Discussion Forum - Northstar Chevelle Club

Bowtieman427 · Active Member

72 Chevelle fuel coming out of cap at track Fuel shoshing around.

Lost in the 60s · President

Get a NEW NON-VENTED cap and try that first. Your old, vented cap may not be sealing any longer. I may a rear sump tank for a Chevelle that may solve the starvation issue too. I'll have to see if it's still around.

Chris R · 2K+ Club

I would try the cap first too. I had a problem like that on the street many years ago. Everything was stock configuration so I just replaced the cap.

bowtie · Secretary

I have an extra cap you can try if you want. Lemme know and I'll bring it to Car Craft.

Bowtieman427 · Active Member

Thanks Bryan. I may be at CC do not know yet Leah is working and see how it goes. Is there a specific cap I need to get. Mitch mentioned "Non-Vented"
1) If the cap I have is Vented (I bet it is) if I get "NON-Vented" would I have a new set of issues ? Do all the vented styles leak I would think it would be a one way design.
2) Bryan thanks for the offer I may or may not be up for CC.

Back in Black · Active Member

Non-vented cap did not work for me. Maybe I got a bad one. Got black flagged at Brainerd for fuel coming out of the tank. Doesn't help that BIR is mostly right handers and the filler neck is on the left side. For a quick fix, I found a plastic bag and cut a few pieces big enough to cover the cap and neck and zip tied them down. Didn't totally eliminate fuel coming out but cut it down at least 90% I'd say and I was able to continue. Never did find a permanent solution but my next idea was to find a filler neck with the unleaded restrictor in it and graft that on the tank somehow.

John D · 2K+ Club

Clarification: I have available for sale ($50) a rear-fill (behind the license plate) plastic fuel tank, out of a '96 Roadmaster/Impala Sedan.

It does not include the hanging/mount straps, but DOES include a non-functional fuel pump & sender assembly (easily ordered & replaced, it is a standard replacement part).

(edit)

Caviat Emptor... the tank(s) of this vintage just have a ribbed bung molded in for the fill port. You connect your OEM steel fill pipe to them via a rubber hose section just like old-school. There IS a an "anti-backslosh-pingpong ball in a tube/siphon hose/gas-stealer preventer" insert in the tank at this point.

Enganeer · Mega Poster

You could always try and make a removeable foam buffer at the fill tube. Stuff it in when you need and then pull it out when done.

http://www.speedwaymotors.com/Safety-Racing-Fuel-Cell-Safety-Foam,884.html

Back in Black · Active Member

Enganeer wrote:
You could always try and make a removeable foam buffer at the fill tube. Stuff it in when you need and then pull it out when done.

http://www.speedwaymotors.com/Safety-Racing-Fuel-Cell-Safety-Foam,884.html

I think we have a winner!

Tim H · Mega Poster

We use the foam in our fuel cell for our race car. It does well when the tank is stuffed full. I would be concerned if it was only used in the filler neck as the rest of the gas would still have the momentum of going backwards. It may help some but it is very porous and I think you will still have an issue. It you filled the tank with it that may work bertter but then your sending unit would not operate.

I once saw a tube that inserts into the filler neck that is sealed on the end so that gas does not come up the neck. It was attahed to it's own gas cap. It was made for racing. The tube was flexible.

dashboard · 2K+ Club

What is the history of your tank, is it origional?

John D · 2K+ Club

I have a '96 B-body (Roadie/Impala) rear fill tank. $50

dashboard · 2K+ Club

John D wrote:
I have a '96 B-body (Roadie/Impala) rear fill tank. $50

John, is that side fill?

Tony Hoffer · Moderator

When I was still running the stock tank the switch to the non vented cap worked for me.. The switch to the Ricks tank solved most of the other issues you have mentioned..

