Non venting gas cap for storage

[tonys_shelby]

It seems like I have so much fuel evaporation because I don't drive the car especially over the cold months, I'm wondering if I just install a non evap. Gas cap for storage. Does anyone else do it?  I use Sunoco Optima.

[jk66gt350]

I also don't drive my car that much.  I typically only go through 2-3 tanks of gas a season and store my car for 5-6 months of the year like most others in the northeast.  I have never experienced or heard of any significant evaporation while a car is not used.  How much fuel is going unaccounted for?  Anybody else experienced this?

[Bob Gaines]

It seems like I have so much fuel evaporation because I don't drive the car especially over the cold months, I'm wondering if I just install a non evap. Gas cap for storage. Does anyone else do it?  I use Sunoco Optima.

Do you realize what is involved with switching out a pop open gas cap on a 67 Shelby? You may want to find out before trying to switch caps because it is a lot of work.

[67 GT350]

Can't you just pop it open and get a small gas cap and install it with the flip open, open? It is just for storage, thus your not driving it.
Also, interesting topic, my 70 Boss can loose up to a 1/2 tank in no time.

[Bob Gaines]

Can't you just pop it open and get a small gas cap and install it with the flip open, open? It is just for storage, thus your not driving it.
Also, interesting topic, my 70 Boss can loose up to a 1/2 tank in no time.

Nope. That is because the pop open ring sets on top of the filler neck eliminating clearance needed for a typical cap to twist,lock and seat. I am sure you could rig up something like a big cork or the like to close off the neck. Taking off the ring is what is so labor intensive.

[Side-Oilers]

I have never heard of, nor considered, fuel evap during storage with a vented cap.

Has anyone else here experienced similar?

I live in SoCal, near the beach, so temps and humidity levels are relatively constant throughout the year.

[tonys_shelby]

I think part of it is the Sunoco fuel but in 2 months 3-4 gallons loss.  I've figured out a twist on cap that I can get to go flush to the pipe and have the pop cap open. Yes just for storage. No don't want to remove the tail lights etc to remove original cap.

[67 GT350]

Can you show us in pictures?

[Side-Oilers]

Maybe your kid/nephew/friend/neighbor is taking it out without you knowing? 

[557]

"Sleepdriving"?Better check the odometer to be sure.

[tonys_shelby]

Pictures...what do you want a picture of?  The gas cap? 

[tonys_shelby]

Hey I think it's weird too that's why I bring it up. First time using this fuel in a storage type situation. And wondering if anyone else runs into it. I put a piece of rubber ( thin ) between the cap and Filler neck and the vapor built up enough pressure when I opened it later that day it popped opened and it the vapor rushed out. Have heated garage so temp is consistent for most part.

[shelbymann1970]

So I had a half of tank of gas in my 69 Mach1 since Spring of 2015. I used stabil but will drain the gas out before I fire up the car in the next month(5-6 year engine bay detailing). So under the evaporation are you saying of the 10 or less gallons that was in my car in 2015 I should be about empty on what is in the tank? Yes, I have the same vented system with the pop open gas cap. Gary

[67 GT350]

Pictures...what do you want a picture of?  The gas cap?

If you find an answer.
Has anyone seen the repro pop down gas cap that gives the option to conceal a screw on cap? I wonder if that would work on a Shelby? It would be completely wrong though. but it would allow you to leave it on year round where you flip the cover down and take the cap off. I got one of these for my 67 GT and I did not use that option.

[tonys_shelby]

Shelby man, it's hard to say I've never ran into this before which makes me think it's the type of fuel. 67 Gt350, I have seen those before not real interested in something to use all the time just will put on a regular type for storage and leave it popped open.