6Speed's Lectures: How your EVAP system works 

The simplest and best EVAP tutorial I've seen so far. After watching and listening to this video I thought it worthwhile to subscribe to your channel. Keep instructing the way you instructed this video. 👍

Omg this is so helpful and I’m only 1 minute into the video. Love the power point structured presentation! Thank you for this !

Thanks for the clear and concise video. Doing diagnostic on one now and wanted to make sure I was clear on theory of operation. This was the best one I found.

Thank you so much for this video. I have two cars with codes indicating EVAP system problems and you've helped me understand how the system works before I begin fixing it.

Thank you for this mate, very well put together.Watched this before going into work to solve an EVAP PROBLEM!

Very clear presentation. No higher compliment to be given on U-tube.

I know this video is a couple years old but awesome job. Something new I've recently seen on a Chevy Cruze with the 1.4 turbo was a bad one way check valve in the purge valve assembly. It was letting unmetered air into the engine and causing a lean condition. Again, great job with the video, just wanted to share a little more insight into some possible failures.

Thank you so much for this video. Your explanation is extremely easy to understand and really good.

As a technician, I salute you on a clear and precise presentation. Job well done !

Quite an informed video on the evap system and very well presented.

Excellent video to provide a basic understanding of a car's evap system. Thanks very much.

Thanks for the explanation a and training Im a life long learner and I'm happy to learn from you and I will keep on learning life makes me want to learn even more .

Thank you very much for this! you explained this very easy to understand. Keep up the good work. I'm subbing now.

The best video I have watched on this subject. Keep it up Thanks

I have been searching all day and finally found this content that explained the NVLD . I was mislead by other videos showing more common EVAP systems.

Excellent video. Extremely helpful information and diagrams are excellent tools for understanding.

Great video. Very concise and well explained.

I didn't expect to see thermodynamics material, that was a pleasant surprise!

It finally makes sense - well done teacher!

Very helpful video, simple explanation with diagrams are the best, thanks so much,subscribed 😊👍

I found this video informative, and I learned something.

Very informative. Thank you for your work.

That was a great video. Thanks.

Very good lecture. Learned a lot, thxs

Great info man! Thanks for sharing! I had my 1st ever EVAP code P1450 on my Ford Windstar a couple weeks ago and it turns out the line leaving the purge valve to the intake was so dry that it by itself would no longer hold vacuum.

You are the best... Thanks

EXCELLENT EXPLANATIONS.

VERY Excellent video!

very clear explanation.

Great content, thanks for this video.

Good video. Good explanation. Just replaced the purge valve on my 2010 Ford Fusion. It was stuck open mechanically. Apparently this is rather common on the Ford purge valves. Ford had a good valve for years ,then did a redesign...... then not so good.Curious if they did another redesign to fix their initial redesign.

Great, great, great video, thank you very much, very helpfull.

thank you man!!!!! very nice video!!!

excellent video! thanks

Great video I found it very interesting seeing the various systems that she's diagrammed I'm having an issue with a 2000 Ford Taurus. The EVAP test never completes and I think there is an electrical issue with the vent solenoid on my car's system and provide a constant positive 12 volts and when it wants to close the vent solenoid it uses a transistor to pull the negative lead to ground. Now I've tried just connecting the solenoid to an accessory circuit so it's always closed when the car is running but then the ECU to text that there is an issue with the solenoid and presents a fault code. So now what I've resorted to is using an extra solenoid I got from the junkyard just to satisfy the ECU that it has one connected and then the second solenoid the one connected to the charcoal canister will be energized via accessory circuit I know this is a ghetto way to take it but I really need to pass emissions I was wondering if you've ever heard of anything like this before. Also as far as i can tell the intake manafold is connected to the charcoal box with to a diafram valve like ur picture but it has no eletrical conntion it has one vacume line is switched by an electronic pneumatic valve. Ive yet to find a pressurd sensor but there must be one somewhere correct?

very educative. Thank you regards

Nicely done.

good video, im impressed.