Lost in the 60s · President

My suggestion of a NON-VENTED cap was for track use only. You would need to open it after every run to relieve the vacuum but the fuel would stay in. I see there are other suggestions that may be easier to use instead.

seagrams72 · Active Member

I thought 72' (like your car and mine Jim) had a non-vented cap b/c it had the EEC where it was vented in the back of the tank? EEC meaning the three nipples coming out of the tank that lead to the deal behind the rear seat that leads to the charcoal canister in the engine compartment. I assume this system has been removed on your car.

I thought 70' and older had the vented cap. I could be mistaken though.

Jim if you want to see a sumped tank I will be at Car Craft and have one in my car. Works great under throttle, but under hard braking sometimes you can hear the fuel pump starve a bit.

Bowtieman427 · Active Member

dashboard wrote:
What is the history of your tank, is it origional?

It is original.

Mitch I think I will try your idea first. It seems the cheapest.

I will research more on the F body tank I believe it has baffles to keep EFI pump fed. Can I use the stock FP that is designed for FI ?

I like the cell idea as it may be safer.

Lost in the 60s · President

John D wrote:
Caviat Emptor... the tank(s) of this vintage just have a ribbed bung molded in for the fill port. You connect your OEM steel fill pipe to them via a rubber hose section just like old-school. There IS an "anti-backslosh-pingpong ball in a tube/siphon hose/gas-stealer preventer" insert in the tank at this point.
That's a "rollover" valve intended to prevent fuel from leaking when the car is upside down. It would also prevent fuel from sloshing out the neck under acceleration...

Lost in the 60s · President

Bowtieman427 wrote:
dashboard wrote:
What is the history of your tank, is it origional?
It is original.
Mitch I think I will try your idea first. It seems the cheapest.
I will research more on the F body tank I believe it has baffles to keep EFI pump fed. Can I use the stock FP that is designed for FI ?
I like the cell idea as it may be safer.
That pump pushes a lot more pressure than a carb needs and would be severely choked by a pressure regulator. I would recommend retaining the fuel pump/regulator you have now. I believe John's tank will fit under an a body much better than the f body tank, as it is flatter, like original.

4-door Chevelle · Super Poster

I run a stock tank in my 72 with a stock cap and have never had any of the issues you speak of. In fact, my other 72 didn't have any issues either. I run at least a half tank when I race for traction and if I get lucky enough to go a few rounds.

Derek69SS · Founding Member

Jim, I have a 91-96 Caprice/Impala tank at my place you can have for free...

Bowtieman427 · Active Member

Derek, THAMK YOU for the offer check PM. It may be a very viable option and may solve my issue. I have been looking at cells too. The sumped option seems pretty good but welders want to use a new tank and it should be coated when completed it can rust where the wleds are.

I did NOTget flagged at Cedar Falls but only went hard 2x. Darren I have no idea why you have not had an issue with this. I got talked to 2x at RF. I also notice that below 1/2 tank with my setup the FP is all over because of Sloshing around. My Fuel delivery is not stock with electric pump and I am having an issue. I think others have had issue also.

Seen a post on another forum " Another question for those who have completed this swap and driven around in the car afterwards: Has anyone checked to see if this tank does anything to alleviate the trademark "shoots gas from the gas cap under hard acceleration from a dead stop" issue that is common for 68-72 A-body cars? Im no environmentalist but I paid for that gas and I want it going towards moving the car forward not cleaning the pavement around town!

if you keep the Caprice screw in cap and keep the baffle in the filler neck, then it shouldn't be a problem. if you keep the Caprice screw in cap and keep the baffle in the filler neck, then it shouldn't be a problem.

Exactly. I use the caprice tank filler with the non vented cap, and I also run the complete EVAP system as well. Not necessary but I try to do factory style installs. "

Looks like the stock baffling with screwin cap is key to keep gas in the tank on launches. using the 91-96 Impala tanks and many used the Impala starps for install.

Anyone try this install ? Any issues findings ?

-- Edited by Bowtieman427 on Saturday 11th of August 2012 01:11:57 AM