Did I screw up my fuel system?

[Grec]

So... pretty shortly after I got my 73 Challenger years ago, I decided to redo the entire fuel system and set it up like a factory 440 six-pack.

Here's what I have:

70-style tank

3/8 sending unit

3/8 fuel line

1/4 return line

Six-pack vapor separator

OK... here's where I think I may have screwed up... I still have my original 73 filler tube which doesn't have a vent line that dumps out at the frame rail.

The car runs good, but DOES have a weird random hiccup / backfire in the carb that I have never been able to get rid of. This may not have anything to do with the tank / fuel line setup... but then again, I suppose it might.

I guess the real question is... even with the return line and vapor separator, do I still need some kind of vent line? What kinds of problems might not having it cause?

[brads70]

What gas cap do you have? Vented or non-vented?

When you take off the gas cap ( especially on a hot day) do you hear pressure releasing?

[Grec]

It's aftermarket and I'm pretty sure non-vented.

And no... I don't recall hearing pressure releasing.

[brads70]

I'd say it needs to be vented somehow? Mine (1970) has CA emmisions and has 4 vent tubes coming off the tank going to a tube " thingy" in the trunk?

[Chryco Psycho]

if you have the 70 tank it should have the vent nipple that would connect to the line into the trunk , if the nipple is open it will still vent , & may spill fuel when full , what did you do with the nipple , is it covered ?
Are you running a six pak ?

[Grec]

I don't recall hooking up anything other than the fuel and return lines... Where on the tank is this nipple? It's been awhile since I installed the tank.

And yeah... I'm running a six-pack.

[Chryco Psycho]

I don't recall hooking up anything other than the fuel and return lines... Where on the tank is this nipple? It's been awhile since I installed the tank.

And yeah... I'm running a six-pack.

As I recall it is high up on the right side near the filler neck as the vent line just went up to the filler neck

[boxfox]

I did this project last year, replaced all the same times you've replaced, but I never got a new vapor separator or return line, I just removed the return line completely. I still put the 4 hoses to the old vapor separator and then out the other side I put a small length of hose running off to the side in between the vapor separator and the fender, its been working out fine for me like that.

And by vapor separator I mean this. Posted a picture because there seems to be alot of confusion as to what these are suppose to be called and or what the actual function of them is.
I simply did away with the smog canister up front also.

[jimynick]

Has anybody got a good one of these? Mine is rotted, badly and I'll need to replace it. Sorry and not trying to hijack the thread, just thought it was appropriately timed. Thx. Ian