Question on Fuel Return Line...

idleup · #1 06-06-2006, 12:35 AM

I am taking off my fuel tank access plates to comply with the SB and was wondering if I need to install a fuel return line. I am planning on installing an IO-360 and heard that it needs a return line. Searching the forums I havent found a lot of people adding them. The threads I did find tend to deal with the Subaru engines. So my question is do I need them? is this a good time to install them? and are there any photo's/instructions on how to do it?

THanks,
Matt

rv8ch · #2 06-06-2006, 02:39 AM

Now is the time to install it, that's for sure! The best way to find out if you need one is to check with the fuel injection supplier you plan to use. Some return the fuel to the tank, some to the line before the fuel pump. It doesn't hurt to return the fuel to the tank, but requires a more complex plumbing job, and a more expensive fuel selector.

I installed a fuel return line for my Subaru, and it was not as big a deal as I expected it to be.

lrfrey · #3 06-06-2006, 06:50 AM

Go to the lycoming group at yahoogroups for a good answer by Don from Airflow Performance or Precision (sorry can't remember which.)
Larry

Jekyll · #4 06-06-2006, 08:30 AM

Matt:

It depends on the injection system you use. Precision SH injection systems do not need a return line (I don't know the requirements for all sytems). If you are buying a new engine, you can configure it with the system of your choice - talk to the front office of Mattituk, Aero Sport, Penn Yann, Performance or Superior (and others) and they'll inform you of your options.

If you feel confident that today's engine choice will be the same tomorrow, you can configure your fuel system accordingly. If not, put in a return line now so you can accommodate any future choice.

I've got a QB and didn't relish trying to install a return line at that point so I committed to the Precision SH system and never looked back.

Jekyll

idleup · #5 06-06-2006, 11:37 AM

I think it would be a good idea to install it and then cap it off later if I dont use it like you suggested.

Does anyone have instructions/pictures on how and where to install it?

- Matt

rv8ch · #6 06-06-2006, 11:43 AM

Here's how I did it:

http://www.rv8.ch/article.php?story=20040704204434728

RV7Factory · #7 06-06-2006, 12:16 PM

The topic of fuel/vapor return lines has been discussed a lot here at VAF, and there are some very good posts on the subject. Do a Search, and I'm sure you will find it useful.

In addition, Captain_John put together a good post with pictures on another forum.

idleup · #8 06-06-2006, 03:13 PM

Yeah, I have read most of them. I did notice that you decided to go with -6 instead of -4 fittings. Which fuel selector are you using? Does the andair use a -6 on the fuel fitting? I dont want to have to use a reducer on the line.

RV7Factory · #9 06-06-2006, 03:29 PM

I decided to use -6 simply for long-term flexibility. I haven't decided on an engine/FI system yet, so at the suggestion of another smarter builder, I decided to go the -6 route to ensure that I was covered no matter what FI system I eventually select. According to Andair, their valves are available with either -6 or -4. If you are going with a simple purge/vapor return system, -6 is probably overkill. The newer constant pressure systems (e.g. ECI), or whatever they are called, might require larger plumbing because they are returning larger amounts of unused pressurized fuel to the tanks. Again, it all came down to flexibility for me.

Roger Moore · #10 06-06-2006, 04:30 PM

Fuel Return, I installed a XP360 with a Bendix PS5 in my RV4 and had to install a return line. I installed the return to the left tank so when I fill up I do not fill the left tank to full to allow room for the return. Works fine. Roger Moore RV4DRVR@aol.com