Charcoal Vapor Canister Delete
Senior User
Joined: Aug 2011
Posts: 178
Likes: 1
From: Manchester, NH
If this is just FUEL VAPOR, what exactly is the point of having the canister? Why couldn't the vent line run direct from the tank to the TB? And, further more, if this were the case, why would a purge valve solenoid be necessary? Why couldn't the canister and the purge valve be eliminated altogether and just have a line running straight from the tank to the TB?
Cargo Master
Joined: Jul 2009
Posts: 2,538
Likes: 53
From: Des Moines
The function of the canister is to store vapor to be used by the engine at a later time. The function of the purge solenoid is to allow the engine to use the vapor when told too by the computer. They cannot be bypassed in the manner you speak because engine vacuum would create negative pressure in the tank, and suck raw fuel into the engine.
I did not know [or realize, because it seems an obvious problem] that the engine vacuum would cause that to happen.
Elder User
Joined: Apr 2015
Posts: 613
Likes: 0
From: Boston, KY
Just came across this thread and thought I'd resurrect it and add an interesting perspective. I am a chemist in the rubber industry, and a lot of what we make goes into gaskets. The reason the a lot of car companies are using charcoal canisters is because the acid that is formed when ethanol is burned causes the valve cover gasket and head gasket to harden and crack. My absorbing the vapors, the gaskets are being protected from acidic vapors. The original design may have been for environmental concerns, but it turns out that it is also necessary if you're burning ethanol diluted gas. On the other hand, if you go with FKM or HNBR gaskets, they are not susceptible to acidic hardening.
Elder User
Joined: Apr 2015
Posts: 613
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From: Boston, KY
Absolutely. Make sure you use modern FKM rubbers when you're jammin' it up the tail pipe. Might also want some heat tape, but that's a different issue.
FTE Legend
Joined: Jun 2006
Posts: 31,927
Likes: 1,494
From: Ottawa, Ontario
If this is just FUEL VAPOR, what exactly is the point of having the canister? Why couldn't the vent line run direct from the tank to the TB? And, further more, if this were the case, why would a purge valve solenoid be necessary? Why couldn't the canister and the purge valve be eliminated altogether and just have a line running straight from the tank to the TB?
Let's ignore the fact that eliminating them will trigger codes. I want to know what the practical effect on the engine is [performance or otherwise] if this were to be done. And I want to ignore the codes part because some pre-computer engines also have charcoal canisters, so for my part I am not concerned about the computer aspect of it.
New User
Joined: Apr 2015
Posts: 8
Likes: 0
Had a 96 Cherokee that had not one, but two steel tanks implode because the yahoo owner before me bypassed the system and ran the vacuum line direct to the tank return line. Running down the highway at 70 and the thing dies, get out and am looking around under the hood and hear this loud bang and see fuel pouring out from under the back.
Second time around, I removed the entire fuel system on one from the scrapyard just to see what was different and found mine was missing the canister.
Second time around, I removed the entire fuel system on one from the scrapyard just to see what was different and found mine was missing the canister.
Freshman User
Joined: Jul 2007
Posts: 44
Likes: 0
I have a thought [AND IT SCARES THE HEEBIE JEEBIES OUTTA ME!!!!!], because I have been wondering about this as well.
If this is just FUEL VAPOR, what exactly is the point of having the canister? Why couldn't the vent line run direct from the tank to the TB? And, further more, if this were the case, why would a purge valve solenoid be necessary? Why couldn't the canister and the purge valve be eliminated altogether and just have a line running straight from the tank to the TB?
Let's ignore the fact that eliminating them will trigger codes. I want to know what the practical effect on the engine is [performance or otherwise] if this were to be done. And I want to ignore the codes part because some pre-computer engines also have charcoal canisters, so for my part I am not concerned about the computer aspect of it.
Depending on the answers I am considering doing this to my 91 F150- and this could be an option for the OP as well.
If this is just FUEL VAPOR, what exactly is the point of having the canister? Why couldn't the vent line run direct from the tank to the TB? And, further more, if this were the case, why would a purge valve solenoid be necessary? Why couldn't the canister and the purge valve be eliminated altogether and just have a line running straight from the tank to the TB?
Let's ignore the fact that eliminating them will trigger codes. I want to know what the practical effect on the engine is [performance or otherwise] if this were to be done. And I want to ignore the codes part because some pre-computer engines also have charcoal canisters, so for my part I am not concerned about the computer aspect of it.
Depending on the answers I am considering doing this to my 91 F150- and this could be an option for the OP as well.
1st Gear
Joined: Feb 2025
Posts: 1
Likes: 0
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