The fuel return can be tee'd into the fuel supply line upstream of the lift pump
. A lot of engines are plumbed that way, saves a lot of pipe or hose. A lot easier if you have multiple tanks with a feed selector, you don't have to do anything with the return. Only downside I know of is it takes a little longer to bleed air out, any air in the return will go through the system again. My boat has twin Perkins
mains and an Onan genset, all are plumbed this way.
I'm not sure this would work
with a common rail engine
, they return a lot of fuel. In mechanical diesels it's just a dribble.