How the EVAP System Works
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- Опубліковано 16 жов 2024
- Here's how the evaporative emissions and fuel system work on your car.
The EVAP system is responsible for venting harmful gasoline vapours from the gas tank into the atmosphere, causing smog.
It consists of the gas tank, filler neck, cap, vacuum lines, switching valves and the charcoal canister.
When the tank is being refuelled, the fill check valve is opened to vent building fumes in the tank to the charcoal canister. The charcoal absorbs the vapour, and will release it into the engine through the purge valve so it can get burned.
When the tank is full, the fill check valve has a float that rises and cuts off the vent line through a diaphragm. This prevents liquid fuel from entering the charcoal canister.
The vacuum switching valve allows the ECU to pull and hold a vacuum on the evap system for self diagnostic. Using the vapour pressure sensor, it can determine if there are leaks and throw a check engine light.
These self diagnostics are part of every car with OBD2, and are essential for an emission test to pass.
The fuel tank is also cut open, exposing the baffles inside, as well as the high and low points of the tank and inlet check valve.
Vacuum lines in between the gas tank, charcoal canister and air filter ensure air is directed for proper venting, purging and self diagnostic.
Care must be taken when working on the fuel system, as gasoline vapours are extremely flammable.
This is what I call quality content, very thorough yet concise video and not boring unlike many others
+gacho thanks I'm glad you appreciate my work
speedkar99
And no horrible music.
Or in my case, great music that everyone complains about in the comments, because they are old.
You are the best at getting to the point. There are many channels that I wish would hire you! No silly intro graphics or music, just straight and to the point. Even if everything you said was a lie (I know enough about cars to know that's not true) you would still be one of my favorite youtubers. Excellent work once again.
I agree a large percentage of Canadians and North Americans fuck around with so much fluff, bs, stupid music that is louder than the presenters voice (a rookie mistake) and meaningless nonsense that it negates the reason why you would watch it. 😂 I don't want to listen to an obstacle course of jumps, rings of fire, and other superflous shit. Anyway - Thank you sir for this video although maybe not perfect it cuts straight to the chase with out the bs intro, plugs, links, ads, and idiotic crap. I know it's not an easy task to create videos and you've done a pretty good job at explaining EVAP SYSTEMS. 👏🏻 9:45
is amazing how much engineering goes behind every single part of a vehicle!!!
+viciousocean it sure is, I love learning something new every time I open something.
For sure. Given this, and the amount of knowledge required to be a good mechanic, it's amazing to me that mechanics don't make more money. I say this as a mechanic. Gone are the days of "grease monkeys" working on simple designs.
It's amazing how cars go 200k miles with only a few things failing
@@ben2687 A truly good mechanic that actually knows how to diagnose problems and understands cars very well is rare and most people would not be willing to pay $200/hr for an expert when they can take they're car to the next mechanic that will just start swapping parts for $100/hr.
What's more amazing is how much of it is absolutely unnecessary - like the entire evap system.
1:15 Searched for hours to find out what these hoses do and you explained it in 30 seconds. Man, I can't thank you enough.
+starguy9 I'm glad you learned something!
This was the best informative UA-cam video ever! No B.S. , just a fast, moderately in depth dive into the topic at hand with a real life tare down. Love it! Thank you , it answered my question and I learned a lot. Keep up the good work!
Glad you learned something new
Pictures and drawings are helpful...but...what you did is an excellent visual of the components and system! Thanks!
Your welcome, glad you learned something
The content is solid, the pace is quick (but not too quick), and there is no superfluous language or stumbling words filling the air.
This may be the greatest example of how an instructional video on UA-cam should be done. Well done, sir.
Thanks I'm glad you appreciate my videos!
2 12mm of rust. Lol.
+charls seal haha yea this car was rusty!!!
Very in-depth description with visuals. The cut-open visuals make this tech school-worthy. Nicely done, sir!
Mechanical Engineering 101 certificate for anyone who had completed watching the video.. Excellent descriptions of the functionalities and reverse engineering of the Evap system. Thank you!!!
