2 line vs 3 line fuel pump

[rauto13]

I have moved the fuel tank under the bed on my 72 Chevy, the truck originally had the three line fuel pump. When I first moved the tank, I used a plastic tank that had provisions for the vent and also for a return line. I switched to an aluminum tank from Classic Performance and now I have a just one provision for either a return line or vent. I have chosen to use this for the vent, and I am not going to use the return line.

The truck still has the fuel pump with the third line, which has been capped. I have a two line fuel pump ready to install. The question is: Should I run a tee and use the top hole in the tank for the vent and return line or, just install the two line fuel pump and forget about the return line.

Ever since I first installed the plastic tank, the truck has run somewhat rich. I have an Edelbrock carb on an Edelbrock intake. I have switched to the smallest metering rods available and also turned the enrichment screws in to lean the mixture (about one full turn). The truck would always start right up if it ways started every day, but if it sat for three or four days, I would have to crank and crank, like the truck was out of gas, to get it to start. After it had been started that day, it ran good (a little rich) and was easy to start the rest of the time.

I also run through spark plugs about every six months, with very little driving, mostly in town.

Any suggestions would be greatly appreciated.
Sorry for the long post.