71 Duster Fuel vent

-
If you have a single filler tube, you use a vented cap to vent it.

If you have 2 tubes in your trunk, you use a non-vented cap. The gas tank is vented through the second tube via some rubber hoses.

On the early single filler tube's, there is a small vent tube attached to it. You can use either cap for this tube..
 
Problem I posted about in another thread is with my home built vented gas cap after filling the car and hittign the highway on a HOT day It vented fuel that ate the pain on the back of the cap and melted the paint all down the car. The tank has a vent nipple that's currently plugged off.
 
so what would happen if you left the vent tube intact in the trunk and switched the filler tube to a regular vented cap style? anything or nothing at all?
 
Are there different filler tubes as well? Thatmight be my problem as well. The car had a fuel cell and the PO put in a junkyard tank fuel filler tube etc but didn;t have the vent tube to go with it.
 
Johnny Dart said:
If you have a single filler tube, you use a vented cap to vent it.

If you have 2 tubes in your trunk, you use a non-vented cap. The gas tank is vented through the second tube via some rubber hoses.

On the early single filler tube's, there is a small vent tube attached to it. You can use either cap for this tube..
Click to expand...


OK....I'm dumb and will ask.

What does the vented cap look like versus the non-vented cap? They look so much alike........How can you tell?
 
6pk2goDemon said:
OK....I'm dumb and will ask.

What does the vented cap look like versus the non-vented cap? They look so much alike........How can you tell?
Click to expand...

Well let me see if I can explain this.
A non-vented cap is flat on the inside. Nothing to it.

A vented cap has a round metal piece that measure's about 2" with a hole in the middle of it. Basically there is much more to it then a non-vented cap.

If you ever look at caps on E-bay, you can see the difference.

Wish I was a little better at explainig it, hope this helps.
 
71Duster said:
Are there different filler tubes as well? Thatmight be my problem as well. The car had a fuel cell and the PO put in a junkyard tank fuel filler tube etc but didn;t have the vent tube to go with it.
Click to expand...

yes there are 2 different filler necks. this might have been your problem. the original 71 fillerneck for a california emmisions car w/ the extra tube in the trunk is going to have a different cap. this cap is only going to fit the neck for that cap properly. a non emmision car will have a neck with a regular cap. the regular cap will be very loose on a emmision neck and leak. you would have to find the original cap for that style neck to make it fit properly.
 
So the big question in life with a non venter filler neck, and a Homemade vented cap whats the best way to fix the issue of the major fuel venting on a hot day?

Would a proper vented cap be better? Or running a vent life off the upper vent nipple on the tank?
 
i would try the proper vented cap first since it would be the easiest to do, and since your paint got messed up already. if it works great. if not then go for the vent line off the tank.....
 
So I found a member here who has a vent tube, I see it has 5 tubes comeing off it. What are they all used for?
 
71Duster said:
So I found a member here who has a vent tube, I see it has 5 tubes comeing off it. What are they all used for?
Click to expand...


The five tubes go to a special gas tank system specificaly for California cars.
It was called Vapor Saver System. Unless your car came with this I would avoid it.
 
Alright, I had just put a plate on the hole in the floor, the car was built for Canada so I doubt it had any emmissions on it.

That being said I can't seem to find a vented cap. Wondering about building a vent for the plugged off nipple on the tank itself.
 
If the cap is vented then can to tank vent tub be pluged?
 
Heres the tube in question.

IM000518.jpg


If Im not mistaken it was used on 70 Cali emmision cars and all 71s. My 71 Scamp and my 71 Dart bolth had it,
 
Well I haven't made any headway in this issue yet.

I have a cap like the one on the left but still had to drill a hole to make it vent.

My filler neck is a plain jane old tube with nothing comeing off it.

The tank has no multi nipples etc except one single tube that is capped just above the sending unit.


Not sure what I should be looking to do here. Run a hose up off the vent above the sender to a higher point under the car if possible? Look for a better cap or a different filler tube?
 
The cap on the left is vented.

That is all you need.

You do not need to drill it. It is vented.
 
FWIW, my '70 had a nipple near the top of the filler tube and a hardline that ran back down the outside of the tube and through a small hole in the filler tube to floor gasket. The end of the line actually just ended inside the frame rail. That's it for venting.

It would be easy enough to drill a hole near the top of the tube (stuff a rag inside to catch filings) and thread or JBWeld a small hose nipple in the hole. Connect a rubber vapor line and route it down through the trunk extension and out the hole in the drain plug.

I did something similar to this when I modified my fuel filler. In the pic you can barely see the brass fitting near the top of the filler tube (before lines were installed).

Or just use a working vented cap, as suggested :)

completedfillerimg.jpg
 
Well my vented cap wasn't venting as noted by the massive whoosh of air when I pulled the cap off each time so I guess it may have had it's issues.
 
You must log in or register to reply here.
-

Back
Top