Great Work Brother

Great video!

I wish the manufacturer of the EVAP system made the system a little more durable considering the engine performance depends on it so much. My purge valve was stuck open and many tests needed before it was corrected. Thanks for your lecture, very informative.

Very good video, thanks

Thank you for sharing these ideas

An excellent video

Nice Job. Time to go troubleshoot.

Thank you! I hope you and your wife are doing good!

thank you so much you help me find my problem ...also causing a p0171 and a p0174 lean condition caused by a faulty canister vent valve solenoide...

Thank you for a wonderful video on this subject. What led me to your presentation is this. My 2006 Accord 4Cyl auto is showing P2422 error code "Cannister vent valve is stuck closed". I am trying to find out what to do including what parts to replace if any, to resolve this issue.

The most informative explanation of EVAP I've found. Question: where is the vent valve usually located. I understand the purge valve is located under the hood, attached to the intake system, which makes it convenient. Many thanks.

100th comment huh? Incredible video it's extremely informative and to the point. Awesome job and thanks this has really helped me understand things

This is a good video. Thank you. I have a question though... is it normal procedure for a car to run a Constant 13%(or any number )purge valve command after the car has reached operating temp? mine seems to.(and it keeps higher single digit trim #'s(not sure if this is what is causing this slightly lean condition))

Awesome explanation! Thank you! Only wish i’d watched before my buddy whose truck wouldn’t fill up right spent $1k on a new gas tank …

i have a 2007 Peugeot 307 2.0lt. my question is or comment is, my evap canister became unlodged the valve thats connected to it also separated from the canister its self, what can happen to the rest of the system, as in contaminants entering the system and messing things up. is there anything i have to reset?

This is a great video, thank you. I'm having a problem that i can't figure out. After refueling, my cars idle stumbles and wants to die for about 30 seconds. After that, it normalizes and runs great until next fill up. No issues putting gas in the tank and No CEL. I've replaced the purge valve and vent valve to No avail. Any suggestions where to look next?

Having a P0455 in A 2006 Acura TSX, replaced the gas cap with an OEM part. It still comes up once in a while like 3 months apart. Thinking of replacing the Vent Valve and Fuel tank pressure sensor. What's your take?

Very good explained thank. Need information regarding euro 1 to euro 7 diesel & petrol engines. Please.

Great video. Very clear especially with the diagrams. I have a question though. What would happen if your purge valve was stuck closed? I would assume that the vapors would continue to build up until something happened? Would the vent valve eventually be able to vent the vapors into atmosphere? Again great video!

Wau!. Great explanation there.My 2jz fse has two valves connected to the canisters. And they both have pipe connectors at the end of the solenoid.the immediately one sucks air through even when not powered and the later one does not. Which of these connectors is connected to the canister which is sucking pressure. Or can u connect them interchangeably?

Thank you for the video and thank you guys for the comments.

What an excellent review, thank you, I'm sub'd! There was one point you made at about 5:50 that is in conflict with another video I watched describing the process of purging. I don't know anything about these systems, so my question is innocently asked. It would seem more effective to purge by opening the purge valve and opening the vent valve, so that you are flushing the charcoal with clean air. If the vent valve were closed during purging there would be no way for air to replace the volume of gasses drawn into the throttle body, so the system would quickly develop a vacuum and not move much air. Are you sure the vent valve is closed during a purge? Perhaps it is a multistage process to allow both to happen in sequence?

Hi, do you have any idea, why my car fuel leaks from the tank when the tank is full after filling the gas. It leaks significantly until I stop filling the gas. I checked underneath; it is not from the charcoal canister, it’s from the gas tank. My car is nissan x-trail 2005. It is not leaking from filler neck vent though. We smell gas for few days after filling gas.

excellent review thank you very good

Great lecture but still thinking of the one way check valve in case air still needed to be sucked into the tank. This usually occurs on conditions of driving with empty tank all around so that vacuum exceeds.

