vapor canister question
 

Trying to figure out if my evap canister is bad. Unless I'm mistaken you should be able to blow through the canister, or are there check valves inside it?

It's been getting harder and harder to get gas in it, at this point I'm lucky to get a tenth gallon in before the gas pump shuts off. And now I'm getting P0466 code.

I tried blowing through the evap vent valve line with all other lines off and couldn't, canister seems clogged. I can blow through the line from the tank but it is hard to do and I can hear the gas bubbling in the tank, gas cap was off at the time.

Shouldn't I be able to blow through any of the ports through the canister??

I just went through the same issue a few months back with my 02'. It is not your vapor canister. If you have the 4-door model, it is the little box (cant figure on the name atm) mounted on the bed floor, right above the spare tire. If you follow the line from the mystery box to the vapor canister, and unhook it while fueling, you should be able to fuel up...no problem!

Replacing the box thingy was the easiest repair ever on that truck! It took all of 5 minutes, including dropping and raising the spare tire! And yes, on that specific part, you should be able to blow through it. If you cant, the internals are bad, not allowing the gas tank to properly vent, preventing you from filling up.

I will post if I remember the parts name...I just kinda ran into the Chevy dealer one day, went EHHHHHHH!, pointed to the part, and he knew what it was! LOL!

But yeah, it threw the Emissions code for me as well, for years...and it wasnt until my nursing scrubs were covered in fuel after a 30 minute fuel up that I investigated the issue...

GOOD LUCK!

How did you know what part to get in order to replace this box above the spare tire? If not, does anyone know the name of it? I get some occasional trouble with the pump shutting off before the tank is anywhere near full.

Thank you.

:icon_hyper:Evap. Vent Valve :icon_hyper:

Again, drop your spare tire, and look at the part. # should be on there! It takes all of 2-3 minutes, depending on the condition of your spare tire system. You are going to have to access the part anyhoo, to see if that is the culprit. (it is, but just to be sure). Blow into the connection, if you dont mind the subtle taste of fuel, and see if you are able to pass any air through the vent. If no, then its a bad part! Symptoms of a bad Evap. Vent Valve include, but are not limited to: Not being able to put gas in your tank, and the idiot light displaying P0446 for a trouble code.

My vent had a different connection than the OEM part that the chevy dealer gave me at first, so be careful when ordering. I would say just bite the bullet and pay the extra $10 at the dealer, and be done with it. For finicky parts like this, I don't trust online vendors. Too much hassle, and too much climbing under the car, in the dead of winter, after working a 12 hour shift :icon_doh:

Air blows through the evap vent valve easily, its the canister I can't get air through

IDK which lines have check valves on the Charcoal Canister?! In theory, the fuel vapors should travel in a one-way fashion. To the vent for disposal or purge for recycling. The vent is the only one connecting to the charcoal canister for storage though, right? I think the purge is a direct link from the tank to the motor, but I could be wrong (it happens alot). For you though, after my doctors appt, I will venture out to the ~~lazy man~~ and test theorys. I have been bitten by curiosity! (and I know my charcoal canister is kosher :icon_wink:)

The P0466 code is for the vent valve, or the purge valve (near the intake?!), either for faulty parts, or electrical faults to the parts. The fact that you are having issues pumping gas lead me to think mechanical failure of the vent valve (as in my case). The purge valve, to my understanding, allows you to recycle the vapors while you drive.

But in the meantime, if I cant get under my truck for any reason (im crippled ATM), do some trial and error. Unhook hoses until you can fill your truck without an issue. I would say check your fuel inlet pipe (filler neck) for its condition, but the ball inside the tube being clogged wouldn't throw a p0466.

And ANYBODY PLEASE step in and correct me if im wrong, but I would assume that the charcoal canister would have its own DTC # on the idiot light in the dash? Doesn't mean that the idiot light is always right. Stranger things have happened. :icon_shrug: PCM's do have hissy fits! I guess you could flood out the charcoal canister with gas if you overfill your truck, but you would smell a large odor of gas...and idk if we can clean our charcoal filters at all?

Update
Got ahold of a compressor and blew the lines out. Both big lines blew through one through the gas tank and the other through the vent valve. The small line to the vent on the manifold vent I believe did not, supposed to be closed perhaps. And all three ports on the canister blew through.

Was able to get in four gallons in at a time, much better than a tenth. And no ses light for 80 miles.

Hopefully 100psi didn't blow any check valves

Will try again in a week or so, and see if I can fill it in one pass again.

P0466 code wont show up with less then 1/2 tank of gas.

