Hey guys, I did some research on the topic of venting your fuel tank and just wanted to run what I'm doing by everyone before I blow myself up.

This is in a 72 chevelle, see sig for swap details if interested.

I'm using the Tanks Inc. in tank fuel pump setup in the stock Chevelle fuel tank and am not sure if I'm venting the fuel tank correctly. The stock tank has three vent lines (kinda like this one from the sticky but on my tank there's one on each end and one in the middle)


that run up into the trunk area and I believe then run into one small line somehow (not sure how they merge up there) that runs to the front of the car to a charcoal cannister setup. Well, the cannister setup has been taken off the car some time ago and I need to vent the tank. The Tank's Inc setup has an additional port other than the ones for the sending and return fuel lines. Like this from the sticky (the one in the middle is the vent):

I ran rubber hose from this line to a check valve near the bumper then capped the three stock vent lines.

Is this going to be safe for venting the tank? Will I risk having fuel come out of the vent line if the tank is too full?

Give me your opinions please!

 

I am not sure that this will work for venting fuel vapors and flumes.. the check valve may allow air into the tank (and keep vapor lock from happening?) and not allow gas to escape, but will the check valve vent out the vapors and flumes (which is needed) ? and even if it does vent the flumes and vapor out.. you will smell them and that what the Charcoal canister job is there for, to handle and eliminate the vapor/flumes (or the LS1 purge valve setup).

You might not want to park the car in the garage if you smell the flumes/vapors inside.

What is that check valve from ?

The 3 stock vent lines runs up into the truck area to what is called a Liquid-vapor separator and then one line run up to the front where the charcoal canistor is. Vacum is used to pull the vapors (via the PCV valve and port on the Carb for a vacum source) up from the tank into the canistor.

Hope this help you...







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Yeah, I'm not sure either... The check valve is suppoed to flow in the direction to let air out of the tank, and now that you mention it, if everything else is capped off how is air going to get in the tank to diplace the fuel that is used?

The check valve is a gm part that is recommended in the Tanks Inc. instructions.

I'm thinking of reinstalling the charcoal cannister setup to use with the stock purge valve controlled by the computer...but will this work without the fuel tank pressure sensor? If not I guess I could figure out how to install this too...Man, and I thought I was about a week away from getting this thing fired up

 

I am just going to running the Canister for now... plugged the purge valve, simple but works.

 

Is a fully sealed tank required? Why would there be a vent in the fuel pump setups everyone uses if it was not?

The tank must absolutely replace pumped fuel with air, and, likewise, when fuel is coming in through the fille, you must absolutely provide a way for that air to escape or a) The pump will stop, b) You'll be wearing fuel or c) You're going to have lots of gas fumes flying at you as the air rushes back at you.

I ran a hose off to vent similar to what is above. If that is not correct, I guess I need to know too!

 

I read somewhere here on these forums that the stock LS1 purge assembly will work without the pressure switch in the tank if you remove the check/code for the pressure switch from the PCM through LS1 Edit or similar.

 

yeah.. wasn't sure if it was going to work, that is why I took the simple route.. remove, plug and Can it ! Charcoal Canister that is.

 

I was wanting to clean up the top of the intake on my ws6 and remove the vent system. Then i realized the car would have a gas vapor always around it, in the garage that wouldn't be good. I'm still debating.

If 350SS was to put a bulkhead fitting in the top of the tank and use maybe -6an or -8an braided line, coiled it around twice(to keep any fuel from splashing out) then ran it closer to the outside of the car and somehow secured the line. Would that be adequate enough to vent the tank for a) filling the tank. and b) the car running(i.e. useing fuel) ?
I used this method on a race car, but not street driving, and it was only a 10 gal. fuel cell..

 

I also have yet to decide what I am doing about this. Does anyone know a good donor vehicle for a small canister I can mount next to the tank? Could I possibly make my own out of a catch can or something, just fill it with charcoal from a fish filter?

Is it necessary to pull vacuum on the canister or could it just be left open? Maybe a hose w/ a small filter leaving it.

I don't think my car has ever had anything on it since it's been mine. Just open tubes on top of the tank. Probably not the best setup but I never noticed any problems.

It's a pain to search the auto parts stores online because you have to enter a vehicle first.

 

I have a feeling that I'm going to try to duplicate the factory setup as much as possible. Meaning I'll probably reconnect the three stock vent lines in the factory tank, find a charcoal cannister and mount it in the engine bay, and run a line to the intake somewhere. I'll probably plug the purge line in the Tank's inc. unit. Still, do I need to do anything to let air into the tank as fuel is consumed? I wouldn't think so since I'll be using the same setup as factory and they didn't have anything extra...

These aftermarket stainless EFI tanks seem to only have a sending and return line:


Although there might be something there in the middle between the fuel lines and the sending unit...does anyone have one of these tanks? How do they vent them? This is getting frustrating.

 

I read that a Mustang has a small Canister that is located near the rear of the car.. I have not see it myself.. anyone ?

 

I'd like to know that too. I have the Tanks Inc set up and ran a hose from that middle vent port over to the filler neck and just have it tied off over there with zip ties. I have had not problems with fuel odors that I have noticed. I still would like to have a charcola canister on the end of that vent line. My car spends most of it's time in a garage and under a cover.

Pat

 

The purge solenoid will work without the fuel pressure sensor. My car is set up that way. I just ran the vent line from the fuel tank to the charcoal canister and then the line from the charcoal canister to the purge valve. You don`t need to worry about venting the tank so that air can flow in since the charcoal canister will let air flow into or out of the tank.

 

Did you just use the stock cannister onthe El Camino?

 

Well I spent a little time looking through random ones. I think I need to go to the parts store and dig through them, but here is a start.

1995 Mustang GT - 49.99


1985 Carbureted Mustang GT - 41.88


1992 Honda Civic - 28.99


1990 MAZDA 626 DX - 71.99


1990 SUBARU LEGACY H4 - 43.99


1990 PONTIAC BONNEVILLE - 49.88


1990 PONTIAC GRAND PRIX - 39.48


1996 SUBARU IMPREZA L - 45.99


1996 MAZDA 626 ES - 54.99


1996 JEEP GRAND CHEROKEE V8 - 62.99

 

350SS
I also have the tanks inc. setup in my 78 trans am. Did you buy the gm breather that was listed in their directions? I bought that (it was around $13) and ran the vent hose towards the front of the car and placed it in the area where the crossflow muffler would go. You want the breather to be installed above the level of gas in the tank. I don't have the part number in front of me right now. The parts guy told me it was a breather GM used on auxillary fuel tanks in trucks. It allows air in and out of the tank. A small amount of pressure or vacuum has to build before it will open.

 

Yep, that's what I bought. But considering where it sits on the top of the tank, I'm worried that when the tank almost full, if there is no air where the purge fitting is, why wouldn't fuel get pushed out even if the valve is mounted high above the tank? I'm also obviously concerned about just releasing gasoline vapors around the car too... Those carbon cannisters look promising though.

 

Does anyone know the part number on this piece?

 

Yep, I used the factory El Camino charcoal canister.

 

For some reason I can't find my Tank's Inc. instructions. It's listed in there somewhere.