Fuel pressure regulator help
 

I got my ls rx8 up and running. Starts up fine. But after it starts runs a little weird. So I checked the fuel pressure and sure enough. Way to much fuel. I have the corvette style filter regulator hooked up which is supposed to drop the psi down to 58. But I'm getting around 70 to 75psi at the rail. Probably because the pump is 320lph. So I'm thinking about ripping off the corvette style regulator and putting a aftermarket fuel pressure regulator on it. I'm thinking of the ways I could do this and would like some input from couple people on how it might work best or even a different way I'm not thinking of. Below are my 3 examples. Let me know which one would work best. Would like to only have 1 line under hood so thinking first one. But not sure if that would work. Let me know please. Also if someone needs this corvette style regulator filter. I don't need it so maybe like 5 bucks and shipping and it's yours. Only been on for maybe 2 months and started 10 times or so. Let me know what you guys think on how I should do this.

https://cimg5.ibsrv.net/gimg/www.rx8...c8b4fc5162.jpg

1st way

https://cimg6.ibsrv.net/gimg/www.rx8...33370d4578.jpg

2nd way

https://cimg7.ibsrv.net/gimg/www.rx8...e11fb81e54.jpg

3rd way

just 3 quick diagrams to show different ways that I think it could work.
never had a aftermarket fuel pressure regulator , so I'm not sure on how the setup is done. relay hoping on the first pic. cause that would allow me to only have 1 line in the engine bay. I would just throw a an6 y where the corvette style regulator/ filter is now and keep one line from there up to the regulator in the engine bay. just not sure if that would work the way I'm thinking it would or if it wouldn't work at all. but please let me know . I need to get the pressure down to around 50 to 60 psi at the rail.

I always opt to using the third style you posted there.

Your 320LPH fuel pump is definitely overwhelming your Corvette Filter/Reg, It cannot regulate that much fuel through it, I had this exact problem with my last setup, and now I am using a billet regulator for this reason.

Good luck!

First two setups won't work, path of least resistance will dump your fuel into the Y and right back out, causing either no fuel for your regulator or an inconsistent supply.


My system goes much like your third option. Its been a while, so I will double check when I get home, but.....


From pump side filter it goes regulator, out of regulator into the rear side of the passenger rail, front side of passenger rail crosses over to the front side of the drivers rail, and then from the drivers rail to the return on the fuel cell.


I junked my stock fuel system for many reasons, but one of the biggest is I do not like deadheaded fuel systems.

you can put the regulator at the tank end..with a short return...and run the supply line to the fuel rails as a dead end system as well.....basically what the stock system does

That will give you the regulated pressure without running a line all the way to the front. Problem with that though if you are FI you need to run a reference pressure line to the regulator anyway

I mounted my regulator in the engine bay and ran a separate -6AN line for the supply...and used the stock line as the fuel return. That way is good for 500HP at least before you need to worry about bigger lines

Very true, I ran that setup as well and had good luck with it....although iirc the regulator is more consistent closer to the motor?

I like the regulator at the engine end .....there is faster response to the pressure reference. The large line goes to the fuel rail.....so there is more fuel with less pressure fluctuations. When you are at stock fuel requirements I don't think it matters at all.....just when you are pushing a lot more fuel through

With that setup you would definitely be good to go with some good breathing room, your injectors will limit you first. The LS1 had 28lb, a few years had 26lbs...my 6.0 had 24s stock haha.