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Discussion Starter #1
Hi all
Ive got a Cali made 72 2 door and ive recently been experiencing a lot of pressure build up in my fuel tank. I am in the process of trying to work out how to vent my tank and Ive only just learnt there was a extensive EEC system on these vehicles of which NONE of the canisters / filters are in place any more.

So was wondering if the pipe in the attatched photo is part of the vent system for a front mounted charcoal canister and should it vent to release pressure from the fuel tank?

The pipe runs to the front left corner of the engine bay but ive got no pipes into the boot so I'm a bit confused.

Any assistance will be good till I can get it up on a hoist and work out the best way to vent the tank
Cheers
410738
410739
 

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EEC is a closed system that vents into the engine via the PCV in your period. Behind your rear seat will be a large vapor separator that has 3 - 4 lines going into it. One of those lines will be the one you have pictured. That line goes into the non-valved portion of the vented charcoal can (which appears missing here). The cans will usually have some type of text stamped into them indicating what goes where. Line port size will also vary.

Two other lines will going into the can at the restrictor valve: 1) ported vacuum off the carb. A "signal" line for the restrictor valve 2) another daisy chaining with the PCV valve to full manifold vacuum. There is sometimes also a fuel bowl vent line. Not sure about your year.

I would not attempt to resurrect this system without the Factory Chassis Manual at hand. Hooking up the lines wrong can cause some creative problems. There will likely also be other parts missing you are unaware of.

This is for '71 but helpful as well --
 

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Yes that connects to the charcoal canister. There are other aftermarket tank vents available that mount on the tank. I saw one on this site once put cant remember where. I have a fuel/vent line diagram if you need one.
 

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Discussion Starter #4
Edit...
I had a bit of a crawl under the car today and I think I do have an evaporative canister in the trunk?
410797
410800


So am I right in thinking this is an evaporative canister?
and
Any excess pressure in the tank should be venting to the canister in the boot and then released via the pipe that runs to the engine bay
(Charcoal canister)?
Or
Did the the charcoal canister require vaccum to draw pressure out of the fuel tank and evaporative canister in the trunk?
 

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Discussion Starter #5
Thanks SouthBay2s I'm pretty sure I get what you've explained. A service manual will have to be on the shopping list I think.
 

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Discussion Starter #6
Thanks J Mark
I would love a copy of that diagram if you have it handy. If not that's cool I'll just get a service manual and sort it.
 

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Discussion Starter #7
Update.
I found that a section of pipe between the A pillar area and the charcoal canister end was completely blocked with rust.
I have removed that section of line and im hoping that when I charge the remaining rear line to the tank with compressed air it will clear the line of debris.
Failing that I think I'm going to run a length of fuel hose to the engine bay and mount a catch can or breather.
 

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Discussion Starter #9
why not just get a vented gas cap
I was under the impression that vented caps were designed to only allow air into the tank and heard they can leak fuel under acceleration?

So was just going to try to keep the evaporative canister system in the trunk and run a new line for a breather/catchcan.
 

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My diagram is blurry crap but I have many partial drawings where I can piece it together for you. Give me a couple days. Like SouthBay2s said there are parts that may be missing and the first to go are the temp sensor and TCS.

I heard complaints about vented caps creating even worse fumes in the garage if that's where you park. Just what I heard, I have no experience to that.

I've searched for canisters several times and they were impossible to find but after another search thanks to your post I found one or more. Must of just started supplying them. I will get back to you with the complete diagram that you can understand.

 

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Discussion Starter #11
Thanks J Mark that would be awesome.

Today Ive determined that the vent line from the rear canister to the A Pillar area is also completely blocked so ive given up for this week and ill wait till the weekend to figure out what I'm going to do with it.

I like the look of the Repro vapour canister though thanks for the link.
 

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I put in the entire new stainless lines including the vent line. I just don't know what I'm going to do with it yet till I learn a little more. The vents you attach to the tank are mega expensive but may be the best option.
 

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The two manuals I posted will have diagrams of the system along with basic theory and diagnostics. Since shipping to Oceania is usually absurd, I can get some scans for you as well if needed.

When I worked at an auto parts store in the '90s the common GM cans were available, then they fell off the market. Looks like they are back which is great. If Standard is making them check with your local parts house first.

Do not mess with the vapor separator in the trunk. Those parts back there are unique and very hard to find. Fix the bad line and when you can re-plumb in the charcoal can. The main issue with the original systems is people messed with them.
 
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Discussion Starter #14
Update.
Thanks guys for your assistance its really appreciated. I have had a bit of a play today and I have hooked into the vapor separator in the trunk which is all working as it should.
Ive temporarily run some 3/8 fuel hose along the old vent line and vented it under the hood for now. (Probably all spring /summer)

When the funds are available ill replace the vent line with a stainless vent line and hook up a repro charcoal canister.

So far it hasn't gassed out my shed but its well ventilated so not too concerned about that ATM

I took it for a good drive and it could be the placebo effect but the engine seemed to run better with slightly better performance than before.

Cheers again
 

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Good deal (y) You may have had a minor vapor lock issue that was impacting fuel pressure. Or it was placebo... :) Either way it is a step forward.
 

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Hi Mark ............................................. maybe - - this ......................


and, Bunyip .......... this is what I would use ( I'm buying this , because , each time I remove my gas cap ................. I get a rush of air (exhausting) from my tank) .
AND, cheap enough ........ (unless you may have other - requirements) .
look at the lower part of their page . . . . . some "instructions for hooking up" .

just my 2cents .............. later , jim

ps =
I go with the - KISS , system .
 

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................ Bunyip ................ more - better - write - up about u'r ' charcoal canister ' , system .
(older post ........... but 'Ray_ McAvoy' ............ is still on this site) .



more info .......... another good "old" post .

jim
 
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