Also known as the vapor or the charcoal canister, the EVAP canister has one important job: to keep vapors from the gas tanks from escaping into the atmosphere. It does that using one/two pounds of activated charcoal that’s very good at “trapping” fumes. Next, the engine’s intake system “pumps out” the vapors and sends them into the intake manifold. Alright, that’s it for the theory – now let’s move on to the practical side of things.
Like any other part of the powertrain, the EVAP canister doesn’t last forever. All those fumes can wear it out over time, dropping its efficiency. So, today, we’ll learn how to bypass it the fastest, easiest, and most cost-effective way, without even breaking a sweat. Ready to get your hands dirty? Let’s go right ahead and do it!
Signs of a Faulty EVAP Canister
Clogging, physical damage, and deterioration are the biggest enemies of the EVAP system. Plus, if you’ve been driving the same car for many years, chances are, the canister is low on charcoal, which means it’s not as effective as it used to be. Now, it’s important to say that a faulty EVAP canister isn’t at all dangerous. It won’t cause engine malfunction, make the ride less comfortable, or put you at risk on the road.
The most significant downside is the scent of gas fumes. On a hot summer day, the smell can get pretty strong. Plus, all those vapors pollute the atmosphere. And let’s not forget that in most countries, driving with a malfunctioning EVAP canister is enough to get a ticket. So, let’s take a quick look at the most common symptoms so that you know what to expect:
- The Check Engine light. This is arguably the most annoying symptom for any driver. The second the PCM detects a problem with the system, it activates the check engine light. A quick note: there are no specific codes for issues with the EVAP system; you’ll probably see a leak code or something like that.
- Trouble with the gas tank. When you add fresh gas into the tank, it pushes down on the fuel vapors that have been down there for quite some time. When the canister is working properly, it “accommodates” all those gases. However, if you have a clogged/damaged canister, the fumes have nowhere to go and make refills harder.
Yes, we all care about the atmosphere; however, according to statistics, most drivers consider bypassing the EVAP canister for two reasons. First of all, they do that to get rid of the nasty smell that can cause inconvenience. Secondly, a faulty canister is often the cause of a failed emissions test. In many US states, every single driver has to pass it to get approved by the DMV. Do keep in mind, though, that the lack of a canister can also be against the law.
So, now that we’ve got the basics out of the way, let’s talk about bypassing the canister. The best thing about this process – you won’t need any fancy equipment, tools, or expensive gear. I would still recommend putting on a decent pair of gloves, of course, but nothing more. As for the tools, a regular wrench and maybe a couple of extra hoses and caps just in case is all you’re going to need.
Bypassing the Vapor Canister
Alright, the first thing to do is to find the Purge Valve and disconnect it from the canister. You’ll see a couple of hoses: only unplug the lower one. The next step would be to “skip” the EVAP canister and connect the fuel tank’s vent line straight into the Purge Line. That’s not it yet: every vehicle has an air box. And, that box is “feeding into” the vapor canister. Again, disconnect the hose, but instead of plugging it into anything, just cap it.
That way, you won’t have to deal with any excess fumes while driving and run the risk of being stopped by a police officer. That is actually it! The last thing to detach from the canister is the pressure sensor (again, a very common part in all modern-day cars, bikes, and ATVs). Ok, now you can not only bypass but also unbolt the canister and remove it completely. Pick the right wrench, take out all four bolts, and take it off.
More good news: when you decide to put the canister back, that can be done in a couple of minutes. Since we didn’t cut any hoses or wires, we didn’t ruin anything. That means you won’t have to invest in new gear/equipment: just connect everything back exactly the way you disconnected it, and the canister will get back to work.
As I already mentioned, US drivers think about reinstalling the EVAP when they need to pass SMOG Control or DMV. Still, I would recommend keeping the canister on at all times, because it does, indeed, handle all the fumes pretty well. A quick note: if the canister is faulty, and you’re looking for a replacement, you can use this guide to remove the old canister and install a new one.
Bypassing the EVAP canister may sound like a lot of work, but, as we just learned, there’s nothing hard about it. All you’ll need to do is disconnect some hoses and remove the canister, freeing up room in the engine compartment. Keep in mind, however, that in many countries/states, it’s illegal to drive around without a complete EVAP system. So, you might want to reconsider.
Next, remember the most common signs of a faulty canister. That way, you’ll avoid expensive repairs, issues with the law, and get to enjoy your vehicle both on and off the road. And if you’ve got your own technique for bypassing the vapor canister that takes even less time and effort, I encourage you to share it with us all in the comments!