Vapor port on fuel tank

[canyncarvr]

My '73 Duster fuel tank has a hose fitting on the top, presumably for the vapor capture setup that was originally on the car.

That fitting is connected to a vapor separator inside the tank? As such, the fitting could NOT be used as a return line?

Not for EFI, but for a fuel return to help lower fuel temps...something to plumb my bypass Holley -841 regulator to.

Thanks.

 

[67Dart273]

You are correct, it IS in fact the vent. The caps on evap controlled cars are not truly vented. They are "pressure/ vacuum relief" caps, in other words they relieve pressure in both directions.

 

[canyncarvr]

Yes, it is a vent line that went to the OEM canister in the engine bay...but at the tank it runs THRU a separator (inside the tank), so it can NOT be used as a return fuel line?

 

[67Dart273]

No, because it IS the vent. The only way I would know is either
A leave it as a vent and create another port for return, either mod the sender or braze or somehow put a port into the tank. They make mechanical / gasketed fittings that you may be able to install through the sender hole

B...Modify the fuel filler tube AKA put a vent fitting in the tube and duplicate the 69/ earlier type vent. Those ARE simple and work well