so I was doing some thinking and was wondering which setup has had best results. Running the regulator on the return line? Or run the regulator on the feed line and cap the return on the tbi?

 

Interesting question. I'm going to tune into this as well.

I was going to try the second methond a few years ago but never got around to doing the project.

 

The FPR needs to be plumbed into the return line.

Running a TBI off of the end of a FPR is a disaster. The air and fuel vapors won't get purged back to the tank. They end up being purged out the injectors instead of fuel.

RBob.

 

I just want to clarify- the regulator on the feed line will have a return, or does that not matter?

I've been working around a few ls1's and srt's. I noticed the setups are plumbed that way.

 

Yes, even with the regulator having a return line, you do not want to dead end the TBI.

The reason GM gets away with a return less system on the LS1's is mostly the fuel pressure. IIRC, it runs in the 58 to 60 psi range. Plus the design of the FPR and fuel delivery takes air separation into account.

Vapor issues with stock TBI systems is why GM went to 30 psi on the '94 & '95 BBC trucks. And the HD trucks got 20-second key-on fuel modules for prior years.

RBob.

 

awesome, thank you sir!

 

Good info and an explanation that makes sense as well. I know next time I need to have adjustable fuel pressure on a TBI how I'm going to do it. And a cheap dead-head style regulator on the return line is many bucks cheaper and easier to install than a return-style regulator to boot!