I'm swapping fuel lines from a crew cab frame over to a reg cab frame, and need to shorten them. I want to do something like the spliced trans lines pictured below, where I run AN fittings and a short length of AN line to splice the lines back together after cutting out a section. After some searching I've found the the supply line is 1/2", but I have not been able to find any info about the return line. Just need to know what the OD is. Anyone know?

 

1/2 feed and 3/8 return seems to be the consensus from a couple other sites I posted on.

 

What pressure is in that line? From what i have read that type of adapter are not rated for high pressure.

 

For example. A 1/2 tube to -8an is only rated for 50psi.

Earl's Performance AN to Tube Adapter Fittings 165108ERL - Mobile SummitRacing.com

 

They should be fine. Even with a lift pump, the diesel lines are only pressurized to something like 15 psi. Without a lift pump, the mechanical pump on the engine actually draws the fuel from the tank, so there would be slightly negative pressure in the lines.

I've actually had a few people recommend just replacing the factory hard lines with diesel rated fuel injection rubber lines, and putting a hose clamp on to hold them to the factory push-lock fittings on the engine side and fuel cooler side. Personally, I'd rather keep the factory hard lines, so I'm going to do it this way instead.

 

When splicing the lines a thought in my head would be to do it closes to where you would be putting the lift pump so you wouldn't have to much work to put it in