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Fuel Tank Ventilation... fairly simple question

Old Mar 14, 2002 | 08:07 PM
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From: New Fairfield, CT
Fuel Tank Ventilation... fairly simple question

Okay my tank didn't seem to be venting. I would open the gas cap and a bunch of pressure would release (or there was a vacuum in the tank.. not sure which). Anyway, I raised the rear and found that little plastic one way valve for releasing pressure. I figured it must be clogged or something. So i clean it up, etc.. and blew in it.. and I found that it takes a pretty good big of lung pressure to get it to vent. Should it be this hard? It seemed to me that it was too difficult so for the meantime I have a (new) clear fuel filter for a lawn mower on the end of the vent tube so that the tank is venting all the time, but no crud can get in there. Is it okay to run with the tank like this? Also the evap crap is out so that line is just venting up front.. any thoughts on this?

Thnx

Patrick DeGrosse Jr.
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Old Mar 14, 2002 | 08:19 PM
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From: Loveland, OH, US
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The purpose of that valve is to hold pressure. Your tank is designed to be pressurized. So not only is your system normal, but it would be defective if it didn't do that. In CA for instance, the smog ***** actually verify that your gas cap holds pressure, and you can't license your car if it doesn't.
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Old Mar 14, 2002 | 11:09 PM
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Really? It just didn't seem normal to me that I would hear all sorts of gas escaping when i loosened the gas cap. But if you says it's normal then I guess i'll be putting that valve back on.... thnx

Patrick DeGrosse Jr.
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Old Mar 15, 2002 | 07:58 PM
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john5.7 87Iroc's Avatar
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From: Pineville, NC US
Car: An '87 Italian Retard Out Cruisin'
Engine: LS1 install in progress
Transmission: 4L60e
Axle/Gears: 9 bolt
Where can I get this valve.???? Mine seems to be venting all the time. My tank no longer holds any pressure. I cant seem to find it anywhere.
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Old Mar 16, 2002 | 03:38 PM
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I had to jack the back way off the ground to get under there. Once you do that... you're gonna see a ton of hoses and metal lines running up into seeminly nowhere.. but they actually go to the tank. One of these will have a little gray plastic thing on the end and mine was held on with a hoseclamp. Just pop it off and give it good cleaning in some PB Blaster or the like. BTW Mine is back on now.. thnx guys.

Patrick DeGrosse Jr.
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Old Mar 16, 2002 | 04:29 PM
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john5.7 87Iroc's Avatar
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From: Pineville, NC US
Car: An '87 Italian Retard Out Cruisin'
Engine: LS1 install in progress
Transmission: 4L60e
Axle/Gears: 9 bolt
Thanks. I kow where its is, I should have said where do I buy it? I cant seem to find anyone that knows where I can get a new one. I will take it off and spray it down and maybe that will do it hopefully.
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Old Mar 16, 2002 | 04:41 PM
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Dealership I guess.. but cleaning it should help.. rust prolly keeps the valve from opening. Oh and when u blow in it to check it.. you're gonna have to REALLY blow hard.. least thats what I had to do.

Patrick DeGrosse Jr.
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