s14 factory fuel tank ventilation - the 3rd hard line - Page 2 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

cured13 · 09-01-2013, 11:30 AM

to make it clear,
after cutting off the hard lne and Charcoal Canister on s13
the Fuel Filller Cap should be upgraded to the s14 one?

I just don't want to burn in flames when my car rolls over and fuel leaks through that cap also don't want to kill the fuel pump fighting to pump fuel in normal operation.

Mikester · 09-01-2013, 12:04 PM

Quote:

Originally Posted by cured13

to make it clear,
after cutting off the hard lne and Charcoal Canister on s13
the Fuel Filller Cap should be upgraded to the s14 one?

I just don't want to burn in flames when my car rolls over and fuel leaks through that cap also don't want to kill the fuel pump fighting to pump fuel in normal operation.

http://zilvia.net/f/s-chassis/503574...ap-system.html

I got a good laugh out of re-reading that thread- Killer2001 is a very smart, passionate guy haha!

An S14 cap will be good once the rest of the system is deleted. However, with the top (original evap) line vented to atmosphere, it is not completely necessary. The key is that the tank needs to 'breathe' so as not to overpressurize with fumes or implode due to excessive back-pressure.

You had mentioned 'burning to death in the event of a rollover... Not very likely due to the location of the vent. Also, without a roll cage, fuel leaking from the top of the tank during rollover would probably be the least of your immediate worries

I still have not gotten an S14 cap... but my S13 is not a daily driver & spends much of its life in the garage under a cover. An S14 cap would be MUCH more practical if I had the upper evap port completely blocked off.

jr_ss · 09-01-2013, 06:59 PM

The S14 tank has a "breather" tube that goes back up to the filler neck.

cured13 · 09-01-2013, 07:37 PM

Roll cage is on my list (somewhere at the end of it)
but getting that Charcoal Can and lines off my car is at the top of it.

What other 2-way cap (other than s14) can be used on s13,
anybody tried other Nissans caps?

Mikester · 09-02-2013, 02:43 PM

Quote:

Originally Posted by cured13

Roll cage is on my list (somewhere at the end of it)
but getting that Charcoal Can and lines off my car is at the top of it.

What other 2-way cap (other than s14) can be used on s13,
anybody tried other Nissans caps?

You can awlays Google the part number and see...

However- Why re-invent the wheel? S14 cap does the trick... and plugs & plays... and is probably the very same part # across a zillion other 1995+ Nissan models for that very reason.

KiLLeR2001 · 09-02-2013, 06:54 PM

Personally, I would keep both the gas cap (S14) and fuel check valve. If you have an S13 cap, upgrading to the S14 cap should be a given. Any aftermarket gas cap you buy for a 240sx is going to be a two-way. It would be wise to buy OEM however, it has the exact specifications needed for our cars. To me it seems that if you only have the cap doing all the work, it will need to be replaced more often. And I'm not even sure the gas cap alone can keep up with the amount of pressure that needs to be released... I installed an S14 cap on my two-tone and when I go to remove the cap I get a little release of pressure (which seems normal). When I had the S13 cap it was A LOT more air rushing out. This leads me to believe that my fuel check valve may need to be replaced. I am going to replace it soon and will be interested to know if the amount of pressure at the cap changes. I will report back.

Mikester · 09-02-2013, 08:17 PM

^^Will be interesting to see.

BTW, the infamous S13 'WHOOSH' is usually air rushing in, not out

KiLLeR2001 · 09-03-2013, 01:49 AM

Quote:

Originally Posted by Mikester

^^Will be interesting to see.

BTW, the infamous S13 'WHOOSH' is usually air rushing in, not out

I find that hard to believe because not only do I feel air pushing onto and around my hand, the smell of fuel is directed outwards. If you are experiencing vacuum when you remove your gas cap then you need to replace the gas cap immediately because it is not working properly. The gas caps' main job is to suck in air from outside when fuel is removed from the tank. A fuel tank that is completely blocked off could either implode (too much vacuum) or explode (too much pressure). Although I would imagine it would take extreme measures for either outcome to happen, the fuel pump would more than likely stop functioning before that.

