I have removed the fuel rail and all associated components from my parts ZX. There is about 5 gallons of fuel in the tank.

 

I intend to drain and remove the tank this weekend.

 

I don't particularly want to leave the fuel inlet/outlet lines open. If I plug the fuel lines to and from the fuel rail, and leave the gas filler cap off will that prevent any fuel pressure from building up over the next few days?

That will be fine. Unless you get very high temperatures in Seattle this weekend, there is no fuel pressure issues you need to worry about. My favorite stupid boo boo is to leave the lines un capped, then move the car where the angle changes and later have fuel dribble out from gravity feed without noticing it for a while. Pressure buildup is not an issue.

Excellent. Thanks.