EVAP canister cheap fix

I had several EVAP related trouble codes pop on my truck awhile back (P043E, P043F, P2401, P2402 & P2419) & have been testing a cheap fix for the last 3000 miles with success. I'm going to attempt a half assed how-to with the intent to save someone the $650 it costs to replace the "carbon canister". Had my foresight game been stronger 3 months ago, I would have taken more detailed pics...my apologies.

*Disclaimer* This fix worked on my truck with no issues, however YMMV. I am not a mechanical engineer or a professional technician. I take no responsibility for any issues you may have from doing this on your vehicle. In my case, I had nothing to lose as a new canister cost $650 & I would have went that route if this didnt work. If you don't have the money to replace the canister, I wouldn't recommend doing this, as it is easy to damage. Proceed at your own risk.

-Make sure vehicle is off, in Park, e-brake set, wheels are chocked etc etc.

-Remove the charcoal canister from under your truck bed (appx 7" x 11" black box located just above & fwd of your rear axle). You'll need to remove 4 or 5 bolts...12mm if memory serves. Also there are several hose connections that are a major PITA to disconnect, be careful & it can be done with a stout dental pick & flathead screwdriver. Emphasis on careful...the clips break easily. There may be a much better how-to out there on removing the canister....I just didnt see it. Props if someone posts it up.

-Once canister is removed, move it around in all directions & see if you have any water or fuel in it (drain it out if possible). Now take it to a bench...your going to pressure test it next.

-Seal up the open hose barbs that you just disconnected with vacuum caps or other sealing media, leaving only one barb open (see pic below).

-When I pressure tested mine, I used a standard blow gun with a tapered tip from my air compressor. Anything that seals against the hose barb will work.

-Mix up a heavy soap solution in a spray bottle for leak detection.

-SLOWLY blow air into the canister until you see the top or bottom of the case rise slightly (or if you have time, attach a gauge to one of the open barb fittings to read internal pressure). If you have a way to regulate air pressure very low (<10 psi)....do it. The key here is to just introduce enough pressure to leak test (2psi is enough). I cant overemphasize this step, do not over pressurize the canister, it can be damaged easily.

-Spray your soap mixture over everything, all the connections, hose barbs, freeze plugs & fittings. Make sure to leak test the caps you just placed over the disco'd hose barbs as well... check your work. If you see any bubbles you have a leak. In my case, I had a small leak at the small freeze plug below the center hose barb (the barb you used to apply air from blow gun). I sealed my freeze plug up by covering it in clear rtv & covering it with a vacuum cap & cable tie (pic). I also replaced the small 1/8" I.D. line on the canister for good measure (pic). Seal up any leaks & test until your air tight. If you find leaks somewhere other than your temporary hose caps...that may be your EVAP system issue. Seal them up & proceed.

At this point I decided to "air out" the canister, as research indicated they can also throw codes if they become saturated in water or fuel.

-Remove all your temporary caps you used to seal hose connections.

-Blow air through the canister from one barb & ensure air flows out the others. Once you've ensured your no longer pressurizing the canister...blow air through each port for a minute or two in order to "dry" the insides. This was my theory & may be a complete waste of time, either way it appears to not have done any harm in my case.

*REINSTALLATION*

-I installed the reverse of removal with one exception: I thoroughly cleaned each hose barb & the inside of its adjoining hose (truck side) & inspected the sealing surfaces/ O-rings. Then I applied a very thin layer of silicone GREASE, NOT rtv.....to the contacting surface of each barb. I did this to improve the connection/ seal of each hose as my truck is 12yrs old & rubber tends to get crusty. Make sure you've reconnected everything, applied anti sieze to your bolts (you or your mechanic will thank you in 3yrs) & checked your work.

-After you've completed all this, reset your ECM via your OBD2 scanner or the negative battery disconnect method.

Job done. Now treat yourself with $650 worth of performance truck parts since you (hopefully) no longer have to buy a charcoal canister.

 

Was your codes on constantly? If I delete the codes sometimes it wont come one for a week or longer. I might try this.

 

Yes, my codes were on constantly. On my scanner they registered as 'Stored' & 'Pending'. The evap system bases its diagnostics off # of start cycles I believe...probably why it keeps popping up consistently after you clear the codes. Might be worth a shot to leak test & dry it out.

 

It's not on constantly. If I clear it out. It might not come on for a month or a week. It's weird. I think i will try what you did to at least rule that ou .

