Gas filler neck vent

[acmack]

I have 2 GPA gas filler assys. One has the vent tube routed to the outside air and the other back into the gas tank?

Are the differences due to an early and late style?

David

[acmack]

I guess some photos would help?

Notice how one of the GPA filler neck vents pass through the wall of the filler allowing it to vent to the outside and the other keeps the tube inside of the structure venting into the tank.






Is one an early model and one a later? If so which is which?

David

[bobassel]

Hi David,
In my opinion the filler neck with the tube inside is the normal version.
It is possible that the one with the outside tube is the early model, but I think this is not
a good because it is hard to keep the water out with a rubber seal on the rear deck.
Maybe David Welch can tell you if his early one had the same "early" model?
It is for us all interesting to know if this is early or late
Bob

[acmack]

I can see how the internal tube design helps in rapid gas filling but not in relieving gas pressure expansion developing in the tank, for example, on a hot day. The external vent design would accomplish both.
I agree though that if the rear deck took on a breaking wave that water might wash backwards into the gas tank through the external tube design. But then again if the filler cap and tank were properly sealed sea water could not push it's way in through the external vent tube in a full bolus anymore than you can rapidly fill a gas tank without a vent tube.

David

[GlennV]

I would think that the external vent design would allow gas vapors into the hull, which could cause an explosion hazard.

Therefore to me, this would be an 'early' design ....

Fyi, i have the internal tube design in my GPA.

Kind regards,
Glenn

[acmack]

The open tube design I posted vents above the rear deck and to the rear of the cabin. Unless you are driving backwards or the windspeed is from your stern at a greater rate than your forward speed venting is moved away or straight up into the atmosphere.

Where does gas tank pressure vent from in an internal tube design?

I would not think from the tank fittings as that would fill the rear bilge with gas fumes where the batteries are located!

In modern car designs the gas tank vents to outside air but fumes pass through a gas vapor filter/trap first.

David

[acmack]

So, no one else has seen or has an external vent type filler neck?

David

[Cees]

David,
It looks like a fillerneck from a Dodge commandcar WC56/57
Cees

[Cees]

It looks they cut the tube, that is why the rubber hose is long.