ZCar Forum banner

Status
Not open for further replies.
1 - 16 of 16 Posts

·
Registered
Joined
·
2,405 Posts
Discussion Starter #1
Four years ago I removed the vapor canister on my 81 280zxt in order to route my intercooler piping. Before removing it, I researched on Zcar and Hybridz the impact of leaving the tank unvented. The research results were 50/50, some saying that leaving the tank unvented would not cause any issues while others suggested adding a vent or tucking a small vapor canister from a different model car in the wheel well (I should have listened Tonyd!!).

I decided I would not initially vent the tank and would monitor the tank when filling, etc for odd behavior. My Z is driven at most 2k miles a year. During that time I only experienced one odd experience when the tank blew a 4 foot stream of gas onto the adjacent gas pump when I cracked open the filler cap. I might add my boost is set at 12 PSI and is fueled by a fuel pump from a Porsche 911 twin turbo.

Last fall, three years after having removed the vapor canister, my Z started experiencing fuel starvation issues. Whenever the gas level dropped below 3/4's the fuel pressure would fall off and it would run lean.

After a very frustrating period of investigation and head scratching, I finally realized what the issue was. When viewed from underneath, it appeared that my gas tank was crushed! Which was even more evident when I dropped it and saw the condition of the top of the tank.

It appears that after an unusually long day of spirited driving to and from Lime Rock Park on our club's annual Bob Sharp Lime Rock day last summer, the vacuum built up in the tank to a point that it permanently deformed the tank, forming an impressive crease in the metal. The heavy fuel pickup tube was bent to the point that the strainer was snorkeling above the fuel level at 3/4 tank. Needless to say, the replacement tank is going in soon and will be vented.





 

·
Registered
Joined
·
471 Posts
Wow
I was going to just relocate the carbon canister when I do the intercooler & swap, now I am convinced that is the way to go.
Thanks for posting that & the pictures, very informative!

The capacity of the tank must have dropped but would be hard to notice since you could not run below 3/4 before filling back up.
 

·
Registered
Joined
·
1,299 Posts
Visual evidence!

Maybe this will finally convince those otherwise that want to "delete all the useless smog stuff." Thanks for the post, and good luck. Hope you get back on the road soon!
 

·
Registered
Joined
·
2,405 Posts
Discussion Starter #4
I initially thought there was a pinhole leak in the fuel pickup tube that would suck air when the fuel level dropped below it. But then I couldn't pull the fuel sender out of the tank and couldn't figure out why!!
 

·
Registered
Joined
·
164 Posts
Phil280zxt Wrote:
-------------------------------------------------------
> I initially thought there was a pinhole leak in
> the fuel pickup tube that would suck air when the
> fuel level dropped below it. But then I couldn't
> pull the fuel sender out of the tank and couldn't
> figure out why!!

Knowing that PRETTY car of yours, it's hard to believe
that something that UGGGLLLY came out of it!!
 

·
Registered
Joined
·
820 Posts
My CC and all the smog crap on my car is gone, but I still HAVE a filtered vent line from the line that used to go to the CC from the tank.

Been like that for 7 months or so now.
 

·
Super Moderator
Joined
·
6,412 Posts
I have actually seen a gas tank even more crunched up then that from a guy running a non venting cap when his car called for a vented cap. His wife left the cap at the gas station and when she realized what she did she went to the parts store and they sold her the wrong type cap. He didn't know until it was sucked up to less than half its original size. She wasn't allowed to drive his baby anymore.
 

·
Registered
Joined
·
164 Posts
zxtoy Wrote:
-------------------------------------------------------
> I have actually seen a gas tank even more crunched
> up then that from a guy running a non venting cap
> when his car called for a vented cap. His wife
> left the cap at the gas station and when she
> realized what she did she went to the parts store
> and they sold her the wrong type cap. He didn't
> know until it was sucked up to less than half its
> original size. She wasn't allowed to drive his
> baby anymore.

That comes under the heading of cruel and unusual punishment.
But in that case I believe it was warranted.
FWIW, ~Rick~
 

·
Registered
Joined
·
2,405 Posts
Discussion Starter #12
Astro, no, stock gas cap. In the process of removing the vapor canister I plugged the vent line leading from the gas tank allowing vacuum to build up over extended driving periods. On short trips the tank must have been able to vent itself enough to avoid collapsing the tank. I drove the car a total of 5-6 hours on the Lime Rock outing and the tank was not able to equalize the pressure in a timely enough manner.
 

·
Registered
Joined
·
1,772 Posts
yea i had the same problem of the gas shooting out of the tank, cause i blocked off the vent line with a vacuum cap, so i took the cap off and put a breather filter on it, had it that way for 2 years now, no problems. As long as the pressure has somewhere to go, then you wont have an issue with deleting the carbon canister.
 

·
Super Moderator
Joined
·
41,005 Posts
Tony D... "the Prickass"

Sorry to see that Phil, that sucks...er...

With the EFI pumps this indeed can happen. The early Z mechanical pumps will suck the filler neck down flat in the 1/4 panel if the hoses have good integrity.

But what do I know, right?

You don't need a cannister, perse. It helps because it has valves in it to give proper pump inlet pressure to prevent cavitation when below 1/4 tank with hot gas... But a simple little K&N filter on the end of one of the vent lines run up into the 1/4 panel to make a suction break and keep it from puking out gas when the tank is full, or when the gas expands is really all you 'need'...

Curious, here I'm an overbearing oagre tagged with 'prickass' as a handle by malcontents who think I say stuff just to hear myself talk.

Yet at hybrid Z they tagged me 'wiki' which I thought initially had to do with my masturbatory tendencies...but apparently it's a compliment akin to calling someone 'Encyclopaedia Brown' back in the day... whooodathunkit?
 

·
Registered
Joined
·
2,405 Posts
Discussion Starter #15
Re: Tony D... "the Prickass"

No matter what site you post to Tony, you are the walking Z encyclopedia in my book!!
 

·
Registered
Joined
·
1,772 Posts
Re: Tony D... "the Prickass"

Phil280zxt Wrote:
-------------------------------------------------------
> No matter what site you post to Tony, you are the
> walking Z encyclopedia in my book!!


i agree 100%
 
1 - 16 of 16 Posts
Status
Not open for further replies.
Top