My buddy brought his 72 Roadrunner by today so I can help him along...I am surprised it is running to be honest. So many things wrong with it. He didnt get get a FSM so I have nothing to go off of for the Fuel line supply/return. I am shocked to say the least. He showed up with fuel pouring out of the tank area. I assumed it was the fuel sending unit seal but that component is on the passenger side of the fuel tank. I let it cool down ans I crawled underneath and the first thing I see is an alligator clip just gripping the gas tank loosely on the passenger side. Next....I drew a picture of how the lines are plumbed and how I think the lines should be plumbed. In Figure A where is says "atmosphere" its actually a fuel line, 24 inches in length and zip tied around the top shock tower and then just hanging out. Is figure B correct? Anyone have a diagram showing the correct emissions and fuel layout of the vehicle?

Car: 1972 Roadrunner, 440 4spd

I have done it both ways in the past, have used the vent line as a return. Didn't do anything different to vent the tank and it vented and ran hard like that for 6 years.

Your second drawing is correct and is how both of my cars are now. Vent line needs to windup in the engine compartment at the top of the engine.

They stopped going in the trunk with the vapor separator in 71. 72 was underneath.

I have never used the return on the sending unit as a vent, no way that'll work well.

The way figure A is seems hokey to me....its just 24" of fuel line...zip tied around a shock mount....and underneath the rear axle hump...its just hanging there at the same level as the fuel tank...

Where exactly does the vent line go at the top of the engine? I don't think I have seen that before

The line you have labelled "to trunk", I believe actually goes to a vapor line to the charcoal canister in the engine compartment. The charcoal canister is mounted far forward on the passenger side inner fender, almost up against radiator yoke.
Although with 440, it may be different - mine was 400-auto-CA emissions. Mine also didn't originally have the return line, though 440s did have the fuel/vapor separator mounted near the fuel pump, with the 1/4" return line, per the FSM.
If the charcoal canister has been removed/tossed, the fuel vent line should vent high enough to avoid liquid fuel coming out, though I might avoid the trunk, if possible. FSM says the tank should have pressure/vacuum relief cap.

Member 72RoadRunnerGTX might know for sure.

Alright...I went and checked the car....There is a special place in hell for people who sell a car online and don't hook up any of the provisions.

I found the fuel vapor canister. The "Fuel line" is "connected" I will have to verify that line tomorrow. The other three lines are just hanging out zip tied to each other and dumped by the rear of the manifold.

Many many thanks for that MoparMarq...

if there is no vapor separator at the rear close to the tank...should I get him to buy one?

If there are only two lines (and I will check that tomorrow) can I just hook up the return line from the fender mounted canister into the return line of the fuel sending unit?

If the previous can be performed...what can I do with the 4-port emissions manifold on the rear shock cross member?

71 and the first part of 72 the vapor tank is in the back of the left rear fender well. Sometime during 72 production they moved the tank to the shock cross member. I have a couple 72B's with the fender well tank.