EVAP Charcoal Canister Removal Modification

[Booby1323]

Hey guys, I've been having issues with my EVAP system for a while. The issues started with a slow filling fuel tank, and after attempting to fix that a while back... I ended up with a slow filling fuel tank, multiple leaks in the system, along with the occasional "tighten gas cap" message. Long story short, rather than continue down the wormhole to find my original problem, and my new EVAP problems, I had BlackBear performance delete the EVAP system from the computer when I had them do my engine tune.

So I have had no engine lights or issues since having them do that, but my tank still fills slow and I still get the occasional "tighten filler cap". So before it gets painfully cold and I have to stand at the pump to fill up, I thought Id try to see if I can remove or modify the system to vent properly and not throw the loose cap message.

One solution as I understand it is to simply remove the charcoal canister and my fuel tank would fill normally, but would the computer see a low pressure and throw the "tighten fuel cap" message? Could I remove more than just the canister with desirable effects?

After learning more about how the system works, im guessing my original issue was probably the purge valve... If I was to replace the purge valve could I take the line from the tank to the charcoal canister and the line from the canister to the purge valve, and connect them together to bypass the canister and send the gas vapers straight to the stock vent?

I guess when Blackbear "deleted" the EVAP system, they just programmed the computer to never open the EVAP solenoid, so the engine never draws the fumes from the charcoal canister and therefore the OBDII system never sees these pressure issues to throw the engine codes. But the physical pressure blockage still impedes filling up the tank all while the I'm guessing the BCM senses my small leaks in the system and thinks the cap is loose.

I've tried to learn about how the system works and I think I have a general idea, but I wanted to see if anyone else had any insights or experience on how to get the fuel tank to vent effectively and safely? I realize this is not the proper way to fix this issue, but also if I could just get around the slow filling and gas cap dash message then it would be one less system to worry about upkeeping and it would be truly deleted. Making the truck just a little simpler to work on the future.

 

[swathdiver]

Hey guys, I've been having issues with my EVAP system for a while. The issues started with a slow filling fuel tank, and after attempting to fix that a while back... I ended up with a slow filling fuel tank, multiple leaks in the system, along with the occasional "tighten gas cap" message. Long story short, rather than continue down the wormhole to find my original problem, and my new EVAP problems, I had BlackBear performance delete the EVAP system from the computer when I had them do my engine tune.

So I have had no engine lights or issues since having them do that, but my tank still fills slow and I still get the occasional "tighten filler cap". So before it gets painfully cold and I have to stand at the pump to fill up, I thought Id try to see if I can remove or modify the system to vent properly and not throw the loose cap message.

One solution as I understand it is to simply remove the charcoal canister and my fuel tank would fill normally, but would the computer see a low of pressure and throw the "tighten fuel cap" message? Could I remove for than just the canister with desirable effects?

After learning more about how the system works, im guessing my original issue was probably the purge valve... If I was to replace the purge valve could I take the line from the tank to the charcoal canister and the line from the canister to the purge valve, and connect them together to bypass the canister and send the gas vapers straight to the stock vent?

I guess when Blackbear "deleted" the EVAP system, they just programmed the computer to never open the EVAP solenoid, so the engine never draws the fumes from the charcoal canister and therefore the OBDII system never sees these pressure issues to throw the engine codes. But the physical pressure blockage still impedes filling up the tank all while the I'm guessing the BCM senses my small leaks in the system and thinks the cap is loose.

I've tried to learn about how the system works and I think I have a general idea, but I wanted to see if anyone else had any insights or experience on how to get the fuel tank to vent effectively and safely? I realize this is not the proper way to fix this issue, but also if I could just get around the slow filling and gas cap dash message then it would be one less system to worry about upkeeping and it would be truly deleted. Making the truck just a little simpler to work on the future.

Interested as well. The whole system deserves to be thrown in the trash. I reckon the solution to refueling is to install a larger vent line. Someday I'll put those K&N breathers on the valve covers or run downdraft tubes as well!

 

[Booby1323]

Interested as well. The whole system deserves to be thrown in the trash. I reckon the solution to refueling is to install a larger vent line. Someday I'll put those K&N breathers on the valve covers or run downdraft tubes as well!