Today I work in escalade 2008 , the tank not allowing to refuel , I changed the evap and still the same, then I found out all the pipes contacted to the evap system and the tank are full of small prices of coals . Could you tell me why this happened?

I appreciate the logical flow and explanation. I just cannot understand how a 200 Sante Fe 3.5 keeps lighting an evap leak and all but the symptom or problem experienced is if the tank is filled comply and not overfilled the engine at times will not start right away or if it does it takes about a mile for the engine to run at normal RPM. No mechanic has isolated and the only code is the Evap small leak. I have just changed everything except the canister because I did a test as stated by others and the tank pressure valve is original since the tank needs to be dropped to access. Your thoughts? Thx

Any ideas on a 98 civic with tank side code p1456 that will not be set if ambient temperature is above 70f? Code comes on mostly in colder seasons. Replaced filler neck, cap, bypass and 2-way valve with no difference

Hi. I am getting P0441fault in my Honda Accord 2017 saying purge malfunction. The same time it gives another fault P04F1 saying low purge flow detected. After watching your video, i opine that my purge valve is not opening or there might be some clogged hose. Can you please advise. Thanks

Thanks for vid can I take these valves out and apply 12 or some volts on each to see if they are stuck close or open. also how many volts I should apply

Hey 6speed., this was a very informative video, thanks. I had one question. On my 2004 Tacoma I found the line going from the fuel tank to the canister switch is slightly pinched, could this be causing my truck to stall randomly while driving, also stalls while idling?

Hi , my ECM says Fuels sensor B is faulty. Which one is (B) driver side or passenger side ?

Can you explain how a 2-way valve works in the EVAP system of Honda/Acura?

When engine is running and during purging fuel vapours enters the intake manifold. Wouldn't it make the air fuel mixture rich? Or even this fumes are taken into account by the ECU.

Hello I have a 2007 Chrysler town and country with a 3.3 L. The problem I’m having yes I have a small leak detection also it’s running a bit rough only win engine is warming up and also had to takeoff after that it’s sort of smooth up and runs like it supposed to as I’m running I can hear as though the gas tank is collapsing like loud thump sounds not sure what that is but when I come to a stop and shut the engine off I’ll here allowed squeak Sound I believe coming from the The atmosphere Release vent how can you help not sure what it is

So my cars pirge solinoild was bad i replaced it cleared the fault. I can heat my purge valve opening a closing while im at idle and driving a 25 mph. Ive replaces the gas cap as well. I need help.

So would a p0456 code be a canister vent or canister itself? Trouble filling tank, pump keeps shutting off due to pressure buildup. Seems like something is clogged not leaking as the code suggests.

Hey 6Speed! I have been plagued with a possible evap problem that I thought was other powertrain components and I am getting closer to understanding the evap system and this problem. It started one hot day and has got progressively worse to where the truck will start losing power and if you try to give it gas it just wants to stall/ drop rpm, if I let off it comes back in rpm's, as I continue under those conditions it Dies. If I let it sit for a few minute or hours it drive fine, If I let it sit overnight it runs great again. Lately since it has gotten cold it does not have any problems until the temperature gets back up to 50 degrees F, then it starts acting up again. Truck is a 2001 s10 4.3L 2 wheel drive automatic. Trouble codes are: current: P0128, P0341, P0440, P0449, P0453. Your thoughts would be helpful, course of action check out Vent Valve? Any help would be great Thank you!!

thank you very much

If monitoring on a ob2 scanner, What should normal vacuum readings be while running?

Your video is nice

Is it normal if the vent valve (normally open) is closed when the engine is off? I have a Toyota RAV4 01.

Have a 1993 chevy 3500 that was a diesel turn to 7.4 gas trying to vent the tank properly can you help

So I just pulled mine off to test it now it’s closed isn’t it supposed to be open when u pull it off?