Filled the tank all the way, and will run it dry before I fill it again

P0446 code keeps coming back
 

I've been throwing parts at a P0446 code on my 2001 Blazer ZR2 for a couple of months. Changed Gas cap, Vent Valve, Purge Valve and Vent Solenoid. I removed and blew out the Charcoal Canister and blew out all the lines attached to all the parts I replaced. The code just keep coming back a day after I clear it. I'm out of ideas. Can anyone help?

I just replaced my evap solenoid on my 96 blazer. I been just taking it off and unclogging the charcoal out of it. I have replaced with new part now. But my question is charcoal suppose to be coming through into the evap solenoid. Is this normal. If it isnt do I need to replace my charcoal canister?

Box near the spare tire underneith
 

This box you are talking about is about 4 inches long by about 3 inches and retangler shaped and also bolts to the frame.It also has some wires connecting to it?

It's not normal for charcoal to escape from the vapor canister. Overfilling the tank is what causes the issue you're having. The canister is designed to trap fuel vapor in the activated charcoal. Overfilling allows liquid fuel to enter the canister, when that happens, the canister needs to be replaced.

Ya I belive that is the part 80 more dollrs err cars. I am unsure of is an overfill problem because I never fill up a lot just let the pump shutoff whenever. Is this part located underneath the rear driver quarter panel or below the air filtering am going to do more investigation today.

Located in the left rear quarter panel. The purge line from the canister to the purge solenoid, (on the engine) must be flushed and purged with compressed air, to get all charcoal particles out of it.

Thank you for the quick responses going to purchase the part today and make the install I will keep you posted.

Just one more quick question what is the proper way to blow out the lines?

Disconnect the vapor line from the purge solenoid and the canister. Squirt carb cleaner in one end of the line, and blow it out with compressed air until it comes clear.

Hey guys I'm running the P0446 code as well. I was pumping my 04 blazer 4dr and it stopped pumping it until my truck was filled? So I started forcing more fuel into the tank to top it off and I noticed gas started to drip from underneath? Then I recieved the code p0446 and am abit confused where I should check and replace first? Help! Emissions is due in a couple of days! Lol

See posts #13, 15, & 18.

Then clear the DTC's and perform the http://www.obdii.com/drivecycle.html and check for DTC's. If there are DTC's present, diagnose & repair them in the order they are retrieved. There is a flow chart for most DTC's here on the forum.

I too had the problem with the fuel tank pressurizing while pumping gas, which caused the gas pump nozzle to shut off if I tried to pump gas in any faster than a gentle squeeze at a snails pace. It took forever to put 30 bucks worth in the tank, unless I held the rubber nozzle boot back from the filler neck to allow the gas fumes/vapor to vent out. So... While having an airbag sensor replaced at my local dealership, I asked the tech what he thought the fueling issue was. He told me that it needed the "Vent Solenoid - part number: 25950499" replaced. Which I agreed to have him replace while it was on the hoist. This solenoid was in fact located underneath and in front of the spare tire. I was happy to put that problem out of my head, until the next time I went to the gas station, where I found that the problem was still occurring. This part didn't fix the problem. I was frustrated and didn't bother with going back to complain. Shortly after that, probably a month later I had to change out the fuel pump, located in the fuel tank because it was making a loud whining sound. I had hoped that the fueling issue would magically disappear with the replacement of the fuel pump, even though that wasn't the reason I replaced the pump lol. But it still wouldn't accept fuel without clicking off excessively. Two weeks ago I was doing a little reading here in the blazerforum, and after reading an overwhelming amount of thoughts and opinions regarding the "gas pumping" issue, I decided to order a "Vapor Canister" (Charcoal Canister) from Autozone - part number: VC4113. It cost me $150.84 total, with the free shipping to my front door. it came in 3 days. I installed it the following day. They're located in the left rear bumper panel. I had a quarter of a tank of gas at the time and was dying to find out if it had fixed the problem. Well Wudda Ya Know! It fixed the pumping problem. I was able to lock the nozzle handle and stand there with my hands in my pockets as the tank filled and then clicked off on it's own. I turned on the key and looked at the gauge and was happy to see that it had filled to just above the F. Yay! So that's what it was. I've put gas in a few times since then and it's still filling perfectly without any problem. By the way, I blew into the three ports on the old Vapor Canister and was surprised to find that there was No blockage. I didn't expect to be able to blow into them without finding at least one of them to be plugged. It wasn't the case. I hope this information will help someone else. I know how frustrating it can be to feel as though you're ready to give up and let the dealership bend you over a barrel lol. Good luck.

