shawnk

I just completed the fuel presssure regulator (1:1) install and my pressure at idle is only 30 psi. I thought I read somewhere that it should be adjusted to 40 psi. But mine only adjusts between 22 (bolt all the way loosened) and 30 (bolt about 2/3 of the way in - tightening further does nothing). Is this right? Am I going to run lean? It is installed on the intake side and I do still have the stock pressure regulator on the return. I have upgraded to the hi flow denso pump and replaced the filter. If I want as much fuel to get to the rail until I get it dyno-tuned on Friday do I loosen or tighten all the way?

Thanks for the info!
Shawn

shawnk

Ok. So I just read in the manual that the pressure with just the stock regulator should be 28-32 psi. So it seems that I am where I need to be but the nagging question since I started this project has come to my mind again and I guess I'll just throw it on out and see if someone can enlighten me. None of the how-to's that I read even mentioned removing the second rail/stock regulator. I have seen a few posts on the forum hinting that some people do tap the second rail and remove it. But I did not (yet)... But if the regulator on the return lets go at 30 psi (at idle) then no matter what the new regulator lets in to the rail it will not be able to build pressure higher than 30.

And if that is the case why would I need the regulator on the intake side?

Shawn

Wargasm

Exactly...

You shouldn't have two regulators like this. What I would do is take off the secondary rail and remove the stock FPR.

Then buy the appropriate connections/hoses/whatever to connect the hole that you just created to your new FPR and have that be the very last item before fuel returns to the tank.

Setting the pressure at about 30 at idle or about 40 with the engine off but with the circuit opening relay in the diag box jumpered will give you about the right pressures to emulate the stock setup. If you want more pressure, you can adjust up from there.

What's wrong with the stock FPR anyhow?

Brian

shawnk

Well that is what I was thinking... I go to the tuner tomorrow and I wont be able to do that since I don't have a 1/4 NPT to 6 AN connector to tap in (and they are not available locally) so it looks like I just did a very expensive PD replacement/modification. Good news is that my PD was leaking and at least I have gotten that out of the engine (permanently) and now I have a pressure gauge in the engine bay to keep an eye on. I did a pressure regulator because that is what everyone said to do (for my single turbo conversion) and I didnt really know too much about this car when I bought this "fixer up" and I bought all the parts at the beginning of this project. One question though - if you put this aftermarket regulator in after the rails then how do you plumb it? Do you block off one of the 10AN inlets? In the short term should I just crank down the screw to make sure that this regulator is not limiting my fuel? I am looking to get 350-375 HP and I have 550/1300's does the stock regulator let me get there?

Shawn

Marcel Burkett

Yes you would need to block off one of the return ports (unused) , also you need to check out how you wired the replacemrnt pump , If you have conected it to your factory circuit , there would be the fuel pump resistor which would drop the supply voltage at low load and idle causing the pump to slow down , hence your low idle pressure . If you run the car with the regulator adjusted all the way in you would most likely run very rich , you should remove the reference line from the regulator allowing it to "zero" off at atmospheric pressure , then make the adjustments to the regulator .
most people bypass the resistor ,or run a direct from the battery (through a relay ) and remove the stock regulator and simplify things.

10sec rx7

Dude, take the reg off the intake side of your fuel rails, it should always go after the fuel rails otherwise you will not get pressure to the injectors.

Directfreak

iTrader: (2)

http://fc3s-pro.com/TECH/MODS/FUEL/fpr.htm

Wargasm

Just another FYI, don't tap into the hose to the MAP sensor to get your boost compensation for the FPR. This can mess up the signal to the map sensor somewhat. Dave figured this out with me at KDRotary yesterday when we were tuning my car.

Brian