There are two fuel lines coming out of the firewall going to the fuel pump and filter in my 74 1.8 with L-jet. They run side-by-side. which line is the one toward the driver's side? Which is the one toward the passenger side? Also, how does the "Y connecter" get hooked up to the pump? Thanks.

"toward the drivers side"???? they should both run parallel towards the fuel pump location in the front corner of the engine compartment on the passengers side. the "Y" goes on the return side of the pump. better to look at pelican diagram than for me to try to explain and give false info. one big question that needs to be answered is which line is feed and which is return...

I guess this is what I mean. The lines in my car both appear to be the same diameter so I can't use that as a means of determining supply and return lines.

The hard lines coming out of the fire wall are different sizes. The 8mm hose is the draw and 7mm is the return to the tank. Make sure you hook them up right because the return side doesn't have a screen over it in the gas tank and you can end up pulling crud from your tank.
-Mike D.

So where does the supply line go to? The fuel filter? Then out to where? The y fitting? Then one side to the pump and one to the fuel rail? Three holes in the pump is very confusing.

Like this?

Got it running. If I remember right, this is what I did.