You are welcome. Glad you appreciate my content
my old high school buddys are probably watching . we all struggled with cars for the last 40 years. after a while it was a right of passage. you've been busy in the garage after dark too , I bet.
Garage...eh...more like on the driveway...I've even filmed a few videos out in the dark too
"...held on by two 12mm pieces of rust". You made me spew my coffee. Well played!
Excellent through, concise, fast presentation... The best I have ever found
I someone walked into a vehicle evap autopsy . Amazing Job Explaining The inner workings. 👏
Lol. It's held on by these 6 points of rust. I love these videos
+Twist_the_wrist83 ugh this car was too Rusty. Darn winter salt on the roads
Thanks for showing the real thing in all your videos as supposed to just a diagram. It really makes it much easier to understand when you’re seeing the real parts come of an actual car!!
That's what I love seeing...the practical side of things by taking them apart
Damn, a bit complicated system just for catching vapor. Nice straight shooting video!
+Addictive_LiquoriCe your right. And it's self diagnostics is another nightmare to deal with when things get old and Rusty.
You explain so quickly that some people feel difficult to keep up with you
This helped me learn the basics of what an EVAP system is despite my crippling ADD. Thank you!
Glad you learned something new
the best tutorial, talking about evap system I have ever seen. This is educational.
Thanks I'm glad you found it helpful to learn
This is great!!! I hate bothering my brothers every time my check engine light comes on... stumbled upon your fine work while searching an evap system leak code. 😂😂 I love it!
Glad you enjoyed it
Sir you have the best visual and audio explanation of everything on UA-cam, thanks for sharing your videos with us 👍👍👍👍👍🙏
Always glad to see a new video from you. Top quality as always. You should do the ignition system and the trick where spark plug porcelain can break the glass on windows and windshields.
Thank you for the compliments, and yes Ignition system is on the list of things to film!
Thousands of people are equally frustrated by P0440 thru P0459 codes. They could eventually drive a person to rip it all out and cut it all open just like that. The narration was great. I would be saying stuff like "There is nothing wrong with you, why do you keep throwing codes?!?" Good video.
Thanks. You are right...those codes can get annoying but having a good understanding of the system definitely irons things out
You are the most understanding and easy to listen to Master of mechanics. Thank you
You are welcome
EXCEPTIONAL rundown clarifying a Toyota EVAP system. Great job!😀
Thanks 👍
I found your videos really helpful as I have a no start condition on my granddaughters Agila GM UK car. it seems Im not getting a signal to the evap solennoid I think because of your videos helping me. Thanks very very much. I really like how you chop these parts open so we can see how they actually function. Terific fantastic Ill be whatching all of yours videos
+colin Lyne I'm glad it helped and you've learned something!
Wow my boi ... u really spit that. Due to your clear and concise presentation I was able to absorb all this like a sponge.
Glad you learned something
I must've watched another video of yours when I experienced a previous car issue. I remember the toothbrush pointer!! Thanks for the education. Then and now.
That pointer tool is superb!
It works great
very good presentation, short, quick and easy to follow. Thanks.
my new favorite car channel... wish I would've found this channel back when I was in tech school , would've livened up my studies lol
+TheCoatneyadkins haha thanks. I'm glad you enjoyed it.
Excellent visual and explanation of the evap emissions and fuel systems. Thanks for going to the time and labor to explain to us.
You are welcome
Excellent explanation! Quick, concise and informative
Thanks
Thanks man! You made it really easy to understand the parts and hoses that otherwise seem like a mystery.
You are welcome. I was just as confused as you before I tore this down
Thank you. Trouble shooting and fixing my EVAP. This helped a TON!!!
Excellent video to decipher mystery of the EVAP system. Thank you for the great presentation. I only wish that the pace would have been a bit slower. I had to stop and replay the clip numerous times to properly understand the content; however your name explains it all.
