Vapor canister/return line

[highspeeddirt]

   I'm in the process of putting a new fuel tank on my 74 challenger. I was wondering could someone give me some suggestions on the fuel return line/vapor canister? I really don't want the canister in the engine compartment, but I don't want vapors in the engine compartment either. With that said, what kind of suggestions would y'all have for the return line and the line from the vapor separator without causing any issues? My return line is on my sending unit.  Thanks!

[Aracer]

Put a tube over the vapor line where the canister is hooked and run it up under the intake open to the air. or to a carb vapor nip at the fuel bowl or air cleaner. Not legal but neither is a hot cam.

[burdar]

Why don't you want to use the charcole canister?  Looks? 

[highspeeddirt]

Why don't you want to use the charcole canister?  Looks?

Yeah that's pretty much why. Not to mention I don't have one, and don't really want to buy one.... Lol I'll run one if it's the easiest/less problematic choice. Just would like to see what other options I may have. 

[Jamiez]

I picked one up for around $40 off eBay.  A little cleaning and some rattle can work and it was good as new.  You can rebuild them with the filter stuff from an aquarium shop if you need to

[burdar]

The charcole canister is probably the easiest way to do it.  It adds no weight at all and once cleaned up, they aren't really ugly IMO.  It is an emissions device but it doesn't cost any HP to use one.  Why vent gas fumes into the atmosphere if you don't have to. 

The small blocks never had a fuel sending unit with a return nipple.  Cars that did also used a vapor separator can.( mounted up by the fuel pump I think)  You could use the stock 1/4" vapor line as your return to the tank.  Just use one of those fuel filters with the nipple coming off the side to connect to the vapor line.  Then connect the other end to the sending unit. 

You would then need to run another vent line off of the vapor separator that's on the shock x-member into the frame rail.  I'm pretty sure that's how the tank was vented in 1970...just a vapor line into the framerail.

[highspeeddirt]

Well, got go to digging around and found a charcoal canister amongst the parts I got with the car. It has a screw in one of the ports.  Anyone have any pics of theirs mounted in their car? I'll probably go ahead and run it. Did 74 models have the return line on the sending unit?

[burdar]

Someone with a 74 needs to answer that.  I thought only the BB cars used a return line to the sender.

Here's the canister...Mines a little too flat.  I need to mist it with SEM Landau black instead of Trim black.  This is a 73.  I've got a picture of a 74 somewhere.

[highspeeddirt]

I soaked the vapor canister in evaporust for 2 days and still can't get any air to blow through the vapor line. The four nipple are opened up just can't get anything through the vapor line nipple. Any suggestions? Thinking about soaking that nipple full of PB blaster then another round of evaporust.


Update: did the PB blaster and resoaked evaporust for about an hour and it has freed up the check valve, but still seems pretty restrictive. I would imagine it would be somewhat restrictive with a check in that small of a line, but how much? All it's venting is vapor so it doesn't need flow like a wide open line right?

[burdar]

It's kind of a strange valve.  You would think that if you blow one way it would allow air flow...then if you blow the other way it would restrict flow...but that's not how it works.  Plug three of the four nipples on the one end with your fingures.  Now suck and blow into the nipple that connects to the vapor line.  You should hear and feel the valve opening and closing.  It only allows air flow in the middle of its travel.  When you blow into it, there will be some air flow until the valve seats.  Then when you suck on it, there will be some air flow until it seats again.  Does that make sence?

[highspeeddirt]

It's kind of a strange valve.  You would think that if you blow one way it would allow air flow...then if you blow the other way it would restrict flow...but that's not how it works.  Plug three of the four nipples on the one end with your fingures.  Now suck and blow into the nipple that connects to the vapor line.  You should hear and feel the valve opening and closing.  It only allows air flow in the middle of its travel.  When you blow into it, there will be some air flow until the valve seats.  Then when you suck on it, there will be some air flow until it seats again.  Does that make sence?

Yep! Makes total sense. And that's the way it's working, so I guess I'm good to go. Thanks for that explanation. Now I feel confident enough about it that I'll probably hook it all up tomorrow. Thanks!

[Aracer]

Here's a question, about the 1971 fuel return line, did it have the check valve too, or is that new for the vapor storage canister system with no fuel return?

[burdar]

Cars with a fuel return used a vapor separator up by the fuel pump.  I don't know if it had a valve inside it or not.  71's used that big tube in the trunk for the tank vapors.

[Aracer]

That check valve sounds like a ball that rolls back and forth to meter and slow over flow, when on a hill with a full tank on a hot day. The fuel has run out of the bottom of the canister; in 1974, I went through that with the wrong locking gas cap.
     I want to use that vapor line for a return instead, but I still need to vent the tank, so I'm thinking I need to add the 1970-1 cuda tank vent tube.