Fuel Return Line question

[Mark Eaton]

I am installing a DART 347 with Holley Sniper EFI. Per Holley's recommendation I have run 3/8" hard send lines and 5/16" hard return lines under the chassis in the usual location. I will use the supplied 3/8" ID Vapor guard hose to connect to the fuel tank from the hard lines. Holley's instructions and their online video recommends drilling into the tank to place the below bulk head fitting for the return line. They even talk about drilling into the existing fuel pickup to place this bulk head fitting.



My question is it ok for me to skip this bulk head fitting and just run my return line into the return port which is already on the fuel pickup?

thanks,

Mark

[TexasAviator]

If you already have a provision for a return just use it. I would not add a fitting if you dont need to.

[Mark Eaton]

That makes perfect sense. I guess what was confusing me is that the guy in the Holley website video is holding a fuel pickup much like he FFR version and talking about drilling a hole for this bulk head fitting and ignoring the return line that is already there. I didn't know if there is something special about this bulk head fitting which makes it better than the regular return line.

[Boydster]

Its probably about the size. The Ford / FFR return is small, and obviously Holley wants a bigger return so there's no restriction. That fitting looks like a -6AN (3/8 inside) and the FFR return is 1/4". Even with your 5/16" return lines, this 1/4" thing becomes the tightest spot.

[RJD]

Since the FFR return port was smaller than the one recommended by Holley, I went ahead and drilled a new hole in the tank to incorporate the larger sniper return. There wasn't enough room to drill into the pick-up itself. I then sealed the FFR port. I also enlarged the access panel so I could access everything easier should I need to in the future. So far no leaks or fuel return issues.

D5AB4190-8078-4635-B8BC-5D909F689519.jpg

[rich grsc]

So how are you handling fuel aeration if you just dumping it back through the top of the tank?

[mike223]

Since the FFR return port was smaller than the one recommended by Holley, I went ahead and drilled a new hole in the tank to incorporate the larger sniper return. There wasn't enough room to drill into the pick-up itself. I then sealed the FFR port.

So how are you handling fuel aeration if you just dumping it back through the top of the tank?

I don't know that aeration is a problem, but I do know one thing that definitely can show up here.

If the returned fuel is not going directly in the sump (with the fuel pump) - then you are continually pumping the sump low.

This will show up in hard (autocross type) corners / acceleration / heavy braking as loss of fuel pressure.

Pipe the (aftermarket / prototype) return inside the tank to the sump - then you are continually over filling the sump (works better, and that was the OEM plan).


RJD's return looks like it might drop into the sump sitting still, but likely not under G forces (when you need gas in the sump)...

[RJD]

So how are you handling fuel aeration if you just dumping it back through the top of the tank?

Run the return line to the bottom of the sump. Unless you drive around on fumes, the end of the return line will be below the fuel level. Didn't consider high g forces, but I don't see myself racing either.

[Al_C]

I agree with Boydster: the return on the FFR tank fitting is 1/4. Nevertheless, I'd route your return line there anyway. Here's my thinking: I would have to believe that a good amount of the fuel traveling through the feed side will be consumed in the engine, so there shouldn't be that much on the return. Even with a 1/4 "bottleneck", I would have to believe that is sufficient to handle it. I'm using 3/8 for both feed and return, and my return goes into the tank fitting. Just my 2 cents.

[RJD]

The 1/4 return is probably fine, but I didn't want to redo it later if it wasn't. In any case, the mod was easy enough. Running the return to the bottom of the sump should take care of aeration issues and keep the pump from going dry in high g turns. This diagram is from the Holley Sniper instructions:

428CF4EF-C4EA-4F58-ACF3-43D38B305959.jpeg

[Mark Eaton]

Thanks everyone to your responses and PMs. I decided to go ahead and drill into the fuel pickup and install the bulk head fitting with 5/16" ID hose.

[TexasAviator]

Looks great

[rich grsc]

Good luck. I hope you don't have trouble with your tune, that is going to aerate the hell out of your fuel.

[cv2065]

As an FYI, here's the video that sold me on the Pro M Racing fuel pump hangar. Shows some of the aeration that Rich is referring to.

https://www.youtube.com/watch?v=Ium8jf4Jm04

[TexasAviator]

Something to remember here is stock pumps have been replaced with walbro pumps in stock hangers for decades. I am one that used them this way. It will be fine. If you want to mitigate it great but not necessary unless you are running your pump at wot with no gas in the tank down a track. ��

[Mark Eaton]

Rich and cv2065, Thanks for the input about aeration. I watched that youtube video, Interesting. This is the set up that has been recommended to me by Mike Forte and the Holley company so I'm going to go ahead and run it like this and see what happens. I'll try to remember to post my results.

[TMartinLVNV]

Mark, how has this been working for you? I'm at the decision point of leaving the 1/4 line in place (easy button) or enlarging it. I have the same motor and Sniper EFI as you.

Terry

[Mark Eaton]

Terry, I have 100 miles in go kart and no problems, it seems to be running great! No aeration problems that I can see.

Mark