The car guy I trust to explain how stuff works! Speedkar 💪
Awesome
Damn !!! Every word is a lesson. We should have more like you teaching at Colleges
This guy is so knowledgeable ... Much respect and if mechanics don't work out you could always be a comedian lol ... Tnx man
Thanks for the compliment. I prefer to stick with cars haha
Good morning u have done the best priticle class on evap system
This was awesome you answered all my questions without me even asking them.
Great video, well done! Straightforward and complete.
Great job!!!
Just wanna know If a faulty EVAP system could reduce gas mileage. I seem to have lost 60 miles on every tank refill since 2019. That amounts to much over a long period
I don't see how it could be directly related hmm
I know I have said this before, but you really should be a college instructor in automotive technology......you are great!
+John Oliger Thank you. I enjoy teaching what I love and am enthusiastic about.
This video is awesome. So what's causing high pressure to build up in the gas tank of my '01 Sequoia? Seems like it's either a clogged line or a failed valve or solenoid. The pressure was so high yesterday, even with the car off I could hear it venting somewhere when I stood near the fuel door, and I could see the shimmer of gas fumes. Had to let it sit with the cap off for an hour for the pressure to completely subside.
Somehow I missed this excellent summary. Question: With key off engine off as the engine sits overnight, is the canister vent valve open or closed? Does it stay closed "to a point", then opens to relieve pressure, if pressure is too high or too low?
Man I love seeing when someone masters their craft. Appreciate the vid Speddkar99!
Appreciate your feedback
The videos in this channel are always very very very interesting and helpful. The only thing that don't like is that you speak too fast, because i'm not native English speaker.
But after all, thank you for your time to make these fantastic videos and for sharing your knowledge with us
Thanks. I try to keep pace. You can adjust playback speed
@@speedkar99 Thanks man! I didn't even know that! Keep up the good work!
beautiful illustrations
Thanks
My Golf had a recall and needed all this stuff replaced, interesting video, very informative
Dude!!! GREAT vid explaining the evap system quickly and thoroughly. I have a question for you... my wife accidentally topped off my brand new Toyota 4Runner TRD Pro several weeks back (gas was spewing out of the inlet port when she finally stopped holding the trigger down). Today my check engine light came on along with ATRAC light and I get diagnostic codes P0441 and P0445 for the evap system. After my wife topped off... I looked up “what happens when you top off on gas” and found that the reason you don’t Top off is because you can damage your evap system. So, knowing this immediately after the top off incident I was expecting something like this might happen and so here we are now. My question is... what specifically might be damaged or need replacing in the system from a major top off? Which components should I zero in on? Could it be that I need a whole new canister??? Your thoughts on this would be MUCH APPRECIATED since I can tell you know what you’re talking about on these systems. By the way... it took some major effort and time for you to make this video and I can’t thank you enough for it. Really great work!
+Wolfgang51501986 the damage is likely liquid gasoline in the charcoal canister.
If you overfill until gasoline comes out of the filler hole and spills on the ground, to the level of the ventilation pipes of the fillerneck that goes to the evap canister will gasoline then come in or will it first go through the overfill check valve? In other words if you overfill it to much can you damage your EVAP canister? Always wondered how this system works.
The overfill valve is supposed to prevent that. Of it malfunctions then it'll damage your canister.
Good job on this video man, explained everything so well, helped me understand why I'm getting a p0457.
Glad it helped. EVAP is certainly something interesting to wrap your head around!!
Never heard about this system before thanks for your valuable information......
Your welcome
The funniest! Most engaging educational video, possibly, ever.
Thanks I'm glad you enjoyed it
That was an amazing explanation. You’re a great teacher.
Thanks!
One day I'll have my own school...
speedkar99 Start making a plan today.
Quality video, thanks for walking us through this
Glad you enjoyed it
Thank you for your excellent video! I am trying to troubleshoot the gas pump stopping after a few seconds when filling. 😓
You have a spider living up your EVAP drain tube
@@speedkar99 I wish it was that easy!
