I'm doing a conversion that requires a return line for an electric fuel pump system.

The fuel breather line that normally goes to the carbon canister is perfect to use as a return line but before it goes into the tank in goes to a small tank hidden near the fuel filler neck in the side of the ute tray. I would like to just bypass this and hook it straight to the top of the tank but the filler neck also has a plastic tube on the side of it that appears to also go into the top of this small tank. If I disconnect the lines will I have problems with the tank breathing?

Thanks,
Daniel

Yes. If you use the fuel tank breather line as a return, how will the tank be vented?

The filler neck has two hoses Tee'd into it one large lower that feeds to the tank (guess its to allow air out of the tank while filling it) and a smaller one that allows "vapour" into the small hidden tank then back to the actual tank and to the breather that I want to use... So the way I see it is if I put the breather straight to the tank return then the small tank will be venting via the filler neck... downside is any vapour that collects as liquid will drain out of the small tank and onto the ground

What kind of problems can I aspect if I plug all the hoses and eliminate the return line?

> What kind of problems can I aspect if I plug all the hoses and eliminate the return line?

Datsun 1200 does not have a return line. If you eliminate the vent line:

* Fuel overflow
* Fume buildup
* Fuel leakage


Here is the late ute tank. Note that the Vent line is in front. The fuel supply line is not shown.

Its been 5 years since I used my breather line for a return line. I removed everything associated with the breather line. I haven't had any problems with over pressurizing the tank.
Up to you if you want to do it.
I'm eventually going to install a fuel cell tank.

datsa73, how is your tank vented? Did you put an aftermarket cap on it?

One good way to do it is the factory way, with an anti-siphon loop and vent down to the ground.

Thanks for the late ute pic, didnt see that one in the teck wiki.

So yes it will work, the tank and filler neck will still vent from the nipples on the vapor trap and the 13b will get its fuel.

Cant wait to turn the key now, getting close.