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idleup

Well Known Member
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
 
fuel return line

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

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.
 
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.
 
Flexiblity for me

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.
 
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 [email protected]
 
RV7Factory said:
In addition, Captain_John put together a good post with pictures on another forum.
Click to expand...

HEY! I resemble that comment!

Roger, after considering the cost of the duplex valve and the tight quarters for bending requirements, I may do just the same!

:) CJ
 
Brad,

Did you use the same AN833-6D BLKHEAD 90 DEG. FITTING that is used on the fuel pickup for your return line fitting?

Do you have any pictures?

- Matt
 
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Not sure...

A few months ago I had this all planned out, then while in the midst of assembling the tanks, I packed it all up and put it in storage while we moved. So while all the parts are here, and the system designed, I haven't gotten around to putting it all together. Not wanting to have to place two orders, I purchased some AN832 straight and AN833 90-degree fittings. When I get around to putting it together in the next few weeks, I should have a better idea of which fitting will work better.

In the meantime, I have been studying DWG 36 trying to figure out if the straight or 90 fitting would be best. I am thinking the the 90 might be easier. The plan would be for the vapor/fuel return line come straight out of the fuse and bend towards the fitting. If I use the straight fitting, I cound end up having to bend the tubing into an S to make the connection... I think one 90-degree bend would be better (easier) than an S. Bottom line is I haven't decided. Sorry... I am not much help. :confused:

PS - This discussion is good... it is helping me get my head back in the game after a few months away from the project.
 
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Captain_John said:
...after considering the cost of the duplex valve and the tight quarters for bending requirements, I may do just the same!
Click to expand...
Hey CJ, you're part of the reason I decided to go the route I am going. So no whimping out on us now... misery loves company! ;) :D :p
 
Here is my parts list that I just ordered tonight. I am going to use a -6D elbow fitting and put it near the other vent fitting. I want to keep it high so there is no back pressure as was mentioned in another post.

? AN833-6D Elbows
? AN924-6D Nut
? AN818-6D Nut
? AN819-6D Sleeves
? Fuel Tubing (3/8 x .035 Soft Aluminum)
? SB500-6 Bushings (where vent tube passes through the first tank rib to go to the 2nd bay)
? AN929-6D 3/8? AN Cap (to cap off lines if they are not used)
? AN Spacer, 6D

I also purchased the leak test kit from Van's after finalizing this and completing the SB on the safety wiring all the parts for for doing both wings plus extra bushings plus extra parts was $25. Other than the fact that you are punching another hole in your fuel tank, I dont see why people building would not want to do this just in case they implement a purge system or an active return line system...

- Matt
 
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Looks almost identical to my order. If you get there before me, let me know how it works out, and good point about keeping it high.
 
This thread came at a good time. I need to be thinking about what I'm gonna do since I'm currently installing and sealing ribs. Guess I should decide before the rear baffle goes on, huh! :eek:

Good info on what to order!
 
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