Venting fuel tank

[RichardERobbins]

Hey all. Apologies for what is likely a silly question but I'm still trying to sort out what was done to me my car before I got it. Many strange choices. I read various threads on this subject but failed to answer the simplest questions. 

 

There is a fuel line that runs from the top of the tank out and all the way to the front drivers side where it is clumsily plugged - and now leaking gas on occasion. 

 

My questions are two:

 

If the line is for venting fumes, why is it plugged? Should it be? 

 

Assuming  I need to address the situation - cause gas leaks are a bad idea - how/where should this line ideally be connected?

 

Should I just re-plug it more effectively or un-plug it and send it elsewhere? 

 

Thanks. 

[AustrianVespaGuy]

So, the line that is plugged is your fuel return line. My best guess is that when someone (likely a doofus) installed that electric fuel pump, they plumbed it straight to the carb (maybe with a pressure regulator and maybe not, so something else you should check), and then left it at that and never bothered with an overflow return line and just plugged the old one.  While the car should run OK this way, the added pressure will wear out the needle seat in the carb a lot faster.  My personal suggestion would be to redo this with a proper fuel pressure regulator and overflow return.

FYI, the orginal vent line should come from rubber filler neck and run up to a plastic tank above the right fender well.

-Carl

Edited April 9, 2017 by AustrianVespaGuy

[Son of Marty]

If you don't run a return line plug the old one right were it comes out of the tank.

[RichardERobbins]

Thank you. So as a short term fix I can just plug the line altogether? That seems to be what was done before, and would have stayed that way undetected by me, except that it started to leak. It seemed a really odd place for a fuel leak.

 

Any suggestions on finding some guidance on in stalling a proper fuel pressure regulator and overflow return?

 

[Mike Self]

The line you found up under the battery box is actually the vapor recovery return line.  Left connected back at the tank it will siphon gas out of the tank when it's full; that's why the PO plugged it.  

 

However, your gas tank still needs to be vented.  If it isn't, the pump will create a vacuum in the tank that will either become stronger than the pump can handle, or collapse the tank! 

 

If there isn't a very visible vent line leading from the rubber pipe that connects the gas filler to the tank, you can use the vapor recovery line nipple on the tank to run a vent hose out to the atmosphere.  This is what earlier 2002s had.  If you do this, simply make a loop in the line so at least part of the line is higher than the top of the tank, to prevent siphoning.  If you look under the trunk floor that covers the gas tank, you may well find a rubber plug towards the rear body panel.  That's were the gas tank vented on earlier US cars an on Euro cars contemporary with yours,.  You can lead the vent hose out through that plug.  

 

cheers

mike

[Son of Marty]

I'm sorry Mike but your a early round light car guy, that line returns bypassed liquid fuel to the tank, the air vent to the tank is the same as always. Richard you could plug the line with a new hose like before but if you plug it at the tank you eliminate any fuel in the line, you don't need a by pass fuel regulator at 2-3 psi they make for unsteady fuel pressure, this is not to say you don't need to regulate fuel pressure to 2 to 3 psi for a carb you just don't need to use a bypass