fuel return line

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diymirage

diymirage

HP@idle > hondaHP@redline
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so, im a slow learner, but i just had an idea
i think it is time to upgrade the stock fuel lines
as it sits right now, im running 5/16th from the tank to the mechanical pump, and AN-6 lines from there to the (non return) regulator, and into the carb

so, since im thinking or replacing the stock fuel line with a 3/8th line...would it be possible (and smart) to leave the stock line in place, and plumb it in as a return line?

swap out the regulator for a return style unit, and replace the sending unit with one with a return inlet, and done, right?
 
If your 5/16 line is in good shape I would use it as a return. Running a return line is a good idea with the fuel we have today. And if you upgrade to some type of injection in the future you may need a return.
 
i dont know how good a shape the stock line is...thats one of the reasons im replacing it

another possible issue is the regulator im looking at (mr. gasket 2015) claims i need at least a 3/8 return line in order to regulate pressure properly

any thoughts on that?
 
I have no idea on that regulator as I have never run it, maybe somebody with that type will reply. Would it be worth your while to get 2 pre made 3/8 lines?
 
Since I have zero intention of ever racing NHRA I used 3/8 nylon 12 EFI line for both with a restrictor in the return to give me the pressure my carb needs so I don't need to run a regulator.
I just put a gauge on the supply side and drilled the restrictor until I had 6psi at the supply side.
Removed the gauge and done.

Just an idea.
 
at 60 bucks a piece...id rather not
but even then, all the sending units i saw, only list a 1/4 inch return, so there is always that restriction

i would like to pass tech, even on unsanctioned test and tune nights
 
TrailBeast said:
Since I have zero intention of ever racing NHRA I used 3/8 nylon 12 EFI line for both with a restrictor in the return to give me the pressure my carb needs so I don't need to run a regulator.
I just put a gauge on the supply side and drilled the restrictor until I had 6psi at the supply side.
Removed the gauge and done.

Just an idea.
Click to expand...

I have a return "port" on my tank. Not sure the correct term of this port but basically have two ports on my tank. One is used for to feed the carb and the other (return) I have capped off at the tank. Been thinking installing a return line to the fuel system. Your method sounds pretty interesting. Like to have more info on the restrictor you used. Right now I have 7 psi at the carb without a pressure regulator using mechanical pump. Had one of those Carter mechanical fuel pumps on there but it was junk. It never had good fuel pressure. Went with a standard pump and it works like a charm.
 
mullinax95 said:
I have a return "port" on my tank. Not sure the correct term of this port but basically have two ports on my tank. One is used for to feed the carb and the other (return) I have capped off at the tank. Been thinking installing a return line to the fuel system. Your method sounds pretty interesting. Like to have more info on the restrictor you used. Right now I have 7 psi at the carb without a pressure regulator using mechanical pump. Had one of those Carter mechanical fuel pumps on there but it was junk. It never had good fuel pressure. Went with a standard pump and it works like a charm.
Click to expand...

The restrictor is just a 1/2 inch of brass rod drilled to the size it needed to be, and is inside the rubber section of EFI hose that connects the nylon line to the T for the return.
On my sender I drilled it out and put screw together nipples for the feed and return.
 
Bad Sport said:
Yup, it sure does. Well.......grrr.
Click to expand...

The company that is selling the sending unit has it labeled wrong or they are mainly concerned about the primary fuel line and label it "3/8 with 2 lines". They should state that it is "3/8 with a 1/4 return". If the return is actually 1/4 .... I don't know for sure.....:rolleyes:
 
Last edited:
anyone familiar with the Holley 12-881 fuel pressure regulator?
their info sheet does not mention electric or mechanical pumps but it does seem to have the 3 ports (in, out, return) i need
 
No need for a return style regulator. Just plumb a return line T'd off of the fuel line near the carb with a .060 or so restrictor in it like Trailbeast recommended. Connect that to your stock 5/16 line. Then run a new 3/8 line for the supply side. That's about as cheap as you can get to add a 3/8 supply and have a return to circulate hot gas. You already have a working regulator. Why buy another one.
 
mopowers said:
No need for a return style regulator. Just plumb a return line T'd off of the fuel line near the carb with a .060 or so restrictor in it like Trailbeast recommended. Connect that to your stock 5/16 line. Then run a new 3/8 line for the supply side. That's about as cheap as you can get to add a 3/8 supply and have a return to circulate hot gas. You already have a working regulator. Why buy another one.
Click to expand...

You can lead a horse to water but...:D
 
mopowers said:
No need for a return style regulator. Just plumb a return line T'd off of the fuel line near the carb with a .060 or so restrictor in it like Trailbeast recommended. Connect that to your stock 5/16 line. Then run a new 3/8 line for the supply side. That's about as cheap as you can get to add a 3/8 supply and have a return to circulate hot gas. You already have a working regulator. Why buy another one.
Click to expand...
Allrigt...I'll run with this thought
The regulator I have now has two outlet, but one is closed of
If I were to use that port, and run both a return line and a restriction in it...would the gauge on the carb still be accurate?
It should, right?

And would that turn my deadhead regulator into a return style one?
And...would the adjuster on the still be functional, perhaps for fine tuning?
 
diymirage said:
Allrigt...I'll run with this thought
The regulator I have now has two outlet, but one is closed of
If I were to use that port, and run both a return line and a restriction in it...would the gauge on the carb still be accurate?
It should, right?

And would that turn my deadhead regulator into a return style one?
And...would the adjuster on the still be functional, perhaps for fine tuning?
Click to expand...

That's the same idea as using a filter with a vapor return nipple on it near the carb. It may be better to T-off the line closer to the carb with a restrictor of course instead on going off the regulator. The pressure regulator regulates the pressure in the whole system, so if it doesn't matter where it's at. The adjuster would still be functional.
 
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