# Charcoal Cannisters: Can you remove them?



## BeachBuggy (Dec 22, 2007)

I have a 95 HB 4X4 4 cyl. I was just wondering if any of you guys remove your charcoal cannisters. Is there a way you can just by pass it? Maybe just connect the hoses to eachother? Mine wansn't working right so I bought a new one for $100. After putting it in, I checked the new one and now it wont let air pass through it just like the old one. I don't know what the heck is going on! This all started when I realized what I think to be a good amount of pressure in the tank is released when I open the fill cap. thanks for any help.


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## nissannut (Jul 3, 2003)

You dont want to remove it. It vents your gas tank. The gas tank should be pressurized. You dont want gas vapors escaping.


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## BeachBuggy (Dec 22, 2007)

what would happen if you didnt have a pressurized tank, say if you didn't use a fuel cap? Would that have negative impacts? Right now I am using a fuel cap that has a pressure relief button and I have the button jammed open. I removed the charcoal cannister and just put a piece of filter over the end of the hose that leads to the throttle body. I know something is wrong because when the motor is idling, I don't feel any flow of air coming out of the tube that comes from the tank to the cannister. I just don't want something stupid to happen like my tank explode or implode. Thanks for your help.


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## smj999smj (Jan 1, 2006)

I seriously doubt that you had a problem in the first place...and if you did, you probably needed nothing more than a replacement Nissan gas cap. The carbon canister is used to store fuel vapors to a point when it can be sent to the intake manifold so it can be burned as fuel, rather than have those vapors escape into the atmosphere. Your 95's system is the old style system and relatively simple compared to what is used in 96 and later Nissans. 

Obviously, the fuel in your tank creates fuel vapors. The Nissan gas cap has a built in valve that relieves tank pressure at 0.5 PSI. Otherwise, the fuel vapors, under pressure, are pushed into the EVAP (charcoal) canister when the engine is not running. The purge control valve on top of the canister controls the flow of air and vapors back to the intake manifold; at idle, it is closed. Only a small amount of stored vapor flows into the intake manifold through the constant purge orifice. As the engine speed increases, and the throttle vacuum increases, the purge control valve opens and the vapor is sucked into the intake manifold through both the main purge orifice and the constant purge orifice. The vapor is pulled with fresh air that comes through the filter at the bottom of the EVAP canister. 

Even though the cap maintains only 0.5 PSI, opening the cap with the system under pressure can create a pretty significant "woosh" sound. My recommendation is to install a new Nissan gas cap and re-install the charcoal canister and let the system do its job.


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