Difference between gas tank return line vs vapor line?

[ScottH]

Can anyone shed some light on this? I have a 72 which had the original tank removed and relocated to under the bed. I would like to return it to the original location. I picked up a tank from a 72 parts truck which has the EEC lines on it. Can anyone tell me how the extra line connect - to the fuel pump as a return line or to a vapor cannister?

My truck is a 402 engine with the fuel pump with the return line but does not have a cannister. Should the return line located on the gas tank upper left hand corner be connected to the fuel pump return line?

Any info is greatly appreciated.

Thanks!

[JimKshortstep4x4]

On our 72 AC cab the return line, (from the fuel pump) is routed to the gas tank sending unit which has the two fittings on it. If your tank has another
nipple on it it should go the the vapor canister.

The nipple should be on the passenger side of the tank.


Jim

[StingRay]

A vapour line is open to the top of the tank. A return line actually drops down into the liquid fuel like the pick up does. So a return line will usually enter into the tank through the same opening the pick up and sender are in. Droplets of fuel falling through the vapour and into the liquid can generate an electrostatic charge in the tank and possibly an explosion. Make sure the return is really the return!

[cdowns]

there should be the nipple on the passenger side of the tank and that goes to a loop thing in back of the passenger door pillar then the hoses run to the charcoal cannister

[ScottH]

Many thanks to everyone for the info, now I understand the difference.

So my next question is, can I use an EEC tank in my truck which didn't have a cannister? Figure I could just block off the vapor line outside the cab, not the best but does anyone see any problems?

[JimKshortstep4x4]

If you use a vented cap, you should be able to block the nipple at the tank.

Jim