Mine started leaking with the new fuel also, but only on cold days (32 deg or less). I relocated the lift pump with a Vulcan Big line kit and connected it directly to my already installed BD aux lift pump. Fuel pressure is lower now (from 28lbs to 13lbs at idle) but it seems not to run out on the top end now.

 

I have a 99, that really only leaks when I am pulling a 10k trailer. I mean it will cover most of the underside of the truck.
But when I am just running around town, not towing, I will only get a little drop or two that will build up on the bottom of the bellhousing, I have replaced the return line, But for the life of me I have no idea , other it is coming from the back of the engine, exactly where it is leaking fuel from , plus only mainly when I am towning>>>>
Anybody got any ideas>?
thanks,

 

Get some UV dye like used in AC systems (most are safe for fuel systems) and a black light and you will find your leak right away!