 

That is strange....you may have a very small leak that expands/ contracts with heat cycles or similar. If you pull the canister, leak test those factory freeze plugs real close!

 

@osidepunker

 

I feel like i have a different problem though. I dont have any codes. and I can put fuel in, I just have to pump it at like 1/3rd flow. Takes a while but I dont think its as bad as warrens truck was.

@Stewie suggested I try blowing out the filter by the filler neck. That'll probably be the first thing I try. Or I might try to replace it altogether

 

btw, OP I bought a evap canister on ebay for like $200 just fyi

 

Damn! Was it a takeoff?

 

yeah. There were a bunch when I shopped a few months ago

 

Good find, I'll keep an eye out if mine decides to blow.

Also, your fueling issue seems like a blocked vent? Not sure if it's on the tank top or in the filler hose line though.

 

yeah thats what I'm starting to suspect. I bought the evap canister because at one point it took forever to get fuel in. I had to dribble it. but then it sat for a few months and the next time I filled it, it was normal. I was confused but I got over it. 3 tank fills were normal, then it started filling slow again, but not stupid slow like before. The last 3 tanks I can fill it if I hold the trigger just under the first click. Its annoying and takes awhile but I dont think its the evap canister anymore

 

I’ve been having a similar problem. But I only get gas at Costco so it could be those pumps. But I found I need to have the fuel nozzle handle towards the gas door and it seems to be the best angle. I fill from the first notch on the gas pump handle. Anymore and it shuts off.

 

If I recall, there was a vent line plumbed through the evap can from tank. There is also a small port in the metal filler neck (where you put the pump nozzle). I think that port acts as an overflow...& is plumbed to either the tank or evap cannister (it's been awhile since I've looked). I'm wondering if you have a plugged/ liquid saturated line from either:
#1 the port in filler neck, or
#2 the vent line to/ from evap cannister.

-I noticed about a month before my codes hit that all the fuel pumps were shutting off late as I was filling up & spewing fuel down that filler neck port. I've started manually filling (not using the clip on nozzle) until I hear the fuel come up the neck...then stop, no more fuel in the overflow port. Maybe try disconnecting the lines & blowing them out?

Edit: I've also started leaving an air gap around the pump nozzle while it's in the filler neck (don't jam it all the way down). Seems to reduce the backpressure & assist in venting.

 

Yes, that what I have going on. Depending on the gas station, some of them I can leave it on one click and it will fill. Others I have to have it less than first click

Yeah I am going to have to start at the filler. Either #1 or #2 is a possibility I think

 

What causes this issue on the newer vehicles? In the past, the theory was Evap related problems were caused by fueling up right to the gas- cap port, is this still the case

 

I've been told that topping off (filling to max capacity and then adding more) will eventually saturate the charcoal canister and cause issues with filling.

 

^^ I believe that's about right. Some pumps pressure switches are calibrated a bit high as well, which will cause them to burp fuel into upper filler neck area & into drain port. When you hear the fuel start rising in the neck...just stop it a bit early.

 

@osidepunker
If you troubleshoot your filling issues & find out what the cause is...would you mind updating this thread?

 

yes of course. If I forget, ask me in a few weeks. I have some other work I have to do before I tackle this problem

 

Rgr that. Thank ya

 

So it hasn't changed over the years, I'll continue to stop filling at "first click."

 

Good plan

 

yesterday and today, the fueling issue began affecting me. went from no issues to can't even go slow....get about 10 cents of fuel at a time. tried at two different gas stations. and of course, it's snowing and cold. hopefully will be able to try blowing out the vent hose tomorrow.
weird thing is, as mentioned, this has not been an issue at all and i've put a ton of miles on the rig in the last 2 1/2 years. (about 51,000). i did four trips to denver and back over the last three weeks, that's a tank each trip (i upgraded to a 38 gln tank) and there were no indications until i went to fill last night.

 

haha I havent worked on the fueling issue yet. Its still a problem though. I have to hold the pump at just under the first click. Its super annoying, but I dont drive the truck that often

Anyways, I still have the used canister. Maybe I'll install it today

 

Apparently there is a TSB on trucks 2017+. I have a 2016 and finally got sick of the problem and took it to the dealership yesterday. The TSB says to replace the filler neck. The 2016 has the same part number for the filler neck so they replaced it.

haven’t tested it yet, but I’m hopeful it will work.