When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I have bought two used vent valves and my mechanic installed them after being cleaned up. I still can only dribble gas from the pump into the tank otherwise at full flow it backs up. I know they don't make new ones anymore and I was wondering if a different vent valve from a later Camaro, Firebird or any other make will work. The gas tank itself is correct to the car but is an aftermarket unit. I will be putting the car up for sale and don't want to have the new owner face this ongoing problem.
Thanks for any help the membership can provide!! BobC
I've actually got an IROC-Z the same year and engine options as yours and I'm looking for the same vent valve as I accidentally threw mine away with the old sender . Where did you find those valves, used? Or if it's possible, can I buy your spare valve? I'll match whatever you paid for it and I'll pay for shipping.
Thanks....I will remove the valve and see if the tank fills up OK! Don't know why we didn't think of that! Also, I bought the valve used from David T's Camaro & Firebird in Canada. $65.00 plus shipping. Takes forever as it has to go through Customs!! www.davidt.com
Thanks....I will remove the valve and see if the tank fills up OK! Don't know why we didn't think of that! Also, I bought the valve used from David T's Camaro & Firebird in Canada. $65.00 plus shipping. Takes forever as it has to go through Customs!! www.davidt.com
$65.00!!!!!!!! That's bullsheet! If i had known, I'd woulda sent you one free. My God, everybody out there selling parts for these cars think they are going to get rich or something.
My mechanic just removed the valve and replaced it with the one that came with the car......I have cleaned it out but there is an additional part in it that looks like a white plastic thumb tack......that is missing in the YouTube video other than that it is the same. I did drive the car to the gas station early this am with the valve removed....gas went in fine! Anyone who wants the old valve can have it for free.....remember to take it apart and reassemble correctly.
I just took apart the valve that I bought from Canada. That "extra" part on this one is actually affixed to the metal/rubber small spring assembly. The one they are putting on now has the same "thumb tack" but it simply came loose from the assembly...hope it will work as it fits inside perfectly. Thanks, BobC
The gas tank itself is correct to the car but is an aftermarket unit.
BobC
That is likely the real issue.
The real purpose of the mushroom tank valve is to allow air into the tank. It will exhaust pressure but only at a higher psi then the CCP vapor control valve. There is no way it can relieve pressure at a low enough psi to allow fast filling of the tank.
Thanks RBob........with the valve removed I put a couple of gallons in the tank and it did shut the pump off a couple of times but did not overflow as it has done in the past. I guess I'll just do a leisurely fill each time! BobC
Your filler neck has a built in breather in it to allow for fill up. Might have some blockage in that. I don't know how to clean it out or even to check for that. It's built into the filler neck
I've actually got an IROC-Z the same year and engine options as yours and I'm looking for the same vent valve as I accidentally threw mine away with the old sender . Where did you find those valves, used? Or if it's possible, can I buy your spare valve? I'll match whatever you paid for it and I'll pay for shipping.
I've got a real nice clean working extra one I'll sell you. Get me your email address for pics and other info
Henry
Sorry to bring this thread back from the dead but I need a Vent Valve to pass emissions, unless someone has an idea of something else I can use in place of it. They do pressure tests and currently I am missing my valve so It holds no pressure and it failed. A guy told me I could cap the line and buy a vented fuel cap but I wanted to see if there another way or if anyone has an extra valve they could sell me. Thanks.
I just took apart the valve that I bought from Canada. That "extra" part on this one is actually affixed to the metal/rubber small spring assembly. The one they are putting on now has the same "thumb tack" but it simply came loose from the assembly...hope it will work as it fits inside perfectly. Thanks, BobC
that little thumb tack looking piece you are referring to has a built in spring actuator, that’s what makes the vent valve operate. It is a 2 way valve that opens to vent pressure and closes to hold vacuum. If that piece is loose or not connected then the plastic ring with the rubber seal on the bottom, it won’t do it’s job.
BTW....David T’s is stupid expensive, he operates out of Edmonton Canada, I live here and went to see him one day and quotes he gave me for other things are outrageous. Lol
Fitmeetsshan67.......I am in the process of sending you my old non working valve but if
you decide to take Henry's offer, let me know. Thanks, BobC
i have a question, I live in Canada so we don’t have emissions testing/ inspections here. If I take the UFO valve off my 91 gta, will that interfere with performance at all? I get a lot of pressure build up in my tank and when I stop at an intersection after about 30 minutes of driving, the rpms drop to about 300-400 and I have to shove the shifter into neutral as it almost stalls.
anyone on here with that issue and / or a fix? Thanks
Hi Tony,
What side of the little white "thumb tack" is the little spring on? The rubber side or the other side. Mine came apart but I have all of the pieces.
Thanks,
RTJ49
i have a question, I live in Canada so we don’t have emissions testing/ inspections here. If I take the UFO valve off my 91 gta, will that interfere with performance at all? I get a lot of pressure build up in my tank and when I stop at an intersection after about 30 minutes of driving, the rpms drop to about 300-400 and I have to shove the shifter into neutral as it almost stalls.
anyone on here with that issue and / or a fix? Thanks
Only thing I have hooked up on my tank is the supply and return. Both the vent and the vapor lines are left open to atmosphere. Runs just fine that way. If it's hot out you might smell gas and I've had it dribble a bit with a full tank on really steep inclines. Otherwise no issues at all.
With no evap system the UFO valve wouldn't do anything anyway since the vapor line is an atmospheric vent. So I just left it all disconnected.
[QUOTE=Spadercr;6376825]this is the bottom housing that normally breaks. You’ll have to reuse the guts and cap from your
can you print the cap where the tab breaks?
