Fuel venting, Venting system Options

[Petepat]

I have a 72 1.7L with twin carbs, when moving the fuel pump to the front I noticed the return fuel pipe had been terminated presumably because it is no longer required. Question do I need the venting system, expansion tank, carbon filter and all the pipework, morden cars don't have this? I live in France by the way not California!!

[barefoot]

I do not have return line & just run a small diameter plastic hose from the tank vent fitting to under the front. Do not have fuel smell.

[Shivers]

I have heard both sides. Some say leave it even with carbs, that it will keep the fuel smell out of the cabin. I have carbs and no system and I have never had a problem. But if it is was there I’d use it this time. I also used only one line for fuel. But this time I’m going to use the second line for a return line off the carbs. It says you live in Florida, that would be a few blocks east of California.

[wonkipop]

I have a 72 1.7L with twin carbs, when moving the fuel pump to the front I noticed the return fuel pipe had been terminated presumably because it is no longer required. Question do I need the venting system, expansion tank, carbon filter and all the pipework, morden cars don't have this? I live in France by the way not California!!

modern cars do have it.
even europeans! have had it since at least the mid 90s if not slightly earlier.
i have a renault clio RS here in aus.
the whole kit and caboodle is on it, carbon cannister and all.
and typically french. the vapor line runs dangerously close to the crank pulley timing belt and is held on by plastic clips of typical french quality. these have since been replaced by me using usa quality know how - zip ties. (IMG:style_emoticons/default/beer.gif) less dangerous. engine less likely to detonate due to timing belt destruction.


attached is how its done on 914s for the rest of the world that did not have carbon canisters back then in the jurassic era (half a century ago.

dunno where you get the little T piece connector that lets you run the expansion tank vent hose into the plastic filler overflow but...... you would have to find something suitable. i'd say the original part is well and truly NLA being europe only.
alternatively find a way to feed the expansion tank hose (very small diameter) down to underside of car in steering rack area. helps keep any fumes out of the front luggage compartment area.








-----
not so relevant to EFI engines converted to carbs.
but.
1.8 euro was a factory twin carb.
fuel pump was mechanical. same as twin carb buses.
on underside of engine near flywheel.
no return line. think it was only at 3 psi same as most carbed VWs of the era.

[Petepat]

I have a 72 1.7L with twin carbs, when moving the fuel pump to the front I noticed the return fuel pipe had been terminated presumably because it is no longer required. Question do I need the venting system, expansion tank, carbon filter and all the pipework, morden cars don't have this? I live in France by the way not California!!

modern cars do have it.
even europeans! have had it since at least the mid 90s if not slightly earlier.
i have a renault clio RS here in aus.
the whole kit and caboodle is on it, carbon cannister and all.
and typically french. the vapor line runs dangerously close to the crank pulley timing belt and is held on by plastic clips of typical french quality. these have since been replaced by me using usa quality know how - zip ties. (IMG:style_emoticons/default/beer.gif) less dangerous. engine less likely to detonate due to timing belt destruction.


attached is how its done on 914s for the rest of the world that did not have carbon canisters back then in the jurassic era (half a century ago.

dunno where you get the little T piece connector that lets you run the expansion tank vent hose into the plastic filler overflow but...... you would have to find something suitable. i'd say the original part is well and truly NLA being europe only.
alternatively find a way to feed the expansion tank hose (very small diameter) down to underside of car in steering rack area. helps keep any fumes out of the front luggage compartment area.








-----
not so relevant to EFI engines converted to carbs.
but.
1.8 euro was a factory twin carb.
fuel pump was mechanical. same as twin carb buses.
on underside of engine near flywheel.
no return line. think it was only at 3 psi same as most carbed VWs of the era.

Thanks guys that was really helpful.

[rfinegan]

If I am reading this venting right.....

1) You do not need to use the return line if your fuel pump has dead head /bypass in the fuel pump and regulate to 3-3.5 PSI
2) Gas tank vent. Yes the tank needs have a vent. NO, it does not “have" to have a Charcoal vapor system and such, but pressurized vapors must be able to escape the tank on hot days and outside air must come in for the gas to flow

over simplified ..but I hope this helps

[mlindner]

+1 rfinegan. Carbs with only one line, small tube from tank vented to bottom of car. No gas smells driving or when garaged. Mark

[ClayPerrine]

I will say this.. I think the charcoal canister should be installed. It is a minimal weight, does not rob any horsepower, keeps the gas smell out of the car, and it helps the environment.

Seems like a win-win no brainer to me.

[SirAndy]

I will say this.. I think the charcoal canister should be installed. It is a minimal weight, does not rob any horsepower, keeps the gas smell out of the car, and it helps the environment.

Seems like a win-win no brainer to me.

(IMG:style_emoticons/default/agree.gif)

[rfinegan]

I think that is a fair amount of time and cost if its already all taken out, and you have to buy all the missing replacement components
...but that’s an assumption on the cars current state

[ClayPerrine]

I think that is a fair amount of time and cost if its already all taken out, and you have to buy all the missing replacement components
...but that’s an assumption on the cars current state

The parts for the canister system were installed on so many cars that have been parted out that, from what I have seen, people practically give them away.

And it is worth the time in the long run.

[rfinegan]

Since most of the old charcoal canisters are in need of updating...
I may as well put this here:
https://www.youtube.com/watch?v=6C06XJgLhIc


I did my 75 canister and was EZ and made a bid difference in fuel smells diminished

[wonkipop]

I will say this.. I think the charcoal canister should be installed. It is a minimal weight, does not rob any horsepower, keeps the gas smell out of the car, and it helps the environment.

Seems like a win-win no brainer to me.

(IMG:style_emoticons/default/agree.gif)

100% with you two.

the VW evap system of that era is a great example of german simplicity (not their usual over engineering (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) ). using a bleed off the air cooling fan to oxygenate the charcoal additional to engine intake draw and release hydrocarbons was a bonus above and beyond other manufacturers who only used intake draw.

and.......if you really want to get esoteric the 914 got the "proper" set up for the can in 1974 beginning with the cars that had the can in the engine bay. the plumbing on the hoses is reversed. its all in the L jet thread in originality section of website. they did change it. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/beerchug.gif)
confirmed by the evap system warranties and schematics in those. (to settle discussion over how the hoses are connected). there is an early set up and a later set up.

the earlier system with the can in the front trunk is the porsche design layout of hoses and was tailored specifically for the 914/6 and its carb vapor load at hot shut down. all VWs had it plumbed up the opposite way - tailored for EFI which has little vapor load at hot shut down from the engine itself. they finally changed 914s over in 74 to match all VW models when they were no longer offering any carb models and the 6 had gone out of production. that esoteric detail may be of interest to those with a 4 running carbs and who have retained the cans. the hose set up is probably better following the early version of connecting the can).

i suspect it works either way but VW must have had a very good reason for doing the opposite way to porsche. porsche themselves switched over to the VW method once their model range only had fuel injection in the USA.

vapor loads from open vented fuel systems were estimated to account for 50% of hydrocarbon emissions when the systems were introduced in 1969. with one simple move the EPA knocked out half the emission problems of cars with no detriment to engine performance. zero effect. one of those great ideas that took the rest of the world a while to follow but now its 100% of all cars made.

i think australia might have been the second country to do it shortly after the USA.
its either australia or japan.