return line for EFI conversion

I added my own return, and unfortunately, at the time I was thinking only of vapor return, to prevent vapor lock

I ran the car until the tank was quite low, then disconnected the front tube and allowed it to siphon into a can until the siphon "broke," IE the tank was essentially MT

I pulled the vent loose at the filler neck, and temporarily plumbed the 1/4" vent fitting out to "free air" with scrap tube and hose

I then got my MIG bottle (I use CO2 only) and plumbed the low pressure output into the fuel supply tube, allowing CO2 to flow into the tank, and pushing fumes out the vent which is essentially the top (filler neck) This tube, again, was extended out into "free air." I actually LIT this afire, so had a small candle like jet of flame, as the CO2 pushed the fumes out of the tank.

After several minutes, the flame went out. I then held a small torch near the tube opening, until no more flame of any kind would "try" to light off. I then knew that the entire tank was full of CO2

My Dart of course, is different than your Barracuda, on the Dart the front face of the tank is immediately behind the rear axle. I had cleaned off a spot on the tank, and after purging the tank with CO2, I took a sharp sheet metal awl and used a hammer to penetrate the tank, enlarging the hole with the awl to pass a piece of 1/4" tube. This was temporarily plugged at the end to prevent fumes/ CO2 from escaping.

Last, I simply silver brazed (hi temp silver solder) the 1/4" line into the tank. Now of course I wish I had installed a 5/16 or 3/8 fitting, because I'm running a Commander 950 injection system