How the EVAP System and Gas Tank Work

Here's how the Evaporative emissions system work on a modern automobile.
The purpose of the EVAP system is to control the release of gasoline vapors entering the atmosphere, causing smog. It is a self-governing, mandated system that vents most harmful vapors into an external charcoal canister for refinement.
The system consists of several components: The gasoline tank, the fuel sending unit, temperature sensor, pressure sensor, vent and purge solenoids, charcoal canister, vacuum hoses, filler neck, gas cap and fuel check valve inside the tank.
When gasoline is being filled into a tank, vapors are routed to the charcoal canister for refinement. Air and water vapor are allowed to vent to atmosphere, allowing the tank to fill up seamlessly without trapping air.
During normal vehicle operation, gasoline vapors are routed to the charcoal canister and then sent to the air intake through a vacuum hose. The engine then reburns this vapor, with the ECU compensating accordingly for a richer mixture. The release is controlled by the purge valve.
A pressure sensor situated on the purge line (near the charcoal canister) allows for self regulation of the EVAP system through OBD2 protocols. During certain drive cycles, the ECU can detect if there is any leaks in the EVAP system and throw a check engine light accordingly.
It does this by drawing a vacuum on the system from the air intake, then sensing if there is any pressure drops (and the extent of the drop) due to a leaking system.
In this video, the entire EVAP system is gutted from an Infiniti G35, cut open, cross-examined and explained. The gas tank is cut open to examine the vapour cut off and liquid recovery floats, the dual-tank like system (due to RWD configuration) and the valving inside the filler neck.
Furthermore, the EVAP canister and vent valve is cut open to examine its role in the system.
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[@speedkar99]

To see how much more complicated a Toyota EVAP system is, check out my other video here: kzbin.info/www/bejne/nWXPeauJdt6Zba8

[@alexeimakes]

thanks so much for this video! will check out the toyota one after

[@speedkar1005]

You are welcome! The Toyota Corolla has a lot more valves with diaphragms and an extra vent line from the engine, yet was a generation older than this Infiniti. It was ahead of it's time for an economy car.

[@speedkar99]

You are welcome!!

[@speedkar99]

The Toyota EVAP system is so much more complex with it's valving and vacuum lines and it's older than this Infiniti

[@fun_ghoul]

@@speedkar99 I wonder which is more effective at not venting fuel vapour...

[@MichaelAChang]

3 classroom lessons wrapped up in under 14 minutes - nice job.

[@speedkar99]

Pretty much my style....short to the point and dense with info

[@Graham_Langley]

Couldn't have put it better.

[@Flightstar]

Ya I like this style. Most info videos are just too long winded with too much bs words

[@nokidding152]

@@speedkar99 you are greatly appreciated, sir. When you show up in my search results, it’s an automatic click. Thank you.

[@johnfearn4979]

Every time I watch your videos I learn something new. I never knew a fuel system was so complicated. Thanks for explaining it all so well.

[@speedkar99]

You are welcome. I'm glad you learned something from my video!

[@hestheMaster]

Your explanation of how a fuel system works and showing cut outs is excellent. Safety first in cutting open a fuel tank, which most people never get to see is super cool!

[@fernandoanatomia]

Always wanted to understand how this system works. This channel is a gold mine. Thank you for sharing such great content!

[@speedkar99]

You are welcome! Stay tuned for more

[@Emils2006]

I always think, I know everything, and then I watch your video and understand that I don't know anything

[@speedkar99]

Uh so does that mean you didn't understand my video ? 🤔

[@Emils2006]

@@speedkar99 I meant , I didnt knew a half of things you showed.

[@bassam_salim]

I heared that the smart person is the person who know that he does not know everything, and the stupid one is the one who thinks he know it all.

[@chrisbrowning360]

The most concise, effecient, and informative thing I've seen in my life. Amazing video, thanks for uploading!

[@LoganTanner]

This video was amazing. Huge props. I noticed super high pressure in the gas tank of my 2001 Toyota Sequoia yesterday after a drive in the mountains. My research points to the EVAP system, so thumbs up for this incredibly detailed and hands on video explaining the whole thing and where and why faults happen. Off to watch you video on the Toyota EVAP system now.

