the issue, the customer authorized the shop to perform additional tests to confirm a fuel leak suspicion.

The mechanic pressurized the fuel system with a smoke machine and dropped the gas tank low enough to check the top for leaks. They found the leak and verified that it was coming from the seam on the side. Unfortunately, the gas tank will need to be replaced.

Fuel line leaking

The proof image shows a leaking fuel line at the seam on the fuel pump.

A customer dropped off their vehicle after noticing something odd. First, the car left a smell of gas in the garage the night before. Then, the following day, the gas smell was gone, but when they started the car and left it idling to warm up in the garage, a puddle of gas formed underneath the vehicle.So they shut the car off and had it towed.

Once it arrived, the technician started the vehicle and drove it directly into the service bay. During the vehicle health inspection, the technician noticed gas dripping off the gas tank while the car was running. To further investigate the issue, the customer approved additional tests.

The mechanic lowered the gas tank enough to see the top of the tank. Then, they asked for an assistant to get in the vehicle and cycle the key off and on while they inspected the fuel system.

The technician verifies gas leaks from the fuel line attached to the pump. The fuel lines' assembly will need to be replaced.

Fuel injector leaking

The proof image shows a spot of the gas leak between the rail and the injector.

A customer dropped off their vehicle concerned about smelling gas while driving. They reported they did not see any gas puddling underneath the car after parking or running it. However, they smelled gas when they warmed the vehicle in the garage.

On the test drive, the technician verified a gas smell while driving.

During the vehicle health inspection, the shop noticed that the number one fuel injector was wet.

The mechanic started the car and dried the injector with compressed air to verify where the leak was coming from. They confirmed that the leak came from the seal between the injector and the injector rail.

The shop recommended replacing all injector seals to prevent more leaking since they are all the same age.

Gas cap leaking

The proof image shows the cracks in the gas cap seal that allow gas vapors to escape.

A customer dropped off their vehicle because the "gas cap light" turned on and off. They reported repeatedly tightening the gas cap and screwing it on with a ratchet. Even after tightening, the "gas cap light" kept flashing.

On the test drive, the technician verified that the "gas cap light" was on the dashboard.

During the vehicle health inspection, the mechanic noted that the gas cap had cracks in the O-ring seal. The technician did a vehicle code scan and found an evaporative emission system leak. To further investigate the issue, the customer approved additional tests.

The mechanic performed a smoke test on the evaporative system and found no leaks. The gas cap is the only part related to the issue and needs replacement.

Fuel pressure sensor leaking

The proof image shows fuel leaking from the car's fuel tank pressure sensor seal.

A customer dropped off their vehicle after driving with the "check engine light" on for about a month. Note that the "check engine light" must be turned off for the vehicle to pass an emissions check.

The technician performed a test drive and noted the "check engine light" on the dashboard.

During the vehicle health inspection, the shop noticed nothing related to the customer's concerns. Then, they ran a vehicle code scan and found an evaporative emissions control system pressure sensor range/performance problem. To further investigate the issue, the customer approved additional tests.

The technician performed a smoke test on the evaporative emission system. They detected smoke coming from the top of the gas tank. Further testing was authorized, and they removed the entire gas tank.

After pressurizing the gas tank, the technician noticed a leak on the tank's fuel pressure sensor. They removed the pressure sensor and found that gas had intruded into the sensor and caused it to fail. The shop recommended replacing the fuel pressure sensor and seal.

Purge control valve leaking

The proof image shows where to apply the vacuum to test if it holds when attempting to verify that the purge control valve has failed.

A customer dropped off their vehicle after it had trouble starting. They noticed that starting it with a full fuel tank is always troubling.

The technician did not notice anything about the customer's concerns on the test drive. Then, however, they saw the "check engine light" on the dashboard.

During the vehicle health inspection, the technician found nothing related to the problem. Then, the mechanic did a vehicle code scan and detected an evaporative emissions system leak. To further investigate the issue, the customer approved additional tests.

The technician performed a smoke test on the evaporative emission system and found that the system wasn't holding pressure. They didn't notice any smoke from the lines or the tank.

The mechanic removed the purge control solenoid and tested it with a vacuum pump. Unfortunately, the tests proved that the valve was stuck open. Therefore, the purge control valve needs to be replaced.

Typical Fixes to Address the Cause(s)

The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.

Sometimes a problem is more challenging to describe than it initially looked like. If you are not sure your problem is described by this article, please find below similar vehicle symptoms, which might describe better the issue you are experiencing.

Vehicle Symptoms

Below are just a few examples of typical Symptoms and Fixes your car might be experiencing

Four common causes for a vehicle Leaking Oil and their related parts.

Hey, Why is My Car Leaking Oil?

Itrsquos leaking oil because there might be sealing issues in the oil ...
Four common causes for a leaking coolant from the vehicle and their related parts.

Hey, Why is My Car Leaking Coolant?

The coolant leak is commonly caused by a crack in the radiator the hea...
Four common causes for leaking water from the vehicle and their related parts.

Hey, Why is My Car Leaking Water?

The water leak is caused by condensation in the air conditioning syste...
Four common causes for a vehicle leaking red fluid and their related parts.

Hey, Why is There Red Fluid Leaking from My Car?

The red fluid leak probably comes from the transmission or hydraulic p...
Four common causes for a vehicle leaking red fluid and their related parts.

Hey, Why Is My Car Battery Leaking?

The battery can leak by banging around if its holddown rack is faulty ...
Four common causes for a vehicle EVAP system leak and their related parts.

Hey, Why Is My Evap System Leaking?

When it comes to our vehicles we all want them to run smoothly But som...
Four common causes for a vehicle Radiator Leaking and their related parts.

Hey, Why Is My Radiator Leaking?

A radiator leak is commonly caused by a loosebroken radiator cap damag...
Four common causes for a vehicle with a Power Steering Leak and their related parts.

Hey, Why Is My Power Steering Fluid Leaking?

A power steering fluid leak is commonly caused by a faulty sealing in ...
Four common causes for a pink fluid leaking from the vehicle and their related parts.

Hey, Why Is Pink Fluid Leaking From My Car?

A pink fluid leak is commonly caused by a seep in the transmission pow...

Typical Fixes Pages