Help with fuel system design for LS1 install
 

[ Also posted this on LS1tech but looking for opinions from any possible source. ]

Trying to piece together the fuel system for the LS1 ('99 Z28 donor) that's going into my '72 Chevy shortbed. (This is my first fuel-injected project, so please be gentle with your advice and criticism.) Here's what I have so far:

• Custom gas tank with 3/8" NPT inlet and outlet
• Walbro 255 GSL392 external fuel pump
• WIX 33737 (Corvette) filter/FPR

I'm planning to do braided fuel line with AN fittings all the way from the fuel rail to the tank. I already know what fittings I need for the 'Vette filter/FPR and fuel pump. I need to know the following:

1. What size line should I be running throughout? I'm assuming AN-6 will be appropriate but I also know what happens when one makes assumptions.
2. What fitting(s) will I need at the fuel rail?
3. What is the proper layout from gas tank to fuel rail for the lines, filter, and fuel pump? My assumption (see disclaimer above) is that I will have the 'Vette filter with the inlet and return lines plumbed directly to the fuel tank, then line from the 'Vette filter outlet to the fuel pump, followed by another line up to the fuel rail. Is this correct?
4. The vendor for the custom gas tank says I need a 90° anti-siphon valve for the overflow fitting on top of the tank. The tank came with a 90° barbed fitting to go to a 3/8" hose, but that can be removed. What exactly should I have here? Searching for an anti-siphon valve via Google hasn't given me anything close to what I think I would need.
5. Am I missing anything?

Thanks in advance for the help. I have virtually no local resources and so I'm ordering everything online. Really want to make sure I get it right the first time and don't end up missing a fitting or buying stuff I don't need.

Thanks again,
Brent

Re: Help with fuel system design for LS1 install
 

Anyone have any thoughts on this? Truly don't mean to be impatient or demanding — just would like to get the parts I need ordered soon.

Re: Help with fuel system design for LS1 install
 

I realize this is an older post, but it looks like you don't have an answer yet, so......

Yes, -6 (3/8") with the exception of the return line from the filter/regulator to the tank, which is -4 (5/16")

IF you have a fuel rail that is a return-less system; that is, only one fuel line on the rail, then it should be a Russell #640850. It will look like this:
http://static.summitracing.com/globa...s-640850_w.jpg

Or you can use a Dorman #800121, like this (I would recommend threaded fittings however):
http://ecx.images-amazon.com/images/...500_AA200_.jpg

1] Return line from the tank to the Vette filter/regulator,

2] Feed line from the tank to the pump, then to the Vette filter/regulator,

3] Feed line from the Vette filter/regulator to the fuel rail.

In this setup, flow from tank to engine is right to left:

http://i191.photobucket.com/albums/z...-regulator.jpg

I am gonna take a guess here, is this suppose to be a vent tube that will allow air in, but not let fuel out? If so, many people on here have used these when doing Blazer tank swaps:

http://cgi.ebay.com/ebaymotors/Gas-F...=p4506.c0.m245
http://i14.ebayimg.com/02/i/001/33/13/1575_1.JPG

Re: Help with fuel system design for LS1 install
 

A little late, but good info nonetheless! (Already ordered everything and most of it's here; the rest will arrive Friday.) And thanks for the link to the eBay item. :)

My only question is whether I can use the -6 line for the return as well. The 5/16" return line connector goes to -6AN so I assume there won't be a problem. For a return line, I can't see why a bigger line would be a problem. (Too small, sure, but....)

Thanks again!

Re: Help with fuel system design for LS1 install
 

Yeah, my bad. In my application the OEM return is 5/16", so that's what rolled off my fingertips! -6 should do fine as well.

Re: Help with fuel system design for LS1 install
 

Hi, just starting my fuel lines tonight...how did you connect you lines to the gas tank "spouts"?

I bought the parts from Glock's fuel system list....just wondering though how you got the line started at the fuel tank / sender? (I've never used braided lines before)

So, do I:

1. cut the ends off the 3 fuel sender's tubes,
2. then put a nut on each fuel sender line,
3. then flared the fuel sender line with your 37' flaring tool,
4. then threaded your a/n end onto the nut?

I am running two fuel tanks if that helps too..

Thanks!!!

Thanks for your help!

Re: Help with fuel system design for LS1 install
 

So your question is: How do I attach AN hose to my trucks factory pickup/sending unit?

Or am I missing something?

What type of hose are you using? If you are using teflon SS hose you will not be able to clamp your hose to the sender. One option there would be to use a compression fitting to AN adapter. If you are using regular SS hose you can simply slip it on the pick up and clamp it. Hope this helps.

