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When it comes to our vehicles, we all want them to run smoothly. But sometimes, pesky problems like Evap system leaks can throw us off track. This type of issue typically leaves trails, such as a fuel smell.
An Evap leak is when your vehicle's Evaporative Emission Control system, which is responsible for keeping fuel vapors in check, develops a minor breach. So instead of those vapors staying where they should, they sneak into the air.
Paying attention to the signs and taking action can save you some headaches and money in the long run. So, if you catch a whiff of gasoline or that "Check Engine" light starts acting up, don't brush it off. Your Evap system might just be trying to get your attention.
The fuel tank in modern vehicles is made of molded plastic. Over time, due to heat, the plastic fuel tank seams can become brittle and develop cracks. When these cracks occur on the top side of the tank and you fill-up the gas tank, it creates pressure that forces the gas vapors to escape through the cracks in the upper part of the tank. This is what causes the smell of gas when fueling your vehicle.
The gas cap seals the gas vapors inside the gas tank filler neck to prevent leaking. But if you accidentally leave the gas cap off or the seal on it gets old or broken, those gas vapors can escape. When that happens, a warning light called the "gas cap light" will pop on the dashboard, telling you something is wrong with the gas cap.
The purge control valve has an important job: it controls how much vacuum is created in the evaporative emission system to remove the gas vapors that gather in the charcoal canister. But if the purge control valve gets stuck open while fueling the vehicle, it allows raw gas vapors to flow into the engine intake. This can flood the engine, making it difficult to start the car immediately after you've filled it with gas.
The charcoal canister is an essential part of the vehicle. It's like a container filled with special charcoal that helps to trap and hold onto the gas vapors that might leak from the gas tank. The canister is made of plastic and filled with charcoal and filters. The different parts are joined together by melting the plastic. However, these melted ligaments can develop cracks over time and with temperature changes. When that happens, the gas vapors can escape from the canister before they get absorbed by the charcoal. This is what causes the smell of gas in the garage.
The leak detection pump, a part of the vehicle's system, has an important job. It uses a unique diaphragm to check for any vapor leak in the system. This pump is connected to the charcoal canister and is sealed with a rubber seal. However, because of heat and the way the charcoal canister is made, it can sometimes get warped, making it difficult for the rubber seal to fit correctly. A leak in this seal, even a very small one, triggers the check engine light to turn on.
The filler neck on modern vehicles uses a capless system, which means it doesn't have a traditional gas cap. Instead, it has a unique mechanism that can open and close to access the fuel tank. However, as time goes by and the vehicle is used, this system can develop issues that cause gas vapors to leak out. When that happens, you might notice a gas smell near the fuel door area.
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.
The provided image proves the gas cap's issue, showing a cracked seal causing the gas cap light to illuminate.
When the customer dropped off their vehicle, they expressed concern about the gas cap light being on. They mentioned one instance where they forgot to put the gas cap on, resulting in the light coming on. They quickly remedied the situation by securing the cap and having another shop clear the light. However, the light remained active despite the gas cap being correctly placed.
During the test drive, the technician verified the presence of the gas cap light. As part of the vehicle health inspection, the technician further confirmed that the gas cap was tightly secured.
A diagnostic scan was performed to investigate the issue, revealing a code indicating a detected problem with the evaporative emission system, specifically a p0457 code.
Upon receiving authorization for additional diagnostics, the technician removed the gas cap and utilized a filler neck tester to check for any leaks in the tank and vapor system. Next, a vehicle-specific scanner was employed to assess the situation further, and the vent valve was energized to seal off the vapor system.
The pressure was applied using a smoke machine, but no leaks were detected. Finally, upon closer inspection, the technician discovered that the gas cap's seal was damaged and needed replacement.
The provided image serves as proof of the crack in the rollover valve, which is molded into the gas tank. This crack causes the strong smell of gas whenever the tank is filled to its maximum capacity.
When the customer dropped off their vehicle, they mentioned that they noticed a strong smell of gas around the car every time they filled the gas tank.
The technician didn't notice anything about the customer's concern during the test drive. However, they did observe that the check engine light was on, which could indicate a potential issue.
During the vehicle health inspection, the technician thoroughly examined the vehicle but found no signs of the customer's concern. Next, a diagnostic scan was performed to gather more information, revealing a specific code (p0442) indicating a potential leak in the evaporative emissions system.
After receiving authorization for additional diagnostics, the technician used a dedicated vehicle-specific scanner to verify the code. Next, they connected a smoke machine to the hose behind the purge control valve in the evaporative emission system.