I agree with that, it seems like a relatively simple task to manage these gas fumes, yet the whole system is so unreliable and susceptible to dust. If there is a way to safely remove the whole system and throw it in the trash I might just go that route. I bet a larger vent line would help, but I'm thinking that the a purge valve would still be required either way in order to have a way to close the vent and build pressures so that the computer doesn't think the gas cap is loose. I wonder if the computer still attempts to operate the purge valve even tho I had @BlackBearPerf "delete" EVAP system?

 

[Booby1323]

Edit: double post

 

[swathdiver]

I agree with that, it seems like a relatively simple task to manage these gas fumes, yet the whole system is so unreliable and susceptible to dust. If there is a way to safely remove the whole system and throw it in the trash I might just go that route. I bet a larger vent line would help, but I'm thinking that the a purge valve would still be required either way in order to have a way to close the vent and build pressures so that the computer doesn't think the gas cap is loose. I wonder if the computer still attempts to operate the purge valve even tho I had @BlackBearPerf "delete" EVAP system?

I think all of those features in the computer system should be disabled. If BB can do it, I'd have him send me an updated tune in a heartbeat!

 

[Fosscore]

Interested in this, however I just replaced all 3 components of the EVAP system from the purge valve, vent solenoid and vapor canister. No more PO446 code. I blew out the line and got rid of the pellets.

Although I did just get a TIGHTEN GAS CAP message today and filled the tank on WOT without any issues.

 

[Booby1323]

So I was doing a little more research on people removing EVAP systems from other vehicles. I read someone with a older Silverado saying that if you unplug the electrical plug on the purge valve under the hood, then the computer will get no signal at all from the EVAP system. I also read that if you run an open fuel vent through a charcoal canister and out to the atmosphere, the charcoal canister will still help suppress fuel vapor smell and will help act as an anti-rollover valve by not letting liquid fuel through it. I only found that interesting because I assumed the fuel vapors had to be trapped in the charcoal canister for a extended period of time to stop the smell. So removing the charcoal canister is probably not the best solution.

So with those two ideas in mind and assuming the computer and EVAP control system are similar to the that of a Silverado, I'm thinking theoretically you could unplug the purge valve plug and any other electrical plugs in the EVAP system, and computer would have no means of sensing any loss of vacuum in the EVAP system. So the computer wouldn't have any input telling it to throw the "Tighten Gas Cap" message and in my case, engine codes that are triggered by the EVAP are already deleted as well. Then Id remove the vent solenoid and splice together the two hose ends that were attached to the solenoid so that the vent line runs straight from the charcoal canister to the original vent.

At that point I'm pretty sure you could consider the EVAP system truly deleted other than just getting the system tuned out of your computer, which is already done in my case. You probably could skip removing the vent solenoid and splicing the vent lines together by just removing the purge line from the charcoal canister and then the tank would vent right from that port on the charcoal canister. But I think it would probably more correct to completely remove the purge line and purge valve between the charcoal canister and intake, plugging the hose ports on the charcoal canister and intake in the process and doing the vent solenoid bypass. That way fuel cant somehow drip out of the charcoal canister if gets saturated with fuel and if you end up in a rollover the charcoal canister would help keep the fuel tank contained I think.

So that's my best guess on the best way to truly delete the EVAP system without getting the gas cap message, smelling gas fumes, and still safely venting the tank. I'm hoping I have time to try all that this next weekend and I can report back if my tank fills faster and i dont get any gas cap messages. In the mean time does anyone see any flaws in that plan?

 

[Big Mama]

interested in the outcome.

 

[Rocket Man]

I’m interested too although I just replaced all 3 components and in the process found and fixed a kinked plastic line so I think I fixed my random issue. I do believe the system has been removed on my bagged 08 Silverado that has an aluminum fuel cell because come to think of it, I haven’t seen a charcoal canister under there so it must be possible.

 

[Private Eye Guy]

I had a similar issue, mine would either fill extra slow or not at all... stopping after a gallon or so. I replaced the entire evap system and gas cap for good measure. Problem solved. I did the work myself, so it wasn't costly. My trucks an '08 with 210k on the clock. Hope that helps you out.


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