D.I.Y Adding a Return fuel line

People have been asking for my version of the fuel return so here it is:


So today even though I’m busted up from surgery I decided I would finally finish my fuel system. I had pretty much been done and just awaiting some new parts from Hybrid Racing.


There are a lot of parts involved in doing a full fuel system with return line. This process is not cheap. I’ve seen people spend up to $1k in just their fuel setup. I believe I spent almost $600 myself. Here are some of the parts.. I know I’ll be missing some misc…

After Market Fuel Rail
Fuel Pressure Gauge
Fuel Pressure Regulator
Inline Fuel Filter
Aftermarket Fuel Pump
20ft -6an Fuel Line
3/8” and 5/16” submersible fuel hose
lots of AN fittings (I’ll explain all I used in the DIY steps)
Hose clamps
Zip Ties


Here is what I can remember for the fittings I used...

Straight -6an fittings [4 Total]
-Pump (1x)
-Filter (2x)
-FPR (1X)

45* -6an fittings [2 total]
-Rail (1x)
-FPR (1x)

90* -6an fittings [1 total]
-Rail (1x)

-10an to -6an adapter [2 total]
-Filter (2x)

-8an to -6an adapters [4 total]
-Rail (2x)
-FPR (2x)

90* male to male fitting [1 total]
-pump (1x)

-6an to 3/8th nipple [1 total]
-pump (1x)

-6an plug [1 total]
-FPR (1x)
http://i918.photobucket.com/albums/a...n/100_6324.jpg

http://i918.photobucket.com/albums/a...n/100_6458.jpg

So lets get started…. The first thing you need to do is install your new fuel pump. I already have a DIY on installing a pump without a return. So start with this DIY to take out the pump and modify the cage
http://forums.clubrsx.com/showthread.php?t=738511



Now lets start the new process!
So I started my new fuel setup today.

Basically I pulled the pump back out. I already had a 255lb pump installed. But now I'm adding a new feed and return setup. So first I dismantled the fuel pump assembly

http://i918.photobucket.com/albums/a...n/100_6345.jpg

Then I went and place the nut on the bottom where I will be drilling. You will need this nut. You will also need a 90* male to male 6an fitting to go through the pump. Also I used a 6an to 3/8” barb fitting inside the pump. You can see the fittings in the picture above.
http://i918.photobucket.com/albums/a...n/100_6346.jpg

Then I drilled out the hole. I used a blade to clean up the burrs and etc
http://i918.photobucket.com/albums/a...n/100_6347.jpg

Now I placed my new fitting threw the hole
http://i918.photobucket.com/albums/a...n/100_6348.jpg

http://i918.photobucket.com/albums/a...n/100_6349.jpg


Now I attach the barb connector and redo the hoses. I use the stock feed nipple as the return now and the pump goes to the new added barb fitting.
http://i918.photobucket.com/albums/a...n/100_6351.jpg

http://i918.photobucket.com/albums/a...n/100_6350.jpg

And put the pump back in the tank. Now to start the lines....

First thing I did was mount my inline fuel filter. First I wanted to wrap it in hose so it doesn't vibrate
http://i918.photobucket.com/albums/a...n/100_6352.jpg

http://i918.photobucket.com/albums/a...n/100_6353.jpg


The using wire I mount it under the car where I wanted it
http://i918.photobucket.com/albums/a...n/100_6354.jpg


Now start by putting your line from the pump. Here is the first straight -6an fitting used. Run the hose down to under the car to the fuel filter.
http://i918.photobucket.com/albums/a...n/100_6358.jpg

and make a marking where to cut the hose to the fuel filter. Then make a cut
http://i918.photobucket.com/albums/a...n/100_6355.jpg


Now put your other end on
http://i918.photobucket.com/albums/a...n/100_6356.jpg

and now put your first half of the fuel line up and tighten it down. You will need -10an to -6an adapters if you use the same aeromotive fuel filter.
http://i918.photobucket.com/albums/a...n/100_6359.jpg

Then using the hose clamp I secured the hose down.
http://i918.photobucket.com/albums/a...n/100_6360.jpg

I decided to stop using stainless braided hose and bought russells black braided hose.