[@tankeryanker7028]

As a trucker, I roll into different job sites with different jobs and always running into new and unfamiliar jobs. I always tell the clients to explain it like I’m a 2 year old lol. You truly have a gift

[@speedkar99]

Awesome thanks

[@SerandibBroadcast]

I got to know this channel very recently. Have to say sir, this is very informative and educational for everyone. I drive my car daily without knowing any of this. You are not just uploading some video content, rather teaching thousands like myself. Thanks and keep up the good work.

[@speedkar99]

I'm glad you appreciate my work, and can learn something!

[@jamesvisocky1529]

Thorough, articulate and well explained. I especially like seeing the parts cut open and cross-referenced with diagrams. This answered my question about what the canister is for plus how the whole evap system works, since the canister isolated from everything else would not make a lot of sense. Great job!

[@bobbykeyz1263]

So I had a tighten gas cap on my Tahoe. I changed the gas cap and reset my check engine light. A few days later, it said it again, and my check engine light came back on. I needed to learn more about this evap system. I have to say you explained it better than any other KZbin channel. Thank you. You just got another subscriber.

[@mattmcgyver135]

This just saved me a huge mess of diagnosis on my G35. I could not find out anywhere how this worked let alone what it looked like. You are straight up my hero, thank you so much.

[@Turulcky100]

Why is a tooth brush explaining engineering to me?

[@speedkar99]

Teach-brush

[@fun_ghoul]

I mean, it's better than a fuel tank explaining oral hygiene, amirite?

[@bryankirk3567]

Because when it's dirty, you should have learned something you didn't know before!

[@ferntaylor5347]

😂😂😂😂😂😂😂😂😂😂😂

[@galaxytraveler5779]

LOL

[@timothyalan34]

Amazing attention to detail, incredible explanation, and very thorough. Not only am I impressed with the depth of your knowledge, I'm in awe at how interesting the inner mechanics of a vehicle are. Great video, one that I'll revisit to reinforce the information presented. Thank you for potentially saving me a lot of money.

[@speedkar99]

Thanks. I try to do some research before diving in but ultimately I'm learning as you do when I take these parts apart!

[@StativeCreative]

Very clear explanation! To the point with real world visual aid and diagrams to help specify where no visuals are available. Instant subscriber! Thank you!

[@ytugtbk]

Outstanding video. Loved the fact you not only used diagrams but actually tore and cut everything apart. Well done! Who'da thunk so much engineering goes into capturing and recycling gasoline vapors.

[@joshhayes3433]

I'm pretty sure you've just coined the term "an incision with an angle grinder" :) I've always wondered about the evap system, great explanation, thanks!

[@speedkar1005]

You are welcome!

[@speedkar99]

Pretty much! Glad you liked it

[@pbierre]

This is a good tutorial on the pre-2006 OBVR design. The next generation design, EVR Phase 2, adds a Refueling Vent Pipe directly returning vapor from the tank to the filler throat during fueling. The EVR Phase 2 gas-pump-nozzle adds a return path for fumes, suctioned into a small orifice (3mm) on the nozzle. In EVR Phase 2 vehicles during refueling venting DOES NOT depend on the path through the CC (as it does in older OBVR cars).

[@whereisbenzo]

So does that mean I can rule out anything CC related being the reason for why my 2019 M240 cuts off during refueling? I disconnected the line going from the tank to the CC as to troubleshoot if it was that but the pump still clicks off. At this point I’m wondering if it’s the valve at the bottom of the filler neck or the vent valve in the tank that vents to the pipe that leads to the CC.

[@Graham_Langley]

A brilliant video. I knew what the evap system does but a teardown like this fills in so many gaps.

[@speedkar99]

Thanks

[@davidellett2620]

Excellent! This is the way videos should be done. Diagrams, parts cut open, detailed explanations without wasting even a second of time. So much so that I had to repeat a couple parts that I did not understand. But that's perfectly okay, I don't want other peoples time wasted while having to wait for me and vice-versa. Perfect!

