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View Full Version : Fuel System: Question on Avanti gas tanks, the vent tube.



grobb284
07-28-2013, 07:49 AM
I am having a problem on my 1982 Avanti gas tank, installed in my 1963 Avanti.

I have the hose going up into the passenger sail panel, just like the 1963, and venting over the axle. This hose is attached to what is marked overflow in the picture.

I have my 5/16 return line splitting into two 5/16 lines, going to both the top drain and return line. just like a 1982 Avanti.

My problem is that even with only 4 gallons of gas in the tank, fuel is going up into hose from the tube marked overflow. The tank is then somewhat sealed, and then develops some pressure.

My question is: The tube ( marked overflow) that acts as a vent in a 1963 Avanti (and is short), is it longer (?) in a 1982 Avanti, and goes near the bottom of the tank for the EPA for a sealed tank system for emissions? Is that why it can't vent properly?

Curious if anyone else has experienced this, or specifically knows what is going on here.

sweetolbob
07-28-2013, 08:09 AM
Gene

IIRC, the two 1/4 pipe fittings on the top of the tank are for an elaborate tubing system that provides a vent that won't allow sloshing gasoline to enter due to the matrix above the tank.

I am piping my return line back in through one of those by drilling out a 1/4" compression to 1/4" pipe fitting to allow a dip tube to be run through the fitting down into the tank as you are also.

To answer your question, your return line that you are using as a vent, goes to near the bottom of the tank as you suspect.

Here's the return line install on my EFI setup in the 83. I just capped off the old return line.

http://i258.photobucket.com/albums/hh263/sweetolbob/P1010574.jpg (http://s258.photobucket.com/user/sweetolbob/media/P1010574.jpg.html)

Bob

grobb284
07-28-2013, 11:28 AM
Bob, did you receive the Ebay part I sent you?

Thanks for verifying that the tube marked "overflow" is indeed near the bottom of the tank. That explains a lot.

Are you using a vented cap then, since you have plugged the return near the fill tube, and the overflow as well?

I'm thinking that is a solution to what I'm seeing.


I have remade the dual tube system that you mentioned as being installed on the later Avanti II for my return lines (going to the 1/4 female pipe fittings soldered in the corners of the tank). I'm thinking that is what it was for, with the charcoal canister system going to what is called the overflow tube. Do I have it backwards?


Thanks for responding.

StudeRich
07-28-2013, 05:16 PM
Man that looks like one complicated mess! :ohmy: I am so glad Studebaker Avantis are simple, not like an Avanti II. And I sure would not change that.

sweetolbob
07-28-2013, 05:49 PM
Bob, did you receive the Ebay part I sent you?

Thanks for verifying that the tube marked "overflow" is indeed near the bottom of the tank. That explains a lot.

Are you using a vented cap then, since you have plugged the return near the fill tube, and the overflow as well?

I'm thinking that is a solution to what I'm seeing.


I have remade the dual tube system that you mentioned as being installed on the later Avanti II for my return lines (going to the 1/4 female pipe fittings soldered in the corners of the tank). I'm thinking that is what it was for, with the charcoal canister system going to what is called the overflow tube. Do I have it backwards?


Thanks for responding.

Gene

Yes it got here in fine shape, thx.

I am using a vented cap on the 83, on the 74 I'm not sure if I'll use one or vent through a loop over the other 1/4" opening. It sounds like that's not an option for you as you said you were using both for return lines.

IIRC the original plumbing was the maze of tubing going to both 1/4" fittings you have labeled return and top drain and that whole system venting to the charcoal canister. The original tube you labeled overflow is the return line from the carb.

Avanti, Bob

sweetolbob
07-28-2013, 05:53 PM
Man that looks like one complicated mess! :ohmy: I am so glad Studebaker Avantis are simple, not like an Avanti II. And I sure would not change that.

Right you are Rich, although it's got nothing to do with original vs II's but just the progression from the "good ol days" to the emissions era. Certainly not an era I remember fondly for automotive excellence.:(

Bob

mbstude
07-28-2013, 07:52 PM
Here are some pics from a stock 1982 Avanti I worked on recently. I was the first person since 1982 to remove the rear seat. Here are some before pics of that complicated mess. Bob's method of removing the vent piping and simply using a vented cap sounds like a good one. Wish I had've thought of that when I replaced all those rubber hose pieces.

http://i1315.photobucket.com/albums/t590/56president/1_zpsd23c5890.jpg

http://i1315.photobucket.com/albums/t590/56president/3_zpsc752754b.jpg

http://i1315.photobucket.com/albums/t590/56president/4_zpsab1a0425.jpg