Have a '99 Camry 3.0 v6 (US Federal emissions). Owned for over 7 years, 1st check engine light today. Around 175K miles. Code P0441 (Incorrect Purge Detected) popped up today. Hottest day of the year if that makes a difference. Entire EVAP system is OE original and untouched. I'm somewhat familiar with EVAP function, but not exactly in detail for this exact model. I do not smell gas while its sitting in my sealed garage so I'm thinking there isn't any leakage from something like the gas fill pipe/metal vent lines.
Where shall I start? Gas cap? BTW I cleared the code to see if it stays away, removed and installed the gas cap to be sure it was tight, it takes some turning oomph to get it to click, so that part of it seems to function. I'd like to first check the purge solenoid, where's that at, on the charcoal canister, or in the engine bay? Thanks if anyone can help out.
You need to refer to the repair manual to get the solenoid locations and test them with 12V.
Use a smoke Machine to detect leaks.
This video really help me with hose routing on the charcoal canister. Thanks man! It's pretty much the same in the video except mine is a 1998 which has 1 less hose on the canister.
You are the best teacher.
Thanks
Thanks for the video. Highly informative and educational.
Glad you liked it. Thanks
I could watch this all day haha
Best way to learn
Yep that's the fundamentals of my channel
Scott Kilmer on his mechanic advice UA-cam videos warn us never to fill the gas tank to the rim because if there gas going inside the evap canister, it may ruin it. I have a Lexus and I had a Corrolla before and I am wondering with all your explanations if there is a built-in security valve preventing gas to go into the evap system?
Thanks for the answer.
All systems have an overflow prevention.
There's a check ball for liquid to not enter the canister.
Thank you for the answer.@@speedkar99
I'm amazed by the knowledge and (engineering in hard places) that our Mechanic treats as "everyday", "minor" problems to be overcome at ease!
Good Lad!
Great video but you are brave to do this without gloves great channel you have
Thank you for physically demonstrating the safety measureS one uses for such a detailed journey. You are no yahoo on utoob!
Now im about to rip open a big bag of chips ''to see what's inside"!
+Dale Bills haha and what did you find?
speedkar99 nothing much.. You know how they sell you air nowadays LOL.
Was it an O'Hare Air bag of chips? :p
@@dalebills9470 you can do a BBQ with those chips as well 😊😉 not kidding either try it I start my fire with chips in my chimney
one of the most informative video on evap system well done mate very impressed by your knowledge
+CrazyHHO19 thanks
Your right there isn't much out there on evap
I hope you did not have to assemble everything back together. Very nice job! Thank you
I have to pump my gas at 1 cent at a time. Would my charcoal canister be bad or fuel check valve be bad?
The canister vent is clogged
Great videos! Any suggestions on how I can learn more about cars and working on them besides UA-cam? Schools, courses, books, DVDs? Thnks
+John Mcadden do exactly what I did here....buy a scrap car and rip it to pieces. You learn best through experience, not just by watching.
You the funniest YT mechanic I've seen!
+Giovanni Foulmouth funny? Haha how so?
Well the first big laugh was when you used your brother's boxers to wipe that headlight and found a surprise inside and now in this video with the pieces of rust and whatnot. I watch ChrisFix, SMA, ETCG, Milan Mastracci, Schrodingers box and Oldskool funk and none of them are as funny as you.
You are a genius at your craft
My craft of using the angle grinder ?😃
Highly Skilled and knowledgeable on how mechanical and electrical systems work.
I mean you have helped me diagnose the problem brilliant sos didnt make myself very clear cheers Colin
Nice video. Seems like there are several safety valves in place, but do any of them prevent actual gas fluid from entering the canister in the event of 'topping off'? This is something I hear about, but not sure if it's true on new cars or some more than others...
Excellent car autopsy. Keep up the excellent work.
+Lane Burgess thanks, feel free to check my other videos where I cut other things apart
"...there are six pieces of rust...". A rusty 👍 and subscribed!
Seriously this car was a rust bucket.
And it kicked that bucket alright...
