I've got a 71 Duster that I bought with the tank and filler tube out of the car because the trunk center was rotted out. Now that I've fixed the necessary, I ordered a new tank matching the one that came with the car - a single vent model. I went to install the tank and noticed there is nothing to connect the vent tube to. I looked in the parts book, and there is no vent tube for the car, just a single fuel line running front to back.

Can someone recommend the right way to vent this thing? I don't have the part in the trunk to use the 4-vent tank, and am not interested in correctness at all. I just need to be able to fill the tank and drive the car without an explosion hazard from venting fumes in the wrong way.

Thanks for any help with this.

That's in the service manual

http://www.mymopar.com/index.php?pid=109

I don't see any vents except for the California emissions type tank (vapor saver). That's not what I have. But it does make me think I should look at a 70 model book because I don't think the vapor saver package came around until 71.

You say you have a 71 Duster. FSM says all 71's have it. The 70 FSM says only certain ones have it. So if it's a 70 without ECS then you don;t have it

This looks like what I need - a different filler tube and a vent tube. I hadn't thought to just look at 1970, doh!

This still doesn't show the vent nipple, at the very top of the tank above the sending unit, but I would simply run a hose from the tank vent over the vent tube and be done.

Now to find the parts I need.

It's a 71 but it doesn't matter if I have the ECS or not at this point. I guess it had the right filler tube, but the wrong tank, and is missing the ECS tube. Then I turned around and bought a replacement tank of the same wrong type. That explains why I don't have a vent setup on the car.

Now that I've found how the 70s are run, I know what I need to hunt down to make it work.

Probably just need a vented gas cap for your make and model.

Good luck with that. When I got my 51 the gas cap didn't vent, you could hear the tank oil canning as the sun heated it up. Bought a new one, did the same thing. Turns out the new caps have some sort of pressure valve to vent both pressure and vacuum. The original was essentially just a hole to atmosphere. Had to weaken the spring retaining the pressure to get it to stop oil canning the tank. Maybe an NOS one might work though.

As for the vent nipple, I think that's an aftermarket thing since the tank in my 65 has the same vent setup as that 70 one the OP posted. No nipple above the sending unit.

I've read that if the tank itself isn't vented then it's hard to fill the thing up. Makes sense.

If I can't find a 70 type filler tube, I'll just make my own vent tube from some 5/16" fuel line

FWIW after some study I gave up and ordered a vented cap based on your advice, and this note in Ehrenberg's auction: Great upgrade for pre-'73 A-bodies: Two-way check valve solves tank venting problems forever. All vent lines on tank can be capped off!

That is exactly the type of cap that made my gas tank oil can as it heated up and cooled off. I'd pass on it, not to mention tha tif you have any kind of emissions inspections capping off the vent lines would likely fail the visual.

That should work if the venting is properly calibrated. A two way valve should only allow air flow in and out of the tank above a small pressure value. That keeps the tank from venting while the car is just sitting in the garage but allows excess pressure to escape.

Yes, it should, but the two caps I tried didn't so I had to take it apart and calibrate the pressure release. Might just be my application so YMMV just be aware is all.

There is no emission testing to worry about here in WV.

The 70 cars with ECS (non-vented gas cap, extra trunk vent tube, and the unique gas tank) are California only so not super common..

Here some more info if anyone cares..

https://www.allpar.com/fix/fuel/evaporation-control.html

But he says it's a 71, which if I am reading the info right all of them should have ECS?

Yes, 1970 ECS was CA only, and in 1971 they all had it.


And the 70-71 ECS fill tubes and gas caps are unique as well. .