65 Cuda Gas Tank Vapor return line

[PiP Squeak]

I’m working on a 65 Barracuda that was garaged for the past 20 years. The previous owner started the process of removing the gas tank but was unable to finish. I finished putting the new tank and sending unit in, but since the previous owner had already removed the hoses I am not sure how the vapor return lines were connected originally.

On the fuel gauge/sending unit there is an extra connection that looks to me like a return line connection. The overflow/vapor return line on the filler neck (the one that’s bent like 2 Z’s and an S) goes from the top of the filler neck, where the gas nozzle is inserted, through the rubber grommet in the floor board to? (I have pictures if it would be helpful.)

• The previous owner said that he didn't remember any rubber hose or steel line connecting the two together (the filler neck overflow tube and the 2nd connection on the sending unit). Are these supposed to be connected? If so how, with just a section of rubber hose?

• If not, what connects to the end of the vapor return/overflow tube after it goes through the grommet in the trunk, and where does it go?

• AND, then what connects to the 2nd nipple on the sending unit?

I’ve got a pretty good shop manual but it has no info. on these connections.

My guess is that the two are somehow connected together, it just seems really strange to me that it would all be done with a rubber hose 2 ½ feet long, (specially after they went through major brain damage to make the steel line in the truck work). Is there supposed to be an additional steel line that I may be missing that runs between the two and is connected at each end by short sections of rubber hose? This seems to make the most sense to me. Or are they even supposed to be connected?

Can anybody help me figure out where these connections are supposed to go?
Pictures would be great.

 

[clifcuda65]

It goes though the grommet and that's it... It vents to the outside... that's the way they were way back in 1965...

 

[67Dart273]

You need a shop manual.

The previous guy put an aftermarket sender in with an extra fitting. There WERE NO vapor return systems except for the street hemis and the ??70 sixpack engines.

The emissions carbon can system is a different system, and those were not installed until "some" in 1970 (California)

ClifCuda is right--the vent comes out of the filler, goes up, back down, through the grommet, and ends right inside the frame rail.

This 66 Plymouth manual does not cover Barracuda instrument panels or other "special" Cuda stuff, but here's a 66 manual:

http://www.mymopar.com/downloads/servicemanuals/1966_Plymouth_Service_Manual.zip

http://www.mymopar.com/downloads/servicemanuals/1966_Dart_Coronet_Service_Manual.zip

In here is a 65 Plymouth manual, again, no special 'Cuda stuff

http://www.forabodiesonly.com/mopar/showthread.php?t=244981

 

[clifcuda65]

Tank Vent

 

[BillGrissom]

I agree with all above. The after-market sender you have is better, so keep it. For now, just add a short section of "hose w/ bolt" to plug the 1/4" tube off, or I think you can get a rubber cap to clamp over it. Down the road, you may want to run a tube from a fuel filter vent to that port (read posts here). I use that in my 65 for a return for my EFI pump.

 

[fig]

I use that in my 65 for a return for my EFI pump.

Did you use an external pump?

Thanks

 

[PiP Squeak]

I thought about that, but it just didn't make any sense to me to capture the fumes and or overflow in the return tube of the filler neck only to dump/vent it on the ground under the car.

Think it wouldn't hurt anything to just hook the two together via a rubber hose?

(Vapor return to the tank)

 

[67Dart273]

I don't think you understand. The tube in the diagram above is the VENT It MUST be to open air, or the tank will either have internal pressure or a vacuum, depending on temp, etc.

All these cars had that type of vent until 70 for some cars and 71 for all cars when the "carbon can" system was implimented

What the second tube is useful for is a "vapor return" system, using such as Wix 33040 --5/16-- or 33041 --3/8-- fuel filters. These filters have a 1/4" fitting which has an orifice, which you install so the 1/4 fitting is at the top (air/ vapor bubble.) You run a 1/4" (or larger) return line from there back to the second fitting on the sender and it constantly "fights" vapor lock

The emissions control / carbon can system in later cars is a completely separate deal. It replaces the simple vent system (open) and vents all vapors into the carbon can, where they (it says here) are periodically flushed back into the engine.

Here:

http://www.forabodiesonly.com/mopar/showthread.php?t=183956

 

[clifcuda65]

I don't think you understand. The tube in the diagram above is the VENT It MUST be to open air, or the tank will either have internal pressure or a vacuum, depending on temp, etc.

Yeah, what 67Dart273 said... else you will have problems!!! Take a can of pop, put a straw in it, seal the opening "around" the straw so no air can get in... now suck real hard... the can will collapse inward if you suck hard enough and/or you won't get much fluid out... Do you really want your new metal gas tank to do that? (IF, your fuel pump is powerful enough...) Else your engine starves for fuel !!!

I've never seen anything "dump" onto the ground from my cuda's vent tube! It vents air in while engine is running and fumes out if it's hot... The old car's fuel system will function fine... even if the EPA is not happy... but then again, they want to crush these cars anyway !

 

[RedFish]

Most early A owners never complain about vapors leaking. Their most common complaint is actual fuel backsplash at the modern gas pumps.
Good luck with it.

 

[PiP Squeak]

Okay, that makes sense. I never thought about it venting air IN, I was only thinking of venting fumes/gas out. I'll cap off the nipple on the sending unit.

Thanks for all the help!

 

[BillGrissom]

Did you use an external pump?
Thanks

Yes. A Walbro with 3/8" inlet & outlet hose fittings in my 65 Dart (search for post w/ photos). I plan the same for my 64 Valiant. I have used various pumps in my 65 Newport. Originally, a Holley gear-rotor from a Projection 2-D kit (TBI), later a Holley radial vane (blue pump) I upped to 18 psi relief, a Ford V-8 external pump (1980-90's generic, $50 most auto parts), and currently a Walbro for Euro cars (Bosch Jetronic MFI) w/ banjo fitting outlet (buy at DeLorean site). I use the later only because I got 2 new ones for $15 ea on ebay. I originally had the Newport pump in the rear, but hated that, so moved to the engine bay where it works fine, and same in the Dart.