There is a check valve on the vent line.

Look under the car, fuel tank is behind the back seat. You will see 3 lines.
Fuel supply
Fuel return
Vent line

I don't think they can be fixed but you can try to soak it in some kind of solvent.
You can temporarily remove it until you get a new one. Just don't fill the tank all the way.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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