Bypass Fuel Pressure Regulator Return Line, and entry back into the tank

[Propwash]

Hey Gent's,

Figured this question would more suite the racer's on this board. Here's my scenario; I'll be running a bypass fuel regulator on the backside of the fuel log tied onto my quickfuel Q950. Pump is a clay smith 6 valve mechanical 140GPH (non regulated). A) In this system, should my return line be the same size as the feed line? B) My fuel sending unit (located about mid tank) has a return port adjacent to the fuel feed port. I read the return line should come back in at the top of the tank. Would it work to just run the return line to the sending unit return port or go ahead and modify the tank to have a return port at the top? The return port bends down 90* inside the tank, seems like you would want the fuel to come back in that way to prevent fuel being shot down into the tank, causing it to bubble up/foam.

Thanks for the help. :notworthy:

 

[67 coronet]

as long as the return line cannot get submerged inside the tank you are fine.they say that because if the return gets submerged it takes more presure for the fuel to return to the tank.possibly causing back presure in the system.for optimal operation the return line should be the same size as the feed for the same reason.

 

[RustyRatRod]

As long as you run the regulator on the return side, you can run the same size return line, because you will be using the regulator as the return orifice. I said orifice. heh heh heh huh huh huh.

 

[Budnicks]

Prop; That was the port I used in my 68 RR 479ci/6bbl with an electric S/S Aeromotive 175gpm/12-18psi pump & Holley By-pass style regulator, set at 7# psi, with a 3/8"/#6an main line & a 1/4"/#4an return line into the Mancini Racing 3/8" sending units, return line port that is 1/4"... it works fine... your supposed to use the same size line according to Holley, but I've used a smaller return line a few times & just adjust the regulator accordingly, with a gauge at the regulator to see what psi it's flowing at the source... no problems yet

 

[Budnicks]

not the same sending unit, on a 68-70 RR, GTX, Satty, Belve., but a photo of the extra line/fitting going back into the fuel tank, via the sending unit fitting bungs/nipples...

 

[benno440]

the manual shows that 2nd port as a vent line not a return as that is submerged in fuel and wouldnt work as a return?
i welded a 1/4" bung into my ful filler neck to run thw 4 an return line

 

[Propwash]

Thanks for the input guys! Really appreciate it.

 

[RustyRatRod]

the manual shows that 2nd port as a vent line not a return as that is submerged in fuel and wouldnt work as a return?
i welded a 1/4" bung into my ful filler neck to run thw 4 an return line

That's when you get the wiz wheel out and cut the "vent" line off just under the plate and then call it a return.

 

[Furyous]

I gave Rusty a thanks for using the word orifice...lol

 

[65hemi]

I used 1/2" supply and return lines with my Aeromotive pump and reg. I removed the 1/4" vent port on the sending unit, opened up the hole and installed a 1/2" port for the return line. Some trial and error to make sure the sending unit can still be installed in the tank. No mods to the stock tank.

 

[Propwash]

Did you weld or solder the 1/2" port in the sending unit 65Hemi, or just go with a bulkhead type fitting with seals?

 

[65hemi]

Bulkhead fittings are too big. I tried to solder but did not work. Ended up using JB weld.

 

[Budnicks]

Bulkhead fittings are too big. I tried to solder but did not work. Ended up using JB weld.

I was going to say the same exact thing, bulkhead fittings are too big... Prop you could always weld one in get a Stainless or a Steel A/N fittings, not too sure about the JB Weld stuff long term in fuel... never tried it

 

[Propwash]

I was going to say the same exact thing, bulkhead fittings are too big... Prop you could always weld one in get a Stainless or a Steel A/N fittings, not too sure about the JB Weld stuff long term in fuel... never tried it

Bud, Pretty sure i'm just going to drop the tank and weld in a -6AN bung like you mentioned. The Holley billet regulator i'm going with says to have at least the same size return when running a mechanical pump. The electrics can get away with a smaller return being the typically higher PSI vs. the mechanical. I'm no fuel pump engineer so i'll just stick with what they have to say and play it safe. No biggie to take off a couple J-bolt's, drill a hole, weld in a bung and call'er done. No fuel back there as of yet. Think I'll mount it high, centered and tac on a 3/8" tube for the inside to direct the fuel to the bottom of the tank. Sending unit faceplate doesn't have much room at all, like 65hemi mentioned. Think i'll pass on the JB Weld and put a real weld in.

BTW..Would it be safe to run -AN Stainless braided line back to the tank as the return line? I already have a pre-bent steel feed line. Just wondering, would cost about the same if not cheaper and would be easier to finagle around the rear hump to the tank area.

 

[Budnicks]

Bud, Pretty sure i'm just going to drop the tank and weld in a -6AN bung like you mentioned. The Holley billet regulator i'm going with says to have at least the same size return when running a mechanical pump. The electrics can get away with a smaller return being the typically higher PSI vs. the mechanical. I'm no fuel pump engineer so i'll just stick with what they have to say and play it safe. No biggie to take off a couple J-bolt's, drill a hole, weld in a bung and call'er done. No fuel back there as of yet. Think I'll mount it high, centered and tac on a 3/8" tube for the inside to direct the fuel to the bottom of the tank. Sending unit faceplate doesn't have much room at all, like 65hemi mentioned. Think i'll pass on the JB Weld and put a real weld in.

BTW..Would it be safe to run -AN Stainless braided line back to the tank as the return line? I already have a pre-bent steel feed line. Just wondering, would cost about the same if not cheaper and would be easier to finagle around the rear hump to the tank area.

yeah it is safe, I used Odel clamps every 2 or so feet, to hold both lines in place, I'm going to repace them with dual aluminum trick looking ones sooner or latter, just keep it away from exhaust heat & abrasion, make sure the fitting are all the way installed on the hoses etc.... which I'm sure you already knew anyway, I used Aeroquip Starlight Race flex line both ways for pump carb/supply & the by-pass return lines... it aint cheap thou, a well done steel or aluminum solid line will work too, might radiate heat a little more thou... I'm kind of ****, about any extra heat in the fuel system, it aint a good thing... the tube to near the bottom of the tank, to help keep the fuel from aerating/foaming is also a very good idea too, especially with a high volume/pressure electric pump, mechanical pump "maybe not so critical", it couldn't hurt... my $0.02 cents

 

[Propwash]

Very Much appreciated sir! :icon_salut:

 

[Budnicks]

Very Much appreciated sir! :icon_salut:

your welcome, glad I could help... well give you a sounding board, to bounce ideas off of anyway...LOL...

 

[Propwash]

I'm going to repace them with dual aluminum trick looking ones sooner or latter, just keep it away from exhaust heat & abrasion, make sure the fitting are all the way installed on the hoses etc....

Here's what I ended up ordering Budnicks....Not aluminum, but Stainless Steel instead. They come in packs of 12. By far best price I found for them on the internet:

http://guiltybydesign.net/index.php?cPath=50_34_141

 

[Budnicks]

Here's what I ended up ordering Budnicks....Not aluminum, but Stainless Steel instead. They come in packs of 12. By far best price I found for them on the internet:

http://guiltybydesign.net/index.php?cPath=50_34_141

Prop, thanks I'll check them out

 

[SUPERSTOCKRACER]

personally this is the best way to go. return system off of regulator, .all product engineering stuff. best out there. i'm a dealer too.