Return lines into fuel module questions

[015point9]

...Top of fuel module return lines…the smaller connection (roughly) is 5/16, the larger connection is 3/8.  With Airdog 100 where would you connect the larger line? 

Return from engine or return from  Airdog pump? 

 

...Being larger lines are usually better in most cases (fuel  line, exhaust, etc)

Would there be any benefit going to larger return lines to fuel module? 

 

 

Thanks

[notlimah]

I'm not sure how Airdog runs their lines. What's the instructions say?

 

You will still use one of the small return lines from the metal piping coming from the overflow of the VP and overflow from injectors at the back of the head. 

 

The other small line is the old supply line (mine had a blue clip and arrow pointing away from the fuel module) and you can scrap that line, or leave it. Just plug that hole so nothing can get inside your tank. 

 

 

More then likely will need to either modify your fuel basket with fittings to run your new supply and return lines from the Airdog. Or you put a hole in your tank and use that as a pickup (aka old school draw straw method) and cut your fill tube and run the return line there. 

 

 

***added pics for reference of how mine looked***

[015point9]

notlimah  “I'm not sure how Airdog runs their lines. What's the instructions say”? 

Never got instructions when it was installed. 

I did download some instructions and those instructions have return line from pump going into what Airddog calls “filler neck tee”.  I’m not using the filler neck tee.  One site shows they are using the large hole for pump return (see below)  But fuel system spec’s show “overflow valve release pressure”  of 14 psi.  So I thought larger of the two connections would get overflow from engine (biggest line).   Maybe it doesn't matter, being booth lines are going to end up in the basket?  

Also in your first pic the small connection (plastic fitting)  was a major pain to find and then order.  Mine were size 5/16 and Dorman part # 800-080.  

Thanks

 

Edited September 29, 2017 by 015point9

[Dieselfuture]

I don't like that picture at all. Where they cut the line and zip tide it to the side, that's not a good way of returning fuel from lift pump, first of very little will make it to basket and second it will make it foam. If returned to basket it needs to be as low as possible to bottom of it. And also if you don't do a full 1/2" in and out to all final destinations, you will have greater psi swing. Like @notlimah mentioned the only line on basket that should be reused is the smallest one used for vp and head return. In my case when I did my conversion draw straw 5 only came with one bung to go through top of basket so I had to make my own for return from lift pump, and I drilled out the bigger fitting that's used for factory outlet and used it for return, I did try using it as is at first and had issues. Later I complaind to Vulcan about it and sounds like he listened and now has 2 fittings to go through basket, now that's customer service. 

Edited September 29, 2017 by Dieselfuture

[dripley]

My AD installed using the existing return for the engine/vp return and the existing supply for the pump return. I then installed the included fitting for the new pickup line. I also got rid of the pump in the basket. The pickup on mine is only 3/8 where everything else was 1/2". Not sure why  but other than loosing a ump motor it has worked just fine for past 7 years or so. As far as returning to the filler neck I believe that still works fine for many others that have them.