240Z fuel pipe routing?

[hatsu]

Today i filled my 240z up with fuel for a dry sunny but cold day drive. The 1st time i have fully filled the car with fuel.
I noticed a smell of fuel but i had just filled up so thought nothing of it. When i parked up i noticed some liquid coming out of the front drivers side (its a uk spec car), sure enough it was fuel.
Now, i have 2 metal pipes coming from the tank, one obviously is the fuel supply that was nice and dry and secure and feeding the carbs, via a filter.
The other one was just open to atmosphere, and i noticed a rubber pipe had a bolt shoved into it to blank it off, this comes from the carbs.
I am assuming this blanked off rubber pipe should fit the open pipe, but why would someone do that? I have only had the car for a month or so, im not guilty of the strange mod.
I can guess its either a fuel return pipe or a breather pipe from the tank.
Anyway i have connected it up and it runs ok so its left me puzzled.
Anyone got any suggestions?​

 

[jonbills]

sounds like the return pipe.
perhaps it leaks and the owner blocked it off rather than repair it?

 

[hatsu]

Ok that makes sense. Does it matter if its blocked off rather than connected to the tank pipes?
Also could this have possibly been why it is a nightmare to start from cold i wonder?
I will go and start it up tomoro and see if the return line is leaking anywhere.

 

[Rob Gaskin]

Hatsu, try to keep it connected if poss. Run the car whilst stationary and check for leaks. The pipes on my old 240Z were corroded where they go through a rubber block above the diff. I noticed them before it developed a leak.

Starting from cold. Do you mean just starting from cold anytime or after a break of a couple of weeks. The mechanical fuel pump can be a problem when the car hasn't run for a while, it doesn't 'prime' very well. Try using 'Easy-start' or similar to get the motor started and running which will then get the pump 'primed'.

 

[hatsu]

Hatsu, try to keep it connected if poss. Run the car whilst stationary and check for leaks. The pipes on my old 240Z were corroded where they go through a rubber block above the diff. I noticed them before it developed a leak.

Starting from cold. Do you mean just starting from cold anytime or after a break of a couple of weeks. The mechanical fuel pump can be a problem when the car hasn't run for a while, it doesn't 'prime' very well. Try using 'Easy-start' or similar to get the motor started and running which will then get the pump 'primed'.

Starting problems are every time when its cold be it a week or the next day. The choke lever moves the arm on the carbs, but doesnt seem to have any effect. I have to use a combination of lots of cranking,patience and throttle to get it started.

I will check for leaks once i have managed to get it started tomorrow.

 

[nissanabuser]

If its carbs there will be no return to the tank, only injection cars have that.
Carbs are designed to stop the flow of fuel once the bowl is full of fuel so you probably have a sticking or worth fuel needle that cuts the flow of fuel off.
Re the other pipe to the tank, does it defo go into the tank? Can you smell fuel from this pipe?

 

[Mr.F]

All S30 models with carbs have a fuel return pipe with a restrictor in the line. Helps with the fuel vaporisation problem that Zs suffer from.

 

[MaximG]

If its carbs there will be no return to the tank, only injection cars have that.
Re the other pipe to the tank, does it defo go into the tank? Can you smell fuel from this pipe?

No offence intended but please refrain from making comments about things you obviously have no idea about. There are plenty of enlightened Z Cub members on this forum that are able to help hatsu with accurate information.

 

[hatsu]

Hatsu, try to keep it connected if poss. Run the car whilst stationary and check for leaks. The pipes on my old 240Z were corroded where they go through a rubber block above the diff. I noticed them before it developed a leak.

Starting from cold. Do you mean just starting from cold anytime or after a break of a couple of weeks. The mechanical fuel pump can be a problem when the car hasn't run for a while, it doesn't 'prime' very well. Try using 'Easy-start' or similar to get the motor started and running which will then get the pump 'primed'.

I will check the pipes are all leak free.

My car doesnt have a mechanical fuel pump, its got a blanking plate over the hole, only uses an electric fuel pump.

 

[morbias]

I think MaximG was only referring to the fact there is a fuel return on cars with carbs, there is a restrictor on the end of the fuel rail which then runs to the fuel tank (or maybe I am mistaken?). It wasn't a general attack on your car knowledge, so let's not get all excited!

 

[Rob Gaskin]

Well I for one won't be missing input from Nissan Abuser (Z Owner Abuser more like).

I try to give help and then he posts telling me that the fuel return system on my two 240Zs never existed.

Mike B puts him right and then he verbally abuses us and our cars.

 

[SKiddell]

Well hush my mouth, didn't realise these stupid ******* Z cars worked in no other way from a usual car

All the more reason to keep your mouth shut until you have had at least 30 seconds worth of experiance working on them

????? Many carb'd based cars used a return line, its sound practice

Self proclaimed experts eh!!!

 

[RIDDLER]

Well I for one won't be missing input from Nissan Abuser (Z Owner Abuser more like).

I try to give help and then he posts telling me that the fuel return system on my two 240Zs never existed.

Mike B puts him right and then he verbally abuses us and our cars.

Agreed. If he has so little respect for Z cars (not a proper sports car etc) then why is he on the forum? Let him go abuse something else.

 

[Paul Henley]

Fuel Line Type/Size

Hi All

Jumping on the back of this thread (a good informative thread) I'm about to replace the brake and fuel lines on my 240z shell, but it's 15 years since I stripped it, so the memory banks are short on some detail Can someone please advise the type and size of the fuel pipes running from the tank to the engine bay, better still a link to an internet site with picture/description would be perfect, I'm looking for something as original as possible. Many thanks In advance - Paul

 

[morbias]

I looked up an order for fuel hoses I made last year, I ordered two separate lengths of:

5/16"
1/4"

I can't remember what sizes fit on which part of the fuel system now, maybe the smaller bore was for the return line?

Or maybe it's all 5/16" and the 1/4" is from the fuel rail to the carbs.

 

[MaximG]

Large bore flow, small bore return.

 

[Paul Henley]

Excellent, thanks for the info, is it made of the same stuff as the brake Pipes? (threw the originals out years ago


Thanks again

Paul

 

[MaximG]

Copper/nickel

 

[Mr.F]

Large bore flow, small bore return.

240Z only; 260Z both same (larger) diameter.

 

[Paul Henley]

I actually found my original pipes and they appear to be, brake and fuel return 3/16" and Fuel Feed 5/16".
One thing that does puzzle me is why does it appear that the US Z's have 4 pipes flowing down the length of the tunnel as opposed to our 3?
Paul