[@speedkar99]

Thanks! That's my style

[@ibrahimeltony4865]

Excellent 👍 One cannot explain more the fuel EVAP system like this.

[@speedkar99]

Thanks!

[@LAnonHubbard]

This is a really good video and got me a long way to understanding the EVAP system. Will need to watch again a couple of more times to "hoover up" more of the details.

[@speedkar99]

Glad you took something away from this 😊

[@Qharisma]

This is the best visual explanation of the EVAP system I've found. God bless you.

[@alm7707]

very good description of how the system works. I have cleaned many canister control valves because they were full of dust. (several table spoons full from most of them) I've seen the vent hose full of tiny pebbles too. This is common when you drive on gravel roads.

[@scootergem]

i've never seen a video where so much effort was put into it. bravo. to call this a good job is an understatement. thank you for taking the time and for sacrificing that poor gas tank and canister for the enlightenment of your viewers. i'm now a subscriber and i can't wait to see more!

[@speedkar99]

I got a whole channel of videos like this, hopefully you can learn and share!

[@rickt2419]

Another great and detailed video, very educational! Thank You! I am going to share this video on my Toyota Nation Forum friends...

[@speedkar1005]

You are welcome! Sure please share on TN, I was thinking to make a post there too, but send the link when you have it

[@speedkar99]

You are welcome. I was going to make a post there as well

[@c79891]

One of the BEST & MOST COMPREHENSIVE, detailed analysis I have ever seen. This guy is excellent. Bravo for sharing your knowledge with the rest of us dummies.

[@johmu5466]

This is one of the BEST explanations of EVAP system components ever....! Thanks...! This understanding makes a huge differenece when troubleshooting EVAP issues.... Great video... Well done...!

[@solarflare1008]

You should be in a Mechanic Institute teaching how to do things the proper way. Great video.

[@speedkar99]

I should open my own school online

[@SketchbookGuitar]

@@speedkar99 If you teach using a used toothbrush there I'm in

[@fun_ghoul]

@@speedkar99 KarAcademy dot com? :-)

[@frankderryberry1412]

No no no....each error code...404 or 4040...I forget... is worth $ 800 to them.

[@dominicfong6341]

Thank you very much for cracking the mystery in the little black box sir!

[@speedkar99]

You are welcome....you are right, it's one of theore overlooked systems in a car.

[@samuelberry9152]

no better way to learn about a system than this actual, tear-down of it!!!! Thank you for your superb content!

[@bryansmith4856]

This video is AWESOME - the amount of time and work it has saved me to learn all this information is SUPER helpful! Thank you!

[@juanpoggio4599]

Great video! I learned a lot in 13 mins, had to pause it quite a few times to be able to retain all the information before moving forward. I love that you took everything apart to explain how it works. I usually take things apart, but wouldn't have been able to take apart an entire fuel system. Now I can troubleshoot problems with the fuel system!

[@Jimmy-vi3zv]

what do you call two mexicans fighting??? answer: Juan on Juan

[@andycsurka9235]

Incredible video. 100% thorough. This is by far the best explanatory video I've ever seen. From a mechanic to a mechanic - keep up the good work

[@AhmedHadjSaid]

I just found a real mechanic teacher, an expert. Appreciate your explanation bro, very happy that i get the chance to see your detailed presentation. Thanks a lot 🙏 I like your toothbrush 😁

[@jasongennero2080]

I love this channel he explains everything perfectly with diagrams and visuals by chopping the components into pieces to actually look inside of them. I haven’t come across any other automotive channel that actually dismembers the parts and components of a vehicle to better explain them. The only reason this guy isn’t rich yet due to doing this technique that no other channel does is cuz nothing many ppl know of this channel. With more exposure this guy would be rich and have way more subscribers. As a mechanic myself this channel has been invaluable to me due to him cutting open parts for me to take a look inside and I feel that so many more mechanics would love this channel also due to this. Thanks bro, keep up the good work.

[@manickn6819]

I enjoyed this video. While I do disassemble car parts I doubt I would have ever gotten my hands on an entire fuel tank and associated systems.