My doubt is during the purging operation you specified that the canister vent valve is closed which leads to vacuum due to which the fuel is adsorbed from canister what governs the maximum vacuum. How is the amount of fuel going from the charcoal canister controlled. it might sound ridiculous but is the vent valve really closed during the purging operation because what i felt was the due to vacuum the air would be sucked through vent valve which would pick up the fuel from charcoal canister but is this happening or what is really happening during purging is only the fuel getting adsorbed no air please help to clarify my doubts..

I have always known that the vent valve is closed during evap system test and never during purging. Are all system the same?

Sometimes I smell gas when I get outside my 07 dodge caravan especially early in the morning after I’ve driven a couple minutes. Thinking vent value may be sticking open from time to time. Also have a “gas cap”msg on my odometer sometimes. What say you? Thx.

So the charcoal during venting (refueling / expanding temps) captures the fuel vapor only but any air goes to atmosphere without fuel vapors bundled with it?

We notice a raw gas smell at warm engine start. I replaced the injector o-rings hoping this was the issue. It wasn't. We do not have any engine codes set. I deliberately left the gas cap loose for 2 days and still no engine codes were set. Any ideas?

What happens if intake fuel port and purge port connections are interchanged??? This is serious question. 😐

For a 3 port vapor canister on an older car if you plug the purge port and only connect the vent line to fuel tank, will the canister still be able to breathe through the air inlet and function ok?

I have the p2422 code on my civic hybrid meaning that the vent valve is stuck closed. However, I have no issues refueling the vehicle. I’ve also noticed a decrease in gas mileage. The decreased gas mileage may be because of the p0420 code that I also have. Do you think the vent valve might not have an issue?

Thanks for the great tutorial. I have a P0442 code on a 1999 Saab. There are pinholes in the gas tank around the fuel pump area. I presume the tests would show up with a code due to those pinholes. Is that correct?

good video. i have a small doubt, from where does the air enter into the tank when fuel discharge into the engine.

nice sir

Won't the small leak cause gross leak as well ? If purge valve is open and vent valve is closed the leak could be in Charcoal canister or intake valve area. Compare to this when purge valve and vent valve both are closed the leak can only be in Charcoal canister. This means if there is no gross leak there cannot be any small leak. Please correct me if I am missing something.

My 2000 Silverado 1500 wont take any fuel. I pull the vent that connected to the canister and fuel was running out there. I need help

So, I have an idle issue after refueling. My engine dip in idle rpm for about a couple of seconds after startup, but only straight after refueling. Not otherwise. Have I gotten it straight if I say that my vent valve eventually is stuck in closed mode?

I overhauled my gas tank but now I have fuel spilling at the carbon canister under thermal conditions whether the engine is off or running at temperature..the only way to prevent it is to loosen the gas filler cap...any input is welcome!!

I have a 99 VW Eurovan and when putting gas in the car the pump shuts off constantly. No fault is shown on the dash. Was wondering what this would be indicative of. I think you note this would be a Vent Valve that is stuck closed. But would this mean that no fault code would show on the dash.

Hi on my renault clio 1.2 petrol [2014] I've got a fault p0444 evaporative emission system purge control valve open. I had a vac hose from inlet manifold split to purge valve. Replaced that. I have replaced purge valve and it's still coming up with same fault. I've reset ecu but still can't work out what's going on.

Good descriptive video. I have a 1 year old car (Subaru Impreza), over the past year it has stalled at least half a dozen times during slow speed acceleration (on hot days after hours of driving). Over the past few months, I've had a noise from the fuel tank area (on hot days after hours of driving). Last month, the workshop finally realised the fuel tank was over pressurising, causing this noise, saying one of the vent lines was kinked, and they fixed it. Well it's happening again/still. What part of this system could I check that would cause the fuel tank to over pressurise? The car is booked to go back into the workshop, but after numerous attempts, I think it's best that I just fix the issue.