hey gents I am in need of some assistance/advice

I did an ls swap in my obs I originally went with a carb set up. it was easier and cheaper at the time. now I am in the process of switching back to a fuel injected set up.

I have the pump figured out(walbro 255). do the engines run consistently on 58psi? I notice on both the intakes I have there is a vacuum port on the return style rail

what year trucks come with the return less fuel rails? I have an 02 intake that has the return rails and an 05 that has return style as well.

the truck was set up with a fpr near where the rails should be. would it be a problem running it as a dead head system on the return less system. as the regulator and lines are already mounted on the firewall from the previous set up and changing the line routing is not really optimal.

anyone have a return less fuel rail they want to part with as well.

 

All years have a 58psi base pressure.

The 99-03 run a return system with a referenced regulator on the rail.

The 04-07 run a returnless system with a non-referenced regulator in the tank with the pump. The 07+ use a FPCM controlled fuel pump in addition to the regulator in the tank.

The years might be different for SUVs, vans, and 2500s, but the above is true for the 1500s.

You can do it either way, but your PCM needs to know which you decide on.

 

hey thanks that is some good information there.

now for a guy that is kinda new to this stuff. what exactly has to be changed or done in the pcm?

I had nelson performance program the ecu for a 2002 set up 6.0l. the harness does have a relay and such for the fuel pump. so would the computer send different voltages to the fuel pump?

 

now you also mentioned the referenced regulator. is this to keep the pressure stable at all rpm loads? or does it pull fuel at say idle and increase fuel pressure at wot?

 

A referenced regulator will keep pressure across the injector constant, so when you are at anything but WOT there is idle in the intake sucking on the injector so the regulator will reduce pressure so the pressure difference across the injector stays the same. This means your injector flow rate table in the tune is a constant value.

A system with a non-referenced regulator will have an IFR table that changes with slightly higher flow rates under engine vacuum.

 

How would the returnless system work if the vacuum port was not hooked up on the rails

I do have a aeromotive 1:1 regulator would hooking up the reference line on the regulator accomplish the same as hooking the vacuum line on the stock rails?

 

The second part of your question, yes that is correct.

The first part I tihnk you meant return instead of returnless, in that case if you didnt have a reference for a return system it would act like a returnless system.


But keep in mind they are really two different things we are talking about.
Referenced or non-referenced is indepent of rather its return or "returnless". Returnless is actually a bad name for it because there is a return but its inside the tank so you dont see it. Return systems are typically referenced (but not always), and returnless systems are typically not referenced (but not always).

You could run a referenced returnless system if you ran a vacuum line from the tank to the intake, but thats a little silly.

 

thanks for all the info.

it looks like i will just extend the feed line. swap to an aftermarket rail. then put my regulator after the rails. dumping back to the tank then hook up the refernce line to my regulator. this seems this simplest way except having top swap up the rails.