I started with the longest distance. So I began by adding a straight -6an fitting on the hose
http://i918.photobucket.com/albums/a...n/100_6468.jpg

and then connected it to my FPR. If you want to put your FPR where I did here is my FPR bracket DIY
http://forums.clubrsx.com/showthread.php?t=759243

So anyways, connect another straight -6an fitting to the hose and start from the bottom of the FPR which is the return
http://i918.photobucket.com/albums/a...n/100_6469.jpg


Then used clamps and started routing it down and around the header back over to the passenger side
http://i918.photobucket.com/albums/a...n/100_6518.jpg

http://i918.photobucket.com/albums/a...n/100_6471.jpg

and wrapped it behind some of the wiring harness. I also zip tied the fuel line every chance I could just ass added protection
http://i918.photobucket.com/albums/a...n/100_6472.jpg

Then I cut the stock feed line back where you can't see it and zip tied the return line to it all the way down the frame...
http://i918.photobucket.com/albums/a...n/100_6473.jpg

http://i918.photobucket.com/albums/a...n/100_6474.jpg

Then put the hose through up to the pump and measured and cut where needed
http://i918.photobucket.com/albums/a...n/100_6477.jpg

You also need to remove the quick release clip
http://i918.photobucket.com/albums/a...n/100_6476.jpg

I then clamped it down to the stock feed output. It fit extremely tight and I could barely get it on so I have faith.... also this is the return so it has a lot less pressure.
http://i918.photobucket.com/albums/a...n/100_6479.jpg


then I attached another AN fitting and started from where I had left off at the fuel filter
http://i918.photobucket.com/albums/a...n/100_6480.jpg


I then brought it up towards the transmission and moved it up towards the rail.
http://i918.photobucket.com/albums/a...n/100_6481.jpg

http://i918.photobucket.com/albums/a...n/100_6482.jpg


Now I put the rail on and fittings so I can mark where to cut the line. Now I make my mark on the hose and cut.
http://i918.photobucket.com/albums/a...n/100_6512.jpg

Because this is going to be seen I don’t want to scratch the fittings. So I blue tapped them
http://i918.photobucket.com/albums/a...n/100_6509.jpg

http://i918.photobucket.com/albums/a...n/100_6510.jpg

Now I attach the line to the first side of the rail.
http://i918.photobucket.com/albums/a...n/100_6517.jpg

and now I attach the FPR fitting and measure up the next cut
http://i918.photobucket.com/albums/a...n/100_6511.jpg

http://i918.photobucket.com/albums/a...n/100_6512.jpg


cut and add the fitting… almost done!
http://i918.photobucket.com/albums/a...n/100_6514.jpg

attach the line
http://i918.photobucket.com/albums/a...n/100_6516.jpg


BAM!!! Now you are done!
http://i918.photobucket.com/albums/a...n/100_6515.jpg




here is a small diagram
http://i918.photobucket.com/albums/a.../fuelsetup.jpg


**I probably missed some things and I’ll edit the thread if needed**

Great write up. I think I read on you CRSX thread that this was a pretty expensive DIY. Is it a must have when boosting, because I didnt put in a return line.

It all depends on your HP goals and your setup. I didn't have a return line before on my setup but this winter I decided to run one because I was going to swap to E85. All and all a full fuel setup will run a couple hundred dollars. The fittings are expensive, the line isn't cheap, and add filter, pump, rail, and FPR and you've hit $500+ without even trying....

I saw this one to before. and its a awesome DIY am planning on doing this.

What kind of HP range will you start to need a return? (i'm installing a MPx90 + intercooler, 1000cc, DW65 pump). If i do a fuel return I'll probably buy the AJP kit. Thanks for the awesome DIY!

This is way better than a kit. I suggest running a -8 an feed and use the factory hard line as return.

Quote:

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Originally Posted by easymovet

What kind of HP range will you start to need a return? (i'm installing a MPx90 + intercooler, 1000cc, DW65 pump). If i do a fuel return I'll probably buy the AJP kit. Thanks for the awesome DIY!

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Typically, you're limited at low to mid 400whp without a return with 1000cc injectors. That's what I've been told of the turbo guys. Rotrex may be different, but I'm not sure.

Quote:

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Originally Posted by Rbsjnh

This is way better than a kit. I suggest running a -8 an feed and use the factory hard line as return.