Nice demonstration
Thanks
Great video, thanks. Is there any way that if any of these parts were malfunctioning that the fuel gauge could read wrong?
No. See my fuel pump video for how the float works
Cheers, will do
Amazing how complicated these systems are, just to mitigate all the problems of internal combustion cars. I am so glad that all of this is a thing of the past as electric cars are taking over.
electric cars are great for certain lifestyles, but not all lifestyles are compatible with something that needs to be charged every night, electric cars are really no better for the environment anyway, although I would love to own one someday. You’re right these evap systems are bullshit, but engines will always be a passion & hobby regardless of how great electric cars get, nothin wrong with liking both though!
Did you actually barbecue the charcoal?
+thekillersnake94 it would make my BBQ chicken smell Like gasoline
@@speedkar99 So, yes then
What’s the difference of splashing on a little gasoline on briquettes? It burns always once the coals get white and ashen.
Thanks for taking the time to rip stuff up!
Your welcome
I love your video so much! This is exactly what I was looking for.
Awesome!!
excellent video. which area in this EVAP causes p0440 code ?
When there's a leak
Great video. You sound like a fellow mechanical engineer
EXCELLENT VIDEO! Thank you not only for going to the trouble to take the system apart and explain it component by component, but also for taking the time to so thoroughly understand it yourself. If I might point out one possible correction, I believe at 1:01 you swapped the identification of the purge line from the canister and air inlet line to the canister. The purge line, if I'm not mistaken, is the one with the green cap on the test port.
Thanks
It was quite the system to learn and decipher
Maaaaaan, THANK YOU! Saved me a lot of trouble. Great teacher and funny too. Cheers!
I'm glad it saved you and you were entertained 🤣
Thank you for the very informative quality video.
You are welcome
This Man is like a Mexican Chris fix. I fcks with it
I'm not Mexican I'm Canadian
Howdy. I have a 1998 3.3L Nissan Pathfinder. 175,000 miles. Great condition. Stock. My tank gets alarmingly pressurized when driven a couple hundred miles. I don't have any codes. My Nissan gas cap visually inspects clean and good. Does not leak.
I even disconnected all hoses on the EVAP system and cracked the gas cap. No codes were made either. How can that be? I drove it dozens of miles to test. To see if the missing stopped or codes would appear. No codes, except random misfire. Every now and then, but the motor is obviously missing mildly to badly all the time. It gets worse for a while when I refuel. For a few dozen miles.
When this system started doing this, I started getting a random misfire code at the same time. These may be unrelated. Not sure.
I have verified purge valve works, hoses are clear now. One was dirty about 2" clogged at the canister for the purge line. It looked like charcoal dust. All other hoses clear.
Any ideas? I was going to remove the plug from the cannister ambient vent valve and see what that did. It should toss a code right? And make the valve open, from my understanding? I don't want the tank to pressurize like that again. It will spew and hiss for about 6 minutes when cap is removed. I've never seen a vehicle do it this badly before.
Thanks!
You are really good at it very interesting watching your videos keep it up bud.
The charcoal buid up during the engine is on?? Or the canister contains charcoal to absorb the gasses??
Everytime you say "pieces of rust" I lose it lol yet another job well done
This was one rust bucket
Thanks you for all your awesome explanation you are the best sir
Your welcome
If there is a evap leak with code p0440, toyota avalon 2000, do you think the overfill check valve is the one causing the leak? Thank you.
No
I'm about to replace the vacuum switching valve..while mine is not quite as rusty as yours I'm wondering how hard it is to replace while on the cannister. Is it clipped on or bolted? It's on a 04 4wd matrix xr so much easier to get to while on jack stands.
I like very good explenetion thank s
I love how u do videos!!
Very informative. Thorough. And funny!!
Verry susinct!
Is the evap canister vented to the atmosphere only to draw in fresh air when reburning the vapors in the engine?
No it's vented to rid of potentially explosive fumes
speedkar99 Do you mean in case there are too many vapors that can’t be held inside the canister?