Mikester · 09-03-2013, 05:58 AM

Quote:

Originally Posted by KiLLeR2001

I find that hard to believe because not only do I feel air pushing onto and around my hand, the smell of fuel is directed outwards. If you are experiencing vacuum when you remove your gas cap then you need to replace the gas cap immediately because it is not working properly. The gas caps' main job is to suck in air from outside when fuel is removed from the tank. A fuel tank that is completely blocked off could either implode (too much vacuum) or explode (too much pressure). Although I would imagine it would take extreme measures for either outcome to happen, the fuel pump would more than likely stop functioning before that.

Lol tank implosion is a definite possibility if not vented in some way shape or form- seen it happen to a high-hp car w the tank evap completely blocked off. However, with an elec pump in the tank; negative pressure is not a bad thing in moderation. Keeps fumes at bay. Not saying there would NEVER be a rush of air out due to heat, expansion & evaporation; but when regularly driven (S13 w OEM cap), the majority of air pressure will be negative due to pump suction. Not talking a huge amount, but enough just to equalize the pressure.

Mister.E · 03-06-2014, 06:50 PM

Sorry to revive an older thread, but i needed to get some clarification.

Im planning on buying this Gate's cap to replace my old ass OEM S14 cap: http://www.frsport.com/Gates-31615-P...L_p_29261.html

With a properly operating cap, are people with S14's just blocking off the vent line completely? If not, then what are you doing? i dont want to attach a line and just leave it open to the air, it gets hot as hell here in vegas in the summer and i fear i would get a ton of fuel evaporating and just be wasting gas.

09-01-2013, 06:59 PM	#33
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,052 Trader Rating: (34) Feedback Score: 34 reviews	The S14 tank has a "breather" tube that goes back up to the filler neck. __________________ My SR20VET

09-02-2013, 06:54 PM	#36
KiLLeR2001 Post Whore! Join Date: Jun 2007 Location: オーランドフロリダ Posts: 7,955 Trader Rating: (46) Feedback Score: 46 reviews	Personally, I would keep both the gas cap (S14) and fuel check valve. If you have an S13 cap, upgrading to the S14 cap should be a given. Any aftermarket gas cap you buy for a 240sx is going to be a two-way. It would be wise to buy OEM however, it has the exact specifications needed for our cars. To me it seems that if you only have the cap doing all the work, it will need to be replaced more often. And I'm not even sure the gas cap alone can keep up with the amount of pressure that needs to be released... I installed an S14 cap on my two-tone and when I go to remove the cap I get a little release of pressure (which seems normal). When I had the S13 cap it was A LOT more air rushing out. This leads me to believe that my fuel check valve may need to be replaced. I am going to replace it soon and will be interested to know if the amount of pressure at the cap changes. I will report back. __________________

09-02-2013, 08:17 PM	#37
Mikester Nissanaholic! Join Date: Jun 2007 Location: Kathleen, GA Age: 50 Posts: 1,938 Trader Rating: (0) Feedback Score: 0 reviews	^^Will be interesting to see. BTW, the infamous S13 'WHOOSH' is usually air rushing in, not out __________________

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09-01-2013, 11:30 AM	#31
cured13 Zilvia Addict Join Date: Apr 2008 Location: Almostthere Posts: 690 Trader Rating: (11) Feedback Score: 11 reviews	to make it clear, after cutting off the hard lne and Charcoal Canister on s13 the Fuel Filller Cap should be upgraded to the s14 one? I just don't want to burn in flames when my car rolls over and fuel leaks through that cap also don't want to kill the fuel pump fighting to pump fuel in normal operation.

09-01-2013, 07:37 PM	#34
cured13 Zilvia Addict Join Date: Apr 2008 Location: Almostthere Posts: 690 Trader Rating: (11) Feedback Score: 11 reviews	Roll cage is on my list (somewhere at the end of it) but getting that Charcoal Can and lines off my car is at the top of it. What other 2-way cap (other than s14) can be used on s13, anybody tried other Nissans caps?

03-06-2014, 06:50 PM	#40
Mister.E Post Whore! Join Date: Oct 2007 Location: Las Vegas Age: 36 Posts: 4,590 Trader Rating: (53) Feedback Score: 53 reviews	Sorry to revive an older thread, but i needed to get some clarification. Im planning on buying this Gate's cap to replace my old ass OEM S14 cap: http://www.frsport.com/Gates-31615-P...L_p_29261.html With a properly operating cap, are people with S14's just blocking off the vent line completely? If not, then what are you doing? i dont want to attach a line and just leave it open to the air, it gets hot as hell here in vegas in the summer and i fear i would get a ton of fuel evaporating and just be wasting gas.