I am guessing that the seeping cloth-braided fuel lines on top of the tank (on the "Y" connector) are 5mm??

FAIL.

12mm and 14mm.

And you're not likely to find metric sizes at the local parts store anyway. IIRC, I used 1/2" or 7/16" fuel line for both which was hard to find. I think I found it at Napa.

stink, i got the big F. so, are the cloth-braided lines needed? or can i just use the same 12mm that i am running from my tank to the external pump? thanks

they don't need to be braided. Its just a vent. the 12mm stuff that you're using for the fuel line is probably higher grade than the original vent lines.

I've heard bmw didn't use fuel grade hose for the vents. :dunno

If you look on realoem it tells the sizes. The 12mm is no problem (1/2 inch) but the 14 is hard to find. Don't let someone fool you into using a heater hose, it won't last any time.

The oem braided hose is a lot more $$ per foot than the non-oem hose. Always make sure the hose is correct for the application. I know the yellow striped braided is even more $$ because its for diesel fuel.