Using the scanner's controls, they closed the vent valve and increased the flow of smoke and pressure into the vapor system. It was then discovered that a small leak originated from the top of the gas tank.
To address the issue, the technician lowered the gas tank to access the leak's location. They found the leak was coming from the rollover valve, which was molded into the gas tank. Consequently, the gas tank must be replaced to resolve the problem.
The provided image serves as evidence of the leak in the purge valve. In addition, it shows the valve with the line off while the engine is running, indicating that it leaks and needs replacing.
The customer reported a problem with their vehicle when starting it up after refueling. They noticed it takes a while to start, regardless of the outside temperature. When they turn the key, the engine cranks for an extended period before finally starting. Sometimes, it even stutters a bit before running smoothly.
During the test drive, the technician encountered no issues related to the customer's concern. However, they did notice that the check engine light was on, indicating a potential problem.
During the vehicle health inspection, the technician thoroughly checked the vehicle but found nothing related to the customer's starting issue. A diagnostic scan was performed to gather more information, revealing an error code (P0441) pointing to a possible problem with the evaporative emission control system's purge flow.
With authorization for further diagnostics, the technician disconnected the electrical connector of the purge control valve and removed the line connected to the gas tank.
They started the vehicle and observed that there was suction (manifold vacuum) on the tank side of the purge control valve. This confirmed that the purge control valve was stuck open, causing the starting problems.
A picture was taken to provide evidence of the fuel vapor leak on the charcoal canister. The image shows the area where the seam is allowing the vapors to escape.
When the customer brought their vehicle to the garage, they complained about a constant gas smell from inside.
During the test drive, the technician found nothing wrong. However, they did notice that the check engine light was active on the dashboard.
As part of the vehicle health inspection, the technician found nothing related to the customer's concern. However, they performed a scan of the vehicle's codes. They discovered two issues: P0442, which indicates a small leak in the evaporative emissions control system, and P0455, which points to a significant leak in the evaporative system emissions.
The customer authorized additional diagnostics, and the technician used a specialized scanner designed for the vehicle to confirm these codes. They then proceeded to conduct further tests by using a smoke machine.
First, they checked the purge control valve and found it functioning correctly. Next, they introduced artificial smoke into the line connected to the gas tank and used the scanner to close off the vent valve; they used a smoke machine.
This process revealed that the welded seams on the charcoal canister were leaking, causing both the smell of gas and the vapor leaks. Therefore, the charcoal canister will need to be replaced. In this case, the final proof was smoke seeping through the cracks.
A picture was taken to show where the seal between the leak detection pump and the canister was. In this case, the canister needs to be replaced.
When the customer brought their vehicle to the garage, they mentioned that the check engine light was on. They remembered that the light had come on when they accidentally left the gas cap off, but it was securely in place this time.
The technician confirmed that the check engine light was illuminated during the test drive. However, they didn't notice any other vehicle performance issues.
During the vehicle health inspection, the technician found no clues about the customer's concern. Then, however, they scanned the vehicle's codes and found a code labeled P0456, indicating a tiny leak in the evaporative emissions system.
The customer allowed additional diagnostics, and the technician used a specialized scanner designed for that specific vehicle to confirm the code. They then sealed off the vent valve using the scanner's controls and introduced a smoke machine into the vapor system.
Through this process, the technician discovered a leak between the leak detection pump and the seal on the charcoal canister. As a result, the charcoal canister and the leak detection pump must be replaced to resolve the issue.
A picture was taken to provide proof of the capless filler neck, which is the component responsible for the gas vapor leak causing the fuel smell. In addition, the image shows the part that requires replacement.
When the customer brought their vehicle to the garage, they said they could smell gas by walking by the gas filler door. However, they were unsure if this was normal because their vehicle didn't have a gas cap.
During the test drive, the technician observed nothing concerning the customer's complaint. However, they did notice that the check engine light was illuminated.
During the vehicle health inspection, the technician found no issues relating to the customer's concern. However, they scanned the vehicle's codes and found a code labeled P0442, indicating a leak in the evaporative emission system.
The customer authorized additional diagnostics, and the technician used a specialized scanner designed for that specific vehicle to confirm the code. They then connected a smoke machine to the vehicle's vapor system and used the scanner to close the vent valve.
Through this process, the technician determined that the leak originated from the capless filler neck; it was internal damage. To resolve the problem, the filler neck will need to be replaced.
Evaporative emissions control systems. Evaporative emission system leak. System leak detected. Evap canister. Emissions test.