[@speedkar99]

That's why I bought an entire car to take everything apart....easiest way to obtain.

[@zacharyparis]

i suddenly feel like i need to brush my teeth.

[@speedkar99]

Well I guess you learned a little more than just the EVAP system

[@Paula20165]

I know this video it's been there for a while, but thank you for taking the time to explain the system.

[@j168vlogs]

Gas pump malfunctioned today and overflowed gas tank. Read a bunch of forums saying over fueling may cause damage to the charcoal canister, made no sense that a there wasn’t any fail safes but now I see there is one. Awesome thanks for the video. Btw the shoes freaked me out for some reason lol

[@superduty4556]

You sure know a lot about cars for a dentist.

[@speedkar99]

Plot twist: I'm actually an Engineer

[@alexeat-sand9938]

Try to ignite the charcoal to see if it catches on fire quickly

[@speedkar99]

Hey that's a good idea. Was also thinking to use the gas tank as a fire pit...but it's edges are so sharp.

[@Veik_Reikis]

@@speedkar99 I know I'd watch that charcoal getting lit up. Super saturated from years of gas exposure? Sounds like the ultimate BBQ lighter.

[@no1555llo]

I really thought about it when I saw charcoal 😂😂🔥

[@Graham_Langley]

@@Veik_Reikis The charcoal absorbs the vapour then releases it when the engine's running.

[@JoeJ94611]

@@@speedkar99 I would ignite just a tablespoon first.An acquaintance lit some charcoal that had gotten contaminated by a chemical while in storage in his garage and it exploded.His face was burnt pretty badly.

[@PARKWOODECHO]

Great video! Nice to see you take everything apart and actually see everything.

[@candidomiguel5054]

Great. One of the best explanatory videos I've ever seen in my whole life.

[@battutulu3030]

World first ever talking "Tooth brush"

[@VKSgtSLaughter]

MERCH idea... t-shirts with a toothbrush on them, a toothbrush classroom pointer, and maybe a plushie toothbrush. LOL!

[@voidisyinyangvoidisyinyang885]

follow the bouncing dirty toothbrush....do sing alongs also?

[@TuanNguyen-fo2pf]

Great informations, thanks you for showing the cut out.

[@speedkar99]

You are welcome. Lots more to come in this series ...tell me what you'd like to see!

[@stratztn1]

Better than any lesson I've had in school for real !

[@bsclifton]

Great job with the video! A lot of material to digest, but it's easy to watch a few times when you miss something. I couldn't help but laugh at the different beat up old tooth brushes LOL! Those make great pointers and it's priceless when you "drop the mic" by throwing the toothbrush onto the big pile of evaporative parts at the end 😂

[@abdulazizal-zadjali8574]

Thank you bro... great video well explained in detail with all components of evap system❤️

[@speedkar99]

You are welcome!

[@haukenhung]

Another amazing video Sally!

[@speedkar99]

thanks! Your still up and about 😏

[@jessicaaugust8794]

This is the best most informative video I've ever had the pleasure of watching...I've replaced my entire fuel line/pump system... now working on the EVAP system, this was a great video on what every thing is and does...!!! 🥰

[@jimmytowns2471]

This is the best video I've seen explaining the EVAP system used on our vehicles. Thank you! I recommend changing your tooth bush though. Looks a little worn.

[@escueme]

Amazing stuff bro

[@saadghand3726]

We need a diesel engine video please thank you for your efforts much respect from Morocco

[@speedkar99]

Wow so far away! Thanks

[@geoben1810]

Clear, concise, professional exploration of a technical subject so that it's more easily understood. 👍😉

[@Toguro-oy3ld]

Very informative. I like how you cut open the gas tank and then went right to the toothbrush as a pointer again

[@fun_ghoul]

Seems like there was still a fair bit of vapour space when you drew the "scalpel". I wonder if you could use something like CO2 cartridges (or nitrogen, if you have) to push out any potentially remaining fuel vapours...

[@arthurfricchione8119]

Excellant video speedkar99. Will view the others. Thanks much 👍

[@speedkar99]

You are welcome!