Re: Help with fuel system design for LS1 install
 

I need this dumbed down as much as possible; will the dorman 800121 and 800120 work for the fuel rails in a return style system using fuel injection clamps?
Posted via Mobile Device

Re: Help with fuel system design for LS1 install
 

No that's exactly it. I bought regular braided hose and all the A/N connectors that glock had listed in his build thread.

I'm trying to find a piece-by-piece order of what to do but searching the board and even google just gives a hodge-podge of information that is only half there, if that.

Any information, especially how to join the braided line to the fuel sender as shown in my pic attached would help! Thanks!!

Re: Help with fuel system design for LS1 install
 

YES they will, I was using this until I found out that certain drag strips may have an issue with the rubber line. It was brought up that NHRA does not allow more than a total of 12" of rubber in a fuel system setup. I switched all mine to braided hose.

http://i112.photobucket.com/albums/n...y/DSCN0002.jpg
http://i112.photobucket.com/albums/n...y/DSCN0001.jpg

Re: Help with fuel system design for LS1 install
 

Awesome! I will order them up. I have no intention of going down the track and really, I barely drive it. Thanks!
Posted via Mobile Device

Re: Help with fuel system design for LS1 install
 

X2 I used a 800120 on my return line.

Ignore the rust please:lol:

http://i104.photobucket.com/albums/m...y/P1060310.jpg

Re: Help with fuel system design for LS1 install
 

these pics need to be in the FAQ fueling section....

Re: Help with fuel system design for LS1 install
 

You can see and read about what I ended up doing about halfway down page 12 in my build thread, starting at post 292 (link). Here are a few pics from that thread:


http://67-72chevytrucks.com/vboard/a...1&d=1249258630

http://67-72chevytrucks.com/vboard/a...1&d=1249258630

http://67-72chevytrucks.com/vboard/a...1&d=1249258630

http://67-72chevytrucks.com/vboard/a...1&d=1249747822

http://67-72chevytrucks.com/vboard/a...1&d=1249747822

Re: Help with fuel system design for LS1 install
 

This info helped a lot. Thanks guys

Re: Help with fuel system design for LS1 install
 

In the picture of the sending unit, what does the pipe in the middle of the sending unit do?

Re: Help with fuel system design for LS1 install
 

I agree this needs to be a FAQ section. With part numbers of what everyone is using for their builds.

Re: Help with fuel system design for LS1 install
 

i have all of my part numbers on the reciepts around here somewhere from my build. i can dig them up if needed.

Re: Help with fuel system design for LS1 install
 

I'll add this thread to the LS FAQ.

http://i104.photobucket.com/albums/m...y/P1060304.jpg

Re: Help with fuel system design for LS1 install
 

How do you connect to the regulator with hard line?

Re: Help with fuel system design for LS1 install
 

Possible dumb question here, but....

If there is a fuel line and return line coming from the rails to the regulator, but there is only one "input" on the regulator, then two out (one to pump and one to return in tank), where does the return line from the fuel rail go???

Does the two lines coming from the rails need to "join" before the regulator??

First LS Swap obviously... :uhmk:

Re: Help with fuel system design for LS1 install
 

What year is your engine? Sounds like you have the return style fuel rail. This style has the fuel regulator built into the fuel rail. The corvette regulator is not needed for this style. The two lines from the rail just go straight back. One to the pump (either internal or external) and the other line is the return that goes to the tank.

Re: Help with fuel system design for LS1 install
 

It's a 5.3 out of an 03 Tahoe. Has two lines right off of the intake.

So no need for a regulator? I don't remember seeing any kind of regulator in the system?? What should the rails looks like?

That would be good news, could be why I'm confused about this fuel system layout lol

Re: Help with fuel system design for LS1 install
 

Two lines off the intake or two lines off the fuel rail? , Is the second line going to the purge solenoid by chance? Can you post a pic of what you have? Be able to give you better advice that way.
Posted via Mobile Device

Re: Help with fuel system design for LS1 install
 

Hey folks,

I'll jump in with a question also. I am finishing my budget for my LS1 swap and I'd like some advice.

I am running an LS1 our of an 02' F body, which I believe is the "returnless" style rail. I am buying a tank with an intake Aeromotive stealth efi pump from Boyd's. My plan is to run the feed and return lines from the tank to Vette regulator, and then a single feed line to the LS1 rail. I plan on using all braided hose for simplicity of install.

Approx how many feet of line did you need? I dont have the motor yet so I cant measure. Im just doing this to finalize the spreadsheet

Would this kit be a good idea, along with an extra few feet (4-5?) of -4 AN line for the return + extra straight/90* fittings? I know I will need extra -6AN fittings and clamps.
http://www.summitracing.com/parts/SUM-PUMPKIT1/

I've never messed with fuel plumbing other than carbed stuff. Braided line/fittings are new to me.