1975 Dodge Dart Fuel tank issue

1975dartsport360 said

I ran the tank to empty and was only able to put about 20 litres in. The tank on my car has a vent tube just above the fuel sending unit. There is a short rubber hose from the vent tube which runs to a steel fuel line which exits under the hood on the passenger side inner fender.

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My vent is exactly like yours except with the vent tube turned up in the corner of the firewall and inner fender, and I don't have any problems running the fuel full blast.
I really don't think that little tubing is enough to vent that fast anyway.

You say you can't get more than a certain amount in it.
Does it just refuse to take more, or does it take more if you go real slow?
On the Wife's Ranchero we have to hold the handle up so the fuel stays in the bottom of the filler neck so it can vent back out the top of the neck over the incoming fuel.
Otherwise it just shuts the handle off.
Have you checked to make sure your tank isn't crushed?
You might check the filler neck real good also, as someone might have put something in the neck to stop anyone from siphoning the gas out.