[@micjag6069]

Excellent video. Great detailed explanations of how the whole system works and what actually happens, not just codes

[@mauipaul]

So much information packed in a short video and explained clearly. Thanks!

[@rodolfocruz5161]

I didnt know what a EVAP was, now I know what the EVAP is.

[@speedkar99]

Awesome!

[@PBWillyWonka]

thanks for your videos, very informative..!! im subbed!

[@speedkar99]

Glad you subscribed thanks

[@nikolaijakov5411]

the kind of teacher that I always wanted to teach me... Thank you very much for the videos.

[@ben3mar]

Thank you so much, a clear, simple and straightforward explanation, I love your style, keep it up and please accept my appreciation and gratitude.

[@speedkar99]

Thanks for the compliment

[@fun_ghoul]

_"Safety first!"_ >hooks live battery terminals up right beside vapour-spewing jerry can

[@speedkar99]

Very safe

[@siachen6680]

I hope your brother has a good dental coverage since his tooth brushes keep disappearing😂😂😂😂😂

[@patrickwright9371]

I'm sure he returns his brothers tooth brush after he makes each video.

[@Farseer1995]

Wow, dude, this was incredibly informative! A whole comprehensive overview of the fuel system. I've learned a lot thanks to your clear explanation, thanks!

[@gr423]

I'm never going to look at my toothbrush the same way again, so much wisdom. Thanks for the video, great job.

[@Gabriel2.0]

6:44 random leg appears randomly

[@speedkar99]

The wife telling me it's time for dinner

[@DarkLinkAD]

Flexibility ;)

[@ciscolypse]

yeap, i was llike wtf

[@01001011011010010110]

When would the system vent the vapours into the intake and when would it vent them into the atmosphere ? Why not only vent to atmosphere or only vent into the intake?

[@speedkar1005]

Venting to atmosphere is needed when refueling (engine not on) or if there's too much pressure in the tank and it needs to release. Otherwise, the ECU determines the correct timing when driving to dump the rest of the vapors into the engine to be reburned.

[@speedkar99]

It would vent to atmosphere when refueling (engine off) or if pressure builds too high. The ecu determines when driving to purge the canister to the intake.

[@fun_ghoul]

If I may be so bold as to rephrase da man, the car decides based on sensor inputs if venting needs to occur at all, and if so, whether the motor can use the fuel at that time. If not, the vapour is vented to the ozone layer. Damn.

[@padraiggalvin2807]

@@speedkar99 I have a nissan RPS13 with sr20 engine 1996. emissions go quite rich at idle only. The evap was removed before i got the car. could it be possible that the evap solenoid should vent fumes on idle. Then this unmetered air/fumes would reduce emissions. Any info appriciated . thanks

[@vtecnerd]

Very, very informational video, thanks for taking the time to make this! Needed to understand what the hell an EVAP system is and now I do!

[@Enigmaafk]

Some really high engineering on the system that we take for granted. Nice video break down.👍🏼 I have to go diagnose a check gas cap error now.

[@7thfloorisnomoreq790]

Don't all mechanics carry a dirty toothbrush around with them? I sure do

[@speedkar99]

The most useful tool after the 10mm socket right?

[@fun_ghoul]

@@speedkar99 The 10mm and dirty underwear are the two most common in the junkyard, that's for sure.

[@frankderryberry1412]

@@fun_ghoul I got both in my garage.

[@fun_ghoul]

@@frankderryberry1412 Is "garage" a euphemism? ;-)

[@frankderryberry1412]

@@fun_ghoul No I'm not Catholic.

[@mustafaYkhan]

Good show 👍👍

[@speedkar1005]

Awesome!

[@speedkar99]

Awesome thanks

[@4DZC]

Awesome video. Thank you for taking the time to explain all of this in detail.

[@darrenhaverlock7025]

Best mechanic videos on YT I learn something everytime from your videos 👍

[@Atetus94]

Why some cars after opening tank cup loudly sucks air?

