I searched through the coast guard documents and couldn't find anything that addressed a fuel return as being illegal. I attached a link to the regulations for you. I'm very interested in knowing where this requirment is.

http://www.uscgboating.org/regulatio.../fuel/fuel.htm

I'll have to take a look though them to see if I can find it. I was told by my insurance agent many years ago not to put a return line in the boat since all pressurized fuel lines must be within 12" of the motor.

It's been a while, I'll call again and get clarification.

If you think about it...a requirement that all pressurized fuel lines be within 12" of the motor is all but imposssible. How would a large cruiser with 300 gallon tanks midships pump the fuel? These pumps don't like suction and the coast guard regs do not favor putting the pump low because of siphon issues. The regs do address the pump being inside the fuel tank and actually specifically approves that installation.