So, been a bit quite lately (probably a good thing for all ) waiting for bits for the car to arrive.

Got under the back of the car to check out the vent situation today. Car is '71 Dart and has the EEC (is that the right lettering?) pipe. Basically the extra pipe that comes up into the boot to catch fuel vapors and as I understand it, if they condense they flow back into the tank???

Anyway, looked at what is back there and here is what I found. Tank has obviously been changed at some point. Tank has a single vent pipe off the front which now loops around, runs through the slot in the frame and connects to one of the five fittings on the bottom of the extra tube in the boot. A piece of hose then comes off one of the other fittings and hooks to the pipe that runs to the front of the car where it connects to the breather cap. From what I understand, the vapors that would travel up to the front would be stored in the engine until the car is run and then would be sucked through into the inlet and burned off.

On the remaining pipes off the tube in the boot there are rubber vacuum type caps over them. These are in various stages of cracking and falling apart due to fuel vapor issues I'm sure.

So, double checked and by the picture on a website selling tanks the correct tank should have four tubes coming off the driver side which should have four hoses going through the slot in the frame and over to the boot pipe. Don't really have the extra $200 to change the tank back to the correct one so now wondering about hooking up an effective vent system. Does the four vent type system actually conserve fuel by returning it back to the tank? Sorry if I've got that understanding of the system wrong.

Sort of like the idea of having the pipe part to allow raw fuel to run back into the tank, but can't see the ability to make that happen. The concern is then, do I need some sort of valve to stop the flow of liquid fuel along the vent pipe if I just connect the tank's front vent directly to the pipe running to the front now? What about a roll over valve?

I'm thinking of taking off the vent to the breather and running the tank vent to a charcoal cannister that way I can run the carb bowl vent to it also and purge the lot using a purge valve. Anyone have any thoughts on this?

Thanks in advance for any help.

Cheers

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From Mopars to classic Minis and back to Mopars in 19 years flat!

Will work for roast chicken crisps!!

ECS. Evaporative (emission) Control System. EEC was Ford's Electronic Engine Control.
The ~upright vapour can in the boot originally connected to the vent pipes at each of the tank's four upper corners. Each of the multiple pipes entering the vapour can was a different distance from the top of the can, so no matter what angle the car was parked, and facing whichever direction, there'd always be a vapour vent at the effective top of the fuel tank with a path to the vapour can unblocked by liquid fuel. The outlet line from the vapour can runs the highest within the can — just barely below the top of the can — so only vapour should ever enter it. It was run forward to the engine compartment, where it connected to the engine crankcase via an extra fitting on the breather atop the rocker cover. The carburetor bowl vent was also ducted to the crankcase via a hose to a fitting on the body of the fuel pump. Thus, the fuel tank and carb bowl are vented to the engine crankcase, and fuel vapours deposited there are drawn off via the PCV when the engine's running. This was certainly an imaginative way to do it, but the '72+ system was not only simpler but much better.
That's a '72+ tank.
Somebody didn't understand how the original system worked (and can you blame them...?!) The '72 tank has a dome-top design such that liquid fuel doesn't tend to enter the vent line. This, together with a vapour/liquid separator valve, allowed the elimination of the multi-tube vapour can in the boot. If you don't want to try to find such a valve, which is harder than it might seem since many of the OE units are grommeted into the tank itself, it's fine to do it the way the previous owner did; you just need to use caps made out of better rubber (or replace them every so often).
Well, compared to the previous atmospheric tank venting, yes, any of these ECS setups will conserve fuel that would otherwise evaporate and be lost forever. But no, the '70-'71 multi-tube setup doesn't do a better job than the '72+ setup.


The difficulty lies in finding such a valve that can easily be adapted to your car. It's probable that the second one pictured on this page would do; you'll need to cleverly mount it in its upright position under the car in series with the vent line.
That's the valve we're talking about.
It's a jolly good idea. See here .

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Too many people who were born on third base actually believe they've hit a triple.

Thanks for the reply. Time to get to work then!
Cheers

_________________
From Mopars to classic Minis and back to Mopars in 19 years flat!

Will work for roast chicken crisps!!