WOW. Unless the system was diagnosed properly, which I doubt either one did, they're probably both wrong. If the EVAP system is not repaired properly, the vehicle will not pass an emission inspection, and the SES light will come on. Never mind the Federal fine for tampering with the emission system, which you are ultimately responsible for because it's your vehicle!

Fact: Cold air intake systems and the Airaid TB spacer, are both a total waste of money. There is no improvement in performance, or fuel mileage, with either one.

I understand and you're probably right, the spacer is most likely useless; ouch! I knew I would get picked on for that one ;) However some cold air intakes have been shown to improve performance. The cheap ones on eBay are probably a waste of money but other higher end kits like K&N and Volant with heat shields (etc) are good products otherwise they would be required to state “for entertainment purposes only” on the box.

This truck has cost me thousands of dollars to maintain and fix/replace parts that are designed to break so new ones need to be purchased (entrapment?) so I have lost a lot of faith in GM and federal guidelines too. If I have to alter the workings of my truck in order to save myself from going bankrupt and going nuts at the same time then so be it. I don’t believe any additional emissions caused by my Jimmy are going to bring about the apocalypse. If I win the lottery tomorrow then I will gladly convert my GMC to burn cooking oil and take a trip across Canada smoking water-vapour cigarettes with Captain Planet ("he's our hero!" does anyone remember him?) One interesting thing in my mind is why hasn’t the government outlawed old K5’s or Scouts? They surely spit out more emissions than my poor little 2000 vortec? Could it be because those trucks will require new parts at one point in the not too distant future and feed the automotive market yet again? No that's not it, most likely the emissions-act was passed after these vehicles were produced therefore its okay to turn a blind eye, sorry mother earth! I wonder what the emissions are like at the mud bogs with all those modified truck’s with 49” tires that spit out black smoke and block out the sun?

Do a little search on you tube "cash for clunkers". You will see some beautiful car's going to a sad and untimely end. Politics aside evap canisters can be re-loaded with activated charcoal from the pet store.

It just takes some time and ingenuity.

Depends how bad you need to get away from the wife.

I rebuild everything, only so much Bravo a man can handle.

The throttle body spacer is designed to "swirl" the inlet air so fuel mixes more completely with it. There are only a couple of problems with that theory: After the air passes through the spacer, it enters the plenum. Any "swirl" that was created is lost in the plenum. The second problem is that the fuel is added at the intake port, downstream of the plenum, and the spacer. As the air & fuel mixture is drawn into the cylinder on the intake stroke, and then compressed, the mixture is "swirled" due to the "Vortec" design of the combustion chamber, (hence the name Vortec V6). Engines that are carbureted or have throttle body injection, might experience a very slight difference in performance using the spacer. On a port fuel injected engine like yours, it does nothing.

Keep in mind that fuel must be atomized and vaporized before it can be burned efficiently. After the air passes through the cold air intake, it's heated in the plenum, (before the fuel is added to it). As the air is being drawn into the cylinder, the fuel injector opens; atomization & vaporization occur instantly. Cold air intake systems might sound nice and look pretty, but that's as far as it goes ;)

EDIT: Using those two mechanics, I can see how you spent thousands on repairs & maintenance ;)

Code p0455
 

Hi i'm Chris and i have questions. i'm new here so i apologize if i overlooked the answer somewhere but here's my issue. (i'm also handy but i like to know what i'm doing before i do it with as much info as possible)

04 blazer 2 door 2wd code popped up P0455. just curious to what i can check out before i just start replacing everything at random as it can be pricey. i want to believe it is the charcoal canister but idk how to tell if that's the problem either. Any help is appreciated greatly!

P0455 is defined as a large leak (>.030") in the EVAP system. Locating leaks in the EVAP system can be a time consuming process. Could be any one, or more, of the following: purge solenoid on the engine, vent solenoid on the crossmember above rear axle, purge canister, fuel tank, fuel pump O ring, fuel tank pressure sensor, fuel filler neck, fuel cap, or any of the associated lines and hoses. Start with a good visual inspection. A smoke machine is the tool of choice, and a hand vacuum pump can be an invaluable tool for locating leaks. Best to check each individual component, one at a time. Apply vacuum and watch for vacuum to hold, or deteriorate. The most common problems are: fuel filler neck rusted out, vent and or purge solenoid stuck or leaking internally, fuel filler cap not sealing properly against filler neck. Here is the GM diagnostic flow chart: https://blazerforum.com/forum/diagno...0-370-a-53332/