is there a return fuel line in carb setup?

95conv5.0 · Oct 15, 2006

because my carb regulator has 3 ports, in/out and one on the bottom, its just a holley maxpressure! do i only use the in and out and thats it?

Dark Knight · Oct 15, 2006

If it's 510-12-803 then the port on the bottom is the inlet, the two on the sides go to the carb. You can plug one if you only need one.. They're set up for a holley carb with one line to each bowl.

If you have Part #: 12-803BP, then it has a bypass and uses a return line

jrichker · Oct 15, 2006

No return line is used on a properly done carb setup. The single low pressure pump that is required for carb setups puts out less than 10 PSI.

rd · Oct 15, 2006

Use on outlet for the carb and the other for the nitrous plate.

tylerrocks · Oct 15, 2006

or a fuel pressure gauge or plug it

billison · Oct 15, 2006

I know on my car it had the return line so i used it and i've not had any problems with it

Dark Knight · Oct 16, 2006

jrichker said:
No return line is used on a properly done carb setup. The single low pressure pump that is required for carb setups puts out less than 10 PSI.

Actually, a good carb setup does use a return line. Even my carbed 84 has a factory return line from the pump.. you dont always NEED it, but circulating cooler fuel to the carb is always a good idea..

EMW150 · Oct 16, 2006

Dark Knight said:
Actually, a good carb setup does use a return line. Even my carbed 84 has a factory return line from the pump.. you dont always NEED it, but circulating cooler fuel to the carb is always a good idea..

That's correct. A properly done carb setup requires a return line if you want any real volume. I run a BG220 HR pump on my car which requires a #8AN supply and a #10AN return. That way the pump runs at full volume all the time and returns what it doesn't need to the tank.

thehueypilot · Oct 16, 2006

EMW150 said:
That's correct. A properly done carb setup requires a return line if you want any real volume. I run a BG220 HR pump on my car which requires a #8AN supply and a #10AN return. That way the pump runs at full volume all the time and returns what it doesn't need to the tank.

Shouldn't the return be smaller than the supply? Or are you running the return line from the pump to the tank instead of the regulator to tank which is located at the front of the car?

billison · Oct 16, 2006

This may be the wrong way to do it, but unstill i can buy a bypass regulator, i have my feed and return ran to a "T" and have the regulator after that then to the carb, that way all unused full goes to the tank, it looks like crap though, but if you can get what you need now, get a bypass regulator, it'll have one "IN" and 2 "outs" one to the carb one back to the tank

EMW150 · Oct 17, 2006

thehueypilot said:
Shouldn't the return be smaller than the supply? Or are you running the return line from the pump to the tank instead of the regulator to tank which is located at the front of the car?

The #8 supply runs from the pump to a bypass regulator. I have two #8 supplies to the carb (upstream of the bypass regulator) and then the #10 return runs back to the tank. BG wants the larger return line because the fuel isn't under as much pressure on the return side of the bypass regulator. If not you could get an increase in pressure under certain conditions.

thehueypilot · Oct 17, 2006

EMW150 said:
The #8 supply runs from the pump to a bypass regulator. I have two #8 supplies to the carb (upstream of the bypass regulator) and then the #10 return runs back to the tank. BG wants the larger return line because the fuel isn't under as much pressure on the return side of the bypass regulator. If not you could get an increase in pressure under certain conditions.

I am running #10 from the tank to the pump and #8 from the pump to the regulator and a pair of #6's to each carb bowl. I was thinking of running a single #6 from the regulator (return port) back to the tank since that is what Ford originally did. I am not having a fuel starvation issue but thought this might help the pump and fuel run cooler but noe sure of the return size?

EMW150 · Oct 17, 2006

thehueypilot said:
I am running #10 from the tank to the pump and #8 from the pump to the regulator and a pair of #6's to each carb bowl. I was thinking of running a single #6 from the regulator (return port) back to the tank since that is what Ford originally did. I am not having a fuel starvation issue but thought this might help the pump and fuel run cooler but noe sure of the return size?

That may be a good idea, that's the whole idea behind the BG220 HR pump that I run. It's made for lower pump and fuel temperatures for extended street use. My outlets to carb are #6 also, not #8 like I previously posted. Here's a link to the BG pumps and recommended installs.

http://www.barrygrant.com/pages/manuals.aspx

thehueypilot · Oct 17, 2006

Ahhhh....Now that is totally backward from what I was thinking since the regulator is only on the return side. Which brings up another question about controlling fuel pressure? If you adjust the fuel pressure to 9 psi max will that setup close off (regulator) if it starts to drop?

85ragtop · Oct 17, 2006

I was running a 14psi in tank pump and a Holley regulator. I used a return to feed back the extra, and I never had a problem.

EMW150 · Oct 17, 2006

thehueypilot said:
Ahhhh....Now that is totally backward from what I was thinking since the regulator is only on the return side. Which brings up another question about controlling fuel pressure? If you adjust the fuel pressure to 9 psi max will that setup close off (regulator) if it starts to drop?

Yeah, it's different. Think of it this way. The pump is flowing full volume 100 percent of the time. The bypass regulator acts as a restriction on the return. So when you're lowering the pressure you're actually just allowing more fuel to bypass hence lowering the pressure without effecting the volume.

Dean85GT · Oct 17, 2006

I just run a line from my tank to my mechanical holley fuel pump. From there its 3/8ths braided to the carb. I dont have any return lines and its fine.

thehueypilot · Oct 17, 2006

EMW150 said:
Yeah, it's different. Think of it this way. The pump is flowing full volume 100 percent of the time. The bypass regulator acts as a restriction on the return. So when you're lowering the pressure you're actually just allowing more fuel to bypass hence lowering the pressure without effecting the volume.

I'm used to just deadheading the pump but at 15psi it does build up heat and starts to cavitate which could fall behind in volume when really needed. I bracket race so I'm always looking to be more consistant on temps. and that is one area that I think can be improved by adding a return. It would probably increase the life of the pump as well.

maj · Jan 17, 2025

Yeah on a 94 GT mustang opal Frost with black stripes it's got a pretty good size cam in it probably equal to like a b303 it's a lunatican voodoo I think the max lift is like 554 or something like that but I'm wanting to do a carburetor swap I want to put a carburetor on it and I was just wondering do I plug the return line from the fuel injection system, then run the supply line into a fuel regulator then to the carb for about 7 lb of fuel pressure.

maj · Jan 17, 2025

Thank you for letting me be a member at Stang Net.com

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