The part he printed isn't the part that normally breaks.... I'm confused. Anyway The top portion of mine was fine and is a different plastic than the bottom where the retainer tabs are located that always break off. I just decided to spend a couple hours this morning and make a new bottom cap that bolts to the bracket instead of clipping in - out of 6061 aluminium. And of course cleaned and inspected the guts and top cap - which were all in fine condition on this valve. I made about a 0.005" snap fit with the plastic top hat so once it's pressed below the lip it won't easily come out without some twisting and force applied:
GD
Last edited by GeneralDisorder; 08-29-2020 at 06:11 PM.
I recently bought a spare one and wanted to open it. After the first tab broke and a second looked kinda like breaking away I just took some oilspray and spayed from both sides into the part. Let it sit for a while and let the rest drain out. Now it seems to work again. Just have to mount and test it on the car...
I gave up trying to fix mine and went with a rollover vent valve from summit. So far no problems. And that issue with the tank not filling and the stalling due to intese vacuum pressure has stopped!
I would be interested in the aluminum piece. Nice work. What is the cost?
I992 z28 5.7 non-t-top car.
Thanks,
Rich
It was a one-off. I don't sell them. I built one for fun and to give people ideas. Selling them would not be economically viable. That one probably took me 4-5 hours to produce. At that rate I would have to charge $500 to make it worth my time.
that's how I set mine up. Its not the same as a regular vent valve but it totally fixes the issue. Someone said there might be a gas smell but I used a charcoal canister filter, cut it up and shoved it in the top part of the valve. no issues / problems at all and the car runs great.
can't find the original part so this will have to do.
I would be interested in the aluminum piece. Nice work. What is the cost?
I992 z28 5.7 non-t-top car.
Thanks,
Rich
In case I can find an original I didn't open up the mount hole. I think I just slid the valve through the hole, put the hose on and used a zip to lock it down securely, or it was pretty secure with just the hose. basically I can go back to stock should I find a good original unit...but this works fine so I'll probably just stick with this. No luck finding parts here in Hawaii.
Great news on the Hawk repro! Is this vent located under the car, between gas tank and back seat??? think I've seen something similar down there before. my gas tank is aftermarket and requires gas to be dribbled into it ever so carefully. always thought it was the aftermarket tank. seems like my vent is working cause when I park the car after driving it smells like gas down there, as if it is venting.
what do you guys think? vent or crappy tank install ?
Great news on the Hawk repro! Is this vent located under the car, between gas tank and back seat??? think I've seen something similar down there before. my gas tank is aftermarket and requires gas to be dribbled into it ever so carefully. always thought it was the aftermarket tank. seems like my vent is working cause when I park the car after driving it smells like gas down there, as if it is venting.
what do you guys think? vent or crappy tank install ?
Hi LiquidBlue ,
The way our fuel system works normally , you are never supposed to smell gas because it's supposed to be a closed system . In normal operation , a slight excess pressure in the tank should be vented through the charcoal canister , with the fuel vapors that would otherwise escape being trapped in the canister to be burned off shortly after the next start . If for whatever reason the pressure in the tank exceeds the charcoal canister EVAP system's ability to vent the air while trapping the fumes then the vent (valve) opens to prevent a dangerous pressure build up in the tank . The valve will also relieve excessive vacuum in the tank as well , allowing air in to prevent the tank collapsing if the EVAP system is not properly venting the tank while the engine is running (gotta let air in as fuel comes out to prevent a vacuum buildup in the tank) .
The bottom line is that anytime the valve operates to allow air either in or out , that is not a normal condition in a closed system .
Hey Orange - thanks for the explanation. I'll have to pay closer attention to where the gas smell is coming from and double check evap system. I do get the tank boiling problem. its hot down here.
Hey Orange - thanks for the explanation. I'll have to pay closer attention to where the gas smell is coming from and double check evap system. I do get the tank boiling problem. its hot down here.
Hi LiquidBlue ,
So now I guess I gotta ask , you mentioned an aftermarket fuel tank , were the heat shields put back in place when it was replaced (I think there are two pieces , if my memory is correct ?) .
There is definitely a heat shield there, not certain on the count. I made the mistake of letting another guy get my car fired up for the first time after 25 years. was too busy working back then. he did the gas tank. the tank always boiled, even back in 92.
flipped thru some old photos, found one with a glimpse of it and only see one on the passenger side. which makes sense, exhaust runs over there.
requires gas to be dribbled into it ever so carefully.
Fueling issues like that are the vent tube in the filler neck. I tried tweaking the neck on my second gen with a pry bar in the fill hole. I wound up crushing the little tube in there and have to fill slowly.
Fueling issues like that are the vent tube in the filler neck. I tried tweaking the neck on my second gen with a pry bar in the fill hole. I wound up crushing the little tube in there and have to fill slowly.
never have noticed the mysterious vent tube in any gas tank filler neck, is it pretty obvious if you look for it?
Very cool to have these made again! Props to Hawks. I ordered 3 for my cars and to have on the shelf.
For sure I can make these in my machine shop at home but it's important to support efforts like this. Hawks might be expensive to some but who else is supporting these cars? Good for them I say! Showing my support by making a purchase!
Very cool, Haven't been to their website in a while, looks revamped. The vent showed some things I hadn't seen before, like the door striker and hood latch, hood/hatch struts.
09-12-2017, 12:50 PM
. Where did you find those valves, used? Or if it's possible, can I buy your spare valve? I'll match whatever you paid for it and I'll pay for shipping. 
Hi LiquidBlue ,
