LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

How do I revove or bypass the EVAP cannister.

Old Dec 16, 2006 | 01:47 PM
  #1  
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How do I revove or bypass the EVAP cannister.

My EVAP cannister faled and allowed charcoal to get sucked into the engine. Is also caused the fuel tank to build up excess pressure.

I want to remove or bypass this, I am not going to have another one fail and contaminate the vaccum line and my new engine.

I have removed the exisiting cannister, it has three lines connecting to it. The one line runs to the solenoid up front and the other two I have no idea.

Can someone provide instructions how to completely remove or bypass the EVAP cannister. Codes are not a problem, they will be removed via a new tune. I dont mind running this emmision as long as it does not include the cannister. Also I am also not opposed to running a vented cap.

Last edited by wrd1972; Dec 16, 2006 at 01:53 PM.
Old Dec 16, 2006 | 01:55 PM
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You might want to consider replacing the canister to avoid a fuel smell buildup at the back of the car.

If you want to disconnect the system, take the line from the tank off of the canister, and put a cloth over the end to act as a filter. Pull the harness connector off the eVAP solenoid, and put a resistor in to match the resistance of the solenoid = no codes (93-95 only)

As usual, Shoebox has info on the EVAP system:

http://shbox.com/1/evap_system.jpg
Old Dec 16, 2006 | 02:24 PM
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Put a cloth over the existing fuel tank vent, can I not just connect it to the existing vent? I cut the cannister open and the reason charcoal was being sucked through the line was do to the top sponge filter being breached.

What is this? A fresh air vent?



If the white thing is a fresh air vent, then can I just connect the fuel tank vent to the fresh air vent and call it quits? It seems to me I can even couple all three lines and still have some measure of emmisions without using the cannister. I can always install a new canister down the road if smell is a problem.

Last edited by wrd1972; Dec 16, 2006 at 03:03 PM.
Old Dec 16, 2006 | 03:25 PM
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Originally Posted by wrd1972
Put a cloth over the existing fuel tank vent, can I not just connect it to the existing vent? I cut the cannister open and the reason charcoal was being sucked through the line was do to the top sponge filter being breached.

What is this? A fresh air vent?



If the white thing is a fresh air vent, then can I just connect the fuel tank vent to the fresh air vent and call it quits? It seems to me I can even couple all three lines and still have some measure of emmisions without using the cannister. I can always install a new canister down the road if smell is a problem.
the white thing is a fresh air vent, but it only allows air IN, not out, if you cap the line you disconnect, you will take a while to fill the tank at the pump............
Old Dec 17, 2006 | 09:22 AM
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Where does the other end of the hose with the white vent (bulb thing) go, does it go straight into the tank or does it go to the canister?
Old Dec 17, 2006 | 10:24 AM
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Originally Posted by wrd1972
Where does the other end of the hose with the white vent (bulb thing) go, does it go straight into the tank or does it go to the canister?
right into the tank, it lets air IN, but not out, so you would be ok driving it, but it would take forever to refill the tank if you pluged the cansiter lines
Old Dec 17, 2006 | 12:16 PM
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Thanks.

Next question. Can I vent the fuel tank into the intake manifold rather than to atmosphere using existing plumbing? I would be simply removing the canister but still retain the emmision, it just would not be charcoal filtered.
Old Dec 17, 2006 | 04:33 PM
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No. You would subject your fuel tank to vacuum. You don't want to do that. The EVAP purge pulls fresh air in through the canister (connection 2 in Shoebox's diagram of the canister), desorbing the HC vapor out of the charcoal. It is not pulling vapor from the tank.
Old Dec 17, 2006 | 04:52 PM
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Originally Posted by Injuneer
No. You would subject your fuel tank to vacuum. You don't want to do that. The EVAP purge pulls fresh air in through the canister (connection 2 in Shoebox's diagram of the canister), desorbing the HC vapor out of the charcoal. It is not pulling vapor from the tank.
and it would still cause you a hard time filling the tank
Old Dec 17, 2006 | 07:56 PM
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So its either just vent the one line running from the canister or just replace the canister. If I had faith the charcoal contamination I would just buy another canister.
Old Dec 17, 2006 | 08:11 PM
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I've never heard of anyone else have a failing canister. Just replace it and call it a day.
Old Dec 17, 2006 | 08:21 PM
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Originally Posted by Javier97Z28
I've never heard of anyone else have a failing canister. Just replace it and call it a day.
Wierd, I have read about this problem a lot. The foam punctured letting the vacuum suck the charcoal from the canister and into the engine. I wonder if that for any reason contributed to my cylinder wall scratches?
Old Dec 17, 2006 | 11:26 PM
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Carbon particles in the EVAP solenoid is a fairly common problem. The charcoal does break down. But its not going to hurt anything, other than plug the line or the solenoid. If you're really worried about it (I wouldn't be), put a filter in the line. You probably get more carbon left in the heads from the combustion.
Old Dec 18, 2006 | 06:15 AM
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Originally Posted by wrd1972
So its either just vent the one line running from the canister or just replace the canister. If I had faith the charcoal contamination I would just buy another canister.
well, the old one lasted for 10+ years, think about it...........
Old Dec 18, 2006 | 07:12 AM
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Damn.. go figure I read this forum alot and never caught onto that...

Personally I want to get rid of all that **** b/c it looks terrible under the hood.

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