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Why? Easier?

Quote:

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Originally Posted by Rbsjnh

This is way better than a kit. I suggest running a -8 an feed and use the factory hard line as return.

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I don't suggest this at all... it defeats the purpose of the return line being the feed is so small. By running a larger return line you, for lack of better words, complete the fuel system loop... if you are going to pump a LOT of gas to the injectors using a -8an line feed you need to equally be able to return the flow of unused gas back with at least a -6an or else you'll just back up the pressure and defeat the purpose of your return line fuel system. Using a better return line will help relieve pressure from your fuel pump, keep more gas to it, and decrease injector duty cycle

Spaz, I am not suggesting using the -8an for the return, Im suggesting using the factory -6 an for the return

I ran -8 feed to -6 return. There was a guy making high 600's on -6 feed and -6 return. So the flow is there. Either way. But I wouldn't use the factory line as the return. It's a cheesy look to me and I don't see the performance being there.

Quote:

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Originally Posted by Si Speed 317

Typically, you're limited at low to mid 400whp without a return with 1000cc injectors. That's what I've been told of the turbo guys. Rotrex may be different, but I'm not sure.

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That HP range is probably true for turbo but the equivalent PSI range on a SC is probably more like 350whp. I think it's the pressure differential at the injectors (between the intake and the fuel line) that becomes the issue. Blurg I really don't want to drop another $600 but it's less that blowing the engine from a lean condition.

I'm not sure which kind of FPR to get, does this look right? FPR on amazon

Buy aeromotive nothing else

Aeromotive, copy that. There seems to be several types, bypass, efi... Spaz do you recall the model you have?

http://www.summitracing.com/parts/AEI-13101/

this is probably the best most used regulator on the market, fine for gas, e85 and race fuel.

that fuel lab regulator is a replica of an aeromotive.

I just have a AEM but if it doesn't work with the new setup I will be swapping it out with the Aeromotive for sure

I saw this kit for a fuel return system using the stock rail (for diffirent car, but same regulator) implemented by putting the FPR before the rail, any reason a similar setup wouldn't work on our cars, it seems to address goals 1 and 2? Not sure how much of an issue 3 is, and 4 seems to be in doubt.

1. keep fuel pressure rising 1:1 with boost so that the injectors don't have to stay open too long and atomization doesn't suffer.
2. better pump life since it's not pushing against a headed load, it also runs cooler with fuel flowing.
3. keep the fuel in the rail from overheating given the higher IAT of F/I engines.
4. Some have said injector #4 starts to starve and returning on the other side of the rail keeps equal flow to all the injectors.

The AGP kit description says that #4 is false, I'm going to try some experiments with water and hoses to see if this happens :) Otherwise this approach will save us buying a fuel rail.

^ I have no clue. Anyone else?

Here are some diagrams of what i'm thinking. I'm not exactly sure how the second inlet on the regulator works so it may be nessesary to use a T-fitting like the second diagram and cap off the extra inlet.

http://i.imgur.com/aKlk2.jpg

Quote:

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Originally Posted by easymovet

Here are some diagrams of what i'm thinking. I'm not exactly sure how the second inlet on the regulator works so it may be nessesary to use a T-fitting like the second diagram and cap off the extra inlet.

http://i.imgur.com/aKlk2.jpg

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Second one doesn't seem to be a good idea, I don't like the idea of a T fitting in a fuel line.

I dont like either diagram.

Tank-filter-rail-FPR-tank is how mine goes

Aeromotive seems to approve but does say that positioning the regulator after the rail is optimal.

Sent from my Galaxy Nexus using Tapatalk 2

placing it after the fuel rail gives the most fuel and highest pressures to the injectors at all time. Verse the fuel going threw the regulator then ending in a dead end at the fuel rail. So putting the regulator after the rail will keep a more constant flow past the injectors.

Quote:

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Originally Posted by Spaz

placing it after the fuel rail gives the most fuel and highest pressures to the injectors at all time. Verse the fuel going threw the regulator then ending in a dead end at the fuel rail. So putting the regulator after the rail will keep a more constant flow past the injectors.

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"You must spread some Reputation around before giving it to Spaz again."
Great info.