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Ive got an 03 5.3 lsx in My 85 foxbody mustang with on3 7875 turbo and it has the stock truck intake with returnless fuel rail with 3/8 pushlok feed line and fuel lab afpr at the rear of the car. I'm looking to upgrade the fuel pump to a magnafuel 4303 So I can make the switch over to e85 and was wondering what feed and return to use with the stock truck rail? Or is it even feasible?
I use the magnafuel pump with E85 feeding my stock ls3 rails. It will work just remove the Schrader valve from the test port and run a fuel line from there to a fuel regulator. Then run the return line from the return port to the fuel tank. May have to ditch your current regulator and go a different route tho.
i did a 044 from my stock fairmont tank, into a 55 dollar regulator from squeeze performance, then fed the stock LS1 returnless rail like this, made 700whp thru an 80e
Denmah that is the exact way its setup now with 3/8 pushlok but the fuel lab regulator is at the rer bumper. it is a 1/1 regular but the vacuum port is not hooked up right now. I have not purchased the 4303 yet. I have 80lb
SD injectors with a single walbro 255 in the tank right now on pump 91. Looking to max out the 7875 on e85 probably around 20psi
Doing high boost like that I would recommend going to a boost referenced regulator for sure. I'm sure the way you have it setup will work, I've just always ran my regulator after the rails. It's a personal preference type thing and people have had success doing it both ways!
How about this setup. I would do dual walbro's in the tank but the hole is to small to fit them in. The Fuel lab fuel pressure regulator is 1/1 boost referenced. Just dont have a vacuum line hooked up at this time. I figure the tee in the system should flow more than going through the regulator.
This would be pretty easy to setup with different style pumps. If you move the regulator to directly off the rail, the current feed line could be reused and would only require a new return line. Then all that would be left is the section from the tank to the fuel filter, which could be setup with a single intake walbro 430 or sump it and run the 4303.
Something wrong with running the regulator at the back of the car?
No, though it makes adjustments more difficult. I run the 4303 on the OEM LS1 rail (no return). Works just fine. 1/2 supply, 1/2 return. Lots of street driving as well.
Mine is setup just like this, same regulator and all. The car pictured made over 850whp on e85 with this setup. And thats a -6 going to the rail. Total FP was in the 96psi range though. (3 255hp walbros) I think the dead headed setups tend to perform better with additional pressure.
I'm going to move the regulator up front and use the current -6 feed as the new return and run a new -10 feed from the magnafuel 4303
Originally Posted by LT1RAY
This would be pretty easy to setup with different style pumps. If you move the regulator to directly off the rail, the current feed line could be reused and would only require a new return line. Then all that would be left is the section from the tank to the fuel filter, which could be setup with a single intake walbro 430 or sump it and run the 4303.
Cool thanks for the tip on the rubber isolators. I'll just weld a -10 bung on the tank. It's already got a -6 bung for the return. And I'll turn the old pump pickup into a couple vents.
I can get a weld on sump for $50 and weld it on but on the foxbody by the time the sump is welded on its so low you really have to mount the pump super low
02-21-2015, 11:19 AM
Magnafuel 4303 to stock truck rail??? 
