Are you having a problem with your GMC Yukon not taking gas when you bring it in for gas and do you want to know what to do about it? You’ve come to the right place, for we have researched this problem and have the answer for you.
A problem with the EVAP system of your Yukon may prevent your vehicle from taking in gas. This is likely a problem with the purge function of the EVAP system. This can be fixed by a professional mechanic, but this can be too complex for a DIY mechanic.
In this article, you'll learn more about the EVAP system of your car so you can better understand what the system does for your Yukon. We'll also look at other potential causes of this problem. Read on to learn more!
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What is the EVAP system?
The EVAP system or the Evaporative Emission Control System has several functions that manage the fuel vapors of your GMC Yukon.
The hydrocarbon pollution from your car doesn’t come only from the exhaust. Fresh fuel that goes into the gasoline tank produces fumes round-the-clock that add to the hydrocarbon pollutants that your vehicle produces. It also produces pollution whether your car is running or not.
Thus, in the 1970s, the EVAP system became a requirement for all vehicles that use gasoline as fuel.
A typical EVAP system consists of the fuel tank, fuel tank gas cap, vapor storage (a container full of charcoal) canister, valves, and hoses. The fuel tank has a vent that collects fuel vapors and passes them to the vapor storage canister. The charcoal in the storage canister traps the vapor in the canister.
Once you start your GMC Yukon, the PCM (Powertrain Control Module—the brain of your car) waits for your engine to reach a certain temperature. The PCM will then open the purge valve to release the vapors into the intake manifold of your engine.
Your engine will then burn the vapors as a part of the air and fuel mix while you drive your Yukon.
Modern EVAP systems monitor the fuel tank, vapor lines, and the EVAP canister for leaks. A leak can trigger the Check Engine light to turn on.
Filler Neck On The Fuel Tank
This is the part of the fuel tank where new fuel is sent into the fuel tank of your car.
In older cars, the filler neck has a valve to let in air without letting out vapor or fuel. Without a valve to let in air, the gas tank will collapse as the fuel pump suck fuel from the gas tank without anything replacing the volume of fuel that was taken out.
Most drivers overlook gas caps, but it is one of the most important components of the EVAP system.
Gas caps can be designed to have air vents to allow air into the tank as your engine consumes fuel. These gas caps serve as the air intake for the filler neck of the fuel tank.
The EVAP canister or the vapor storage canister is a plastic container that is close to the engine. It contains activated charcoal that traps fuel vapors. Some EVAP designs let air into the fuel tank through the EVAP canister.
A solenoid controls the movement of air into the canister. A problem with the solenoid will slow down the movement of fuel vapors from the fuel tank into the EVAP canister.
When there is too much vapor inside your fuel tank, the gas pump of a gas station will shut off prematurely. Gas pumps detect if there is too much fuel vapor in the fuel tank and interpret this as a sign that the fuel tank is full. This can cause you to take a longer time to fill up the tank of your GMC Yukon.
This problem can also be caused by another solenoid within the EVAP system.
The purge solenoid controls the purge valve that sends the fuel vapors inside the canister to the intake manifold. If this solenoid starts to fail (or when the purge valve starts to fail), the EVAP canister will be unable to empty its contents into the engine.
If the EVAP canister is always full, the fuel tank will always be filled with fuel vapor that will keep shutting down the gas pump when you try to fill your GMC Yukon at a gas station.
Problems like these can be solved by checking the solenoid, the EVAP canister, and the hoses that draw fuel vapor from your fuel tank and into the canister.
A professional mechanic can check and repair a problem with these components and fix them for you.
Why does the gas pump keep stopping when my tank isn’t full?
One of the reasons behind this problem is too much fuel vapor in the fuel tank, as we mentioned earlier.
To get gas into your tank while your car is still suffering this problem, look for a gas station that uses mechanical gas pumps. Mechanical gas pumps will keep pumping gas into your car as long as you’re pressing the lever to let gas into the fuel tank.
Another possible reason is that there is a problem with the gas pump. This is more common with mechanical gas pumps that can experience clogging as it gets older. Move to a gas station that is not using a mechanical gas pump if you’re having this problem with the gas pumps of a specific gas station.
Clogged Fuel Tank Vent
A clogged fuel tank vent will prevent air from getting out of your fuel tank as you fill it with gas. This will cause the gas pump to think that your fuel tank is already full.
Another symptom of a clogged fuel tank vent is poor performance.
A clogged fuel tank vent will also limit the flow of fuel into your engine. Fuel that leaves the fuel tank must be replaced by air, or there will be a build-up of pressure inside the fuel tank that will pull fuel back inside.
How do you unclog a gas tank vent?
A blockage in the gas tank vent is bad for your car, as we discussed in the previous section.
Unclogging the gas tank vent involves an air compressor to test the vent lines for clogging. If you do not have an air compressor (and you do not know which hoses and lines to test), then your only option is to bring your Yukon to a professional mechanic to fix the issue for you.
Additionally, testing for clogs in the gas tank vent involves disconnecting lines that can only be accessed under your car.
What are the risks of a blockage in the gas tank vent?
A blockage in the gas tank vent can be dangerous and should be fixed right away.
The blockage can create an excess build-up of pressure that can lead to fuel leaks. Leaking fuel that comes into contact with a source of ignition can cause fires and/or an explosion.
What does it mean when a car won’t start after getting gas?
This problem is often caused by a problem with the purge valve of the EVAP system.
When you fill your fuel tank with gas, the vapors coming from the fuel will suddenly get pushed into the EVAP canister.
If the purge valve that sends the fuel vapors into the intake manifold of your Yukon malfunctions and stays open, then there will be a lot more fuel vapors that will get into the intake manifold of the engine.
This will create an excess of fuel in the combustion chamber and will cause your car to become difficult to start.
It’s like the engine of your car is drowning in fuel when the purge valve stays open.
Bring your GMC Yukon to a professional mechanic to check the purge valve of the EVAP system. Another part that the mechanic will check is the solenoid that controls that valve. If the solenoid is starting to fail, then the purge valve can get stuck in the open position.
What are the symptoms of an EVAP leak?
One of the most common symptoms of an EVAP leak is the smell of fuel inside your car while you’re driving. Even a leak as small as a pinprick can cause a smell inside your car.
Another symptom is the Check Engine light turning on. This means that the EVAP system is detecting the leak and notifying you through the Check Engine light.
This light, plus the smell of fuel inside your car, means that you need to bring your Yukon to a professional mechanic to check the EVAP system for leaks.
Other symptoms that you might experience are hard starts, poor engine performance, and failing emissions testing.
A malfunction in one of the components of the EVAP system of your GMC Yukon can cause it not to take in fuel. However, problems with the gas pump or a clogged gas tank can also cause some issues.
Now you know more about these problems and how to address them.
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