Fuel return line

temason · Post by **temason** » Wed Feb 11, 2015 8:29 pm

I feel like this topic is often discussed but I don't feel like a definitive answer is given...
I'm converting a 79 with electric fuel pump, to a DFEV carb that has but one connection for fuel. I have read to simply cap the return line (no ill effects), OR to get a 3 way fuel filter and connect return line there. Pros and cons? Why wouldn't I just cap it?
Thanks

So Cal Mark · Post by **So Cal Mark** » Wed Feb 11, 2015 11:16 pm

fuel recirculation helps prevent vapor lock, use a 3 way fuel filter

bradartigue · Post by **bradartigue** » Thu Feb 12, 2015 7:46 am

Agree - use the 3 way filter. The menage a trois. We've found that when you don't use the fuel return circuit the engine bay fuel smell is quite bad.

temason · Post by **temason** » Thu Feb 12, 2015 9:57 am

Mark and Brad
Thanks for the replies. Makes sense, that's what I will do!

philbert · Post by **philbert** » Thu Feb 12, 2015 10:14 pm

Hi guys, can you describe this 3 way fuel filter please and what exactly it is connected to?

124JOE · Post by **124JOE** » Fri Feb 13, 2015 12:31 pm

its a doge filter you can find at autozone it has an inlet at the bottom and an outlet at the top
and on the side near the top there is one extra nipple for the line that feeds back to the tank

70spider · Post by **70spider** » Fri Feb 13, 2015 12:53 pm

I just recently put a 32/36 DFEV and ran into the same problem. I got this filter http://www.amazon.com/FRAM-G3583DP-In-L ... B000C2ZJRU and it works great.

philbert · Post by **philbert** » Fri Feb 13, 2015 6:02 pm

Thanks guys, I get it now. Except for the part about the doge filter.

bradartigue · Post by **bradartigue** » Fri Feb 13, 2015 6:10 pm

philbert wrote:Hi guys, can you describe this 3 way fuel filter please and what exactly it is connected to?

It has two big pipes and one small one. The big ones are fuel in and out. The little one is fuel return. When pressure in the filter hits about 5psi a valve open and fuel is sent to the tank. Keeps things circulating.

vandor · Post by **vandor** » Tue Feb 17, 2015 10:11 pm

I just bought one. It is GK brand, part number 33086. Fram part number G3587, AC part number GF485.
Fits a late 80s Chrysler sedan.

sptcoupe · Post by **sptcoupe** » Wed Feb 18, 2015 8:20 am

So where would you place the three-way filter on a dual carb setup with electric fuel pump and in-line filter located at the rear, near the fuel tank? After the fuel pressure regulator and fuel pressure gauge, but before the carb inlet? Between the fuel pressure regulator but before the fuel pressure gauge? After the in-line fuel filter in the rear, near the pump?

I like to have the fuel moving through the carbs on the way back to the tank (which is what I have now) as it helps keep them cool, so in addition to eliminating vapor lock issues, it prevents heat soak/percolation issues. The fuel now returns via a hose fitted to the rear-facing outlet of the #2 IDF.

Csaba - you know my set up. What do you think? Do I need to change it?

vandor · Post by **vandor** » Wed Feb 18, 2015 7:42 pm

> Between the fuel pressure regulator but before the fuel pressure gauge?

That's what I would do.
Or you could add an outlet nipple to the second carb and put a restrictor in the line. I think we had it setup like that for a while.

sptcoupe · Post by **sptcoupe** » Wed Feb 18, 2015 11:18 pm

I have the restricted outlet nipple on the out of the back carb now. So no need for the dual outlet fuel filter?

vandor · Post by **vandor** » Thu Feb 19, 2015 1:36 am

sptcoupe wrote:I have the restricted outlet nipple on the out of the back carb now. So no need for the dual outlet fuel filter?

No, it's for carbs that do not have a return line.

RoyBatty · Post by **RoyBatty** » Thu Feb 19, 2015 12:13 pm

Ok then,
On my 75, I installed the dual idf 40s and capped of the return line.
Would it be better for me to go ahead and install a restricted fitting in the back of the rear idf and connect that to my return to the tank?

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