[@speedkar99]

Because the EVAP system draws a vacuum on the system to test it

[@mdbeckykhan]

Great video👏 Btw how many toothbrush do you have! 😜

[@speedkar99]

I just keep stealing them as I use them. It's not like they need them that much anyway

[@jonivanart]

Great video!! Thanks for the explanation and refresher course. I'm currently trying to adapt an Evap into a project and haven't worked on these systems for 25 years. I'm a new subscriber now. 👍

[@speedkar99]

Thanks

[@jamesmartin7402]

Great Info! As a person who was a mechanic full time, This is excellent training.

[@speedkar99]

Better than school

[@9HighFlyer9]

Nice video on a neglected topic.

[@speedkar99]

You are right, not alot of people pay attention to the evap system until it's time for an emissions test

[@9HighFlyer9]

@@speedkar99 I recently purchased a cheap smoke machine mostly for finding vacuum leaks. I decided to check out the evap for leaks on a project truck of mine. It looked like the back end was on fire from the hose missing clamps on both ends. Never set a code but it also doesn't get driven much.

[@fun_ghoul]

The charcoal is still good! You can use it in your Brita...

[@speedkar99]

I still have it if you want it...haha

[@janantoni3604]

Dude you are like me when I was 5 playing with the toys disassembling., cutting. etc. Only you are making more sense explaining how things work.Exelent teacher.

[@charlesharrell8798]

i just watched and it felt like I was in school, I loved it sir, very detailed.

[@jhsevs]

Do Diesel engines have evap systems?

[@speedkar99]

Diesels don't require it because it doesn't evaporate nearly as quickly as gasoline

[@tiukawni]

HELLO VERY NICE EXPLAINED BRO FYI NO HARM WAS DONE TO SPEEDCAR99 BROTHER IN THIS VIDEO HAHAHAHAHAHAHHAHAAHHA

[@speedkar1005]

Yep my brother was safe for this one...

[@speedkar1005]

Actually....I poured this gas (87 regular) into his car which takes premium....shh

[@speedkar99]

Actually I poured 3L of regular gas into his Acura which takes premium...shh don't tell him

[@tiukawni]

@@speedkar99 for me i put some diesel in it hahahahaha

[@earldaisgomez3959]

Dear sir. Greetings. Sir. You're not only a EVAP System doctor but also a Experienced Surgeon.

[@speedkar99]

Yep, my angle grinder is my second hand haha

[@kristianhermann5971]

Awesome vid, I love learning about how my car works. The cumulative engineering know-how in a modern car is staggering.

[@speedkar99]

I'm amazed myself at the complexity of how everything works together

[@awongutume]

And the tooth brush?

[@stoned12345678910]

7:00 another entity o_o

[@rychupaprok7251]

Brother's shoe :)

[@speedkar1005]

My wife's shoe

[@speedkar99]

Wife's shoe

[@jms8063]

Very insightful, clear and concise. Thank you!

[@siachen6680]

I just subscribed sir. You deserve it. So much in depth detail of how different system in car work. Theoritical and practical demonstration. Love it.

[@speedkar99]

I'm glad you appreciate my work

[@chefsafi981]

Hiiii

[@speedkar1005]

Hello

[@speedkar99]

Hi

[@pmag3200]

I guess you're not going to put it back together😁🤣🤣

[@speedkar99]

No way

[@pmag3200]

@@speedkar99 by the way great video and good detail and explanation

[@andrewlaporte9598]

Love this video, pair this up with how a fuel pump dispenser works and how it shuts off automatically when fuel reaches the top of the filler neck.

[@speedkar99]

Yes that's vital to stop overfilling

[@thefish8002]

Excellent video! I'm going to send this to my father to help him fix the system on his Honda Accord.

[@speedkar99]

Hope it helps

[@cifamotanii4587]

I know, you just love to brush your teeth! 😬😀👍

[@speedkar99]

Encouraging good hygiene

[@fluddfamily7861]

Wow what a detailed explanation of the Evap System 👍🏽

[@qrs3658]

Very good instructional video. This is way much cooler and descriptive than going to college to learn these things. Keep providing videos like these. Its very educational. I hope some Automotive School will use you video for teaching lessons.