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GMC Sierra 3500 Gas Cap Replacement Costs
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What is a Gas Cap?
Are you from one of those places where they don’t let you pump your own gas? If not, then you should know what a gas cap is. You know what? Even if you are, you should know what a gas cap is. It’s pretty straightforward and simple.
The gas cap is the cap for your car’s fuel tank. It’s what you unscrew when it’s time to put gas in your car, and what you put back on when you’re done fueling up. Pretty simple, yeah?
You might think that a gas cap simply serves the purpose of putting a lid on the fuel tank, so that the gas doesn’t spill out as you drive. And that’s certainly a big part of it. But it’s not the only part of it.
Gas caps serve a bigger purpose than that. They trap in fuel vapors that would otherwise leak out of the system. This allows the car to use the vapors, increasing performance and fuel mileage. And it keeps the vapors from leaking into the atmosphere, which is a vital part of the car’s emissions system (and the reason your car can hopefully pass an emissions test).
The cap also keeps harmful elements from entering the car’s gas tank. From bigger items like leaves, sticks, and pebbles, to smaller debris like dust and dirt, the cap is a barrier that protects the fuel tank, and keeps the gas as clean and pure as possible.
So, yeah. That little plastic device that you never really think of is actually quite important, even if it’s simple. But it can wear out over time. The more you unscrew and screw it back in, the more you wear out the seal. Even a tiny imperfection in the cap can allow vapors to escape. Or you can easily damage it by, you know, dropping it, or damaging that part of your car. Or, if it doesn’t have a leash on it, perhaps you’ve simply forgotten to put it back on, and drove away. No judgement (okay, maybe a little judgement).
Symptoms of a failing Gas Cap
Check engine warning light comes on
Hey look, it’s your favorite indicator light.
Yeah, I get it. Your car is driving fine, so why do you need to listen to that tiny little light, right?
Well, because you might be able to stop a little problem, like a malfunctioning gas cap, before it turns into a bigger problem. If your gas cap isn’t creating a complete seal, it will allow fuel vapors to exit the system. This will be detected by the evaporative emission control system, which will notice that something is funky. And just like that, your check engine warning light will come on.
Gas cap warning light
Oh great, another warning light! Many modern cars have a gas cap warning light, to let you know when the gas cap isn’t on. Usually this is because you simply forgot to put the cap back on.
But sometimes it’s because the cap is on, but not forming a good seal. This can be due to the threading wearing down, or just damage on the gas cap. But if the light is on, even though you’ve put the gas cap back on, you probably have a faulty cap.
Gas cap doesn’t screw on
You also might notice that the gas cap isn’t screwing on correctly. Maybe it never clicks into place, or maybe you can just feel the cap being loose, or not holding. Either way, that’s not good, and that will allow vapors to escape the fuel tank, and debris to enter it.
Car cabin smells of raw gasoline
There's a place and time for everything. And the gas station is the place and time for the smell of gas. Not when you're out driving your car. If you notice that you smell raw fuel while you’re in your car, it could be due to an issue with the gas cap.
How urgent is a Gas Cap replacement?
You can safely drive your car with a broken gas cap. But if you don’t address the issue, it will cause engine performance issues, poor fuel mileage, and cause your car to fail an emissions test. So, maybe just get it replaced.