Ok, so I've seen this question pop up a lot, and as much as I love to repeat myself, I've decided to make an official thread and then link to it in the stickies so that....well I don't have to keep repeating myself!

First off, I'm going to give some general info on fuel pressure regulators. Then I'll give a step-by-step on how to set the fuel pressure. If this sounds weird it's because I'm copying and pasting from an email I just wrote.

Althought just about any FPR can be made to work the SR NISMO one is the easiest. The PN is; 22670-RR580 and looks like this;You will have to use a longer peice of hose as the angle on the outlet is wrong and you will have to loop it around to make it work. Many of us have been running them like this for years with out a problem.

In answer to your questions, no, the stock FPR isn't a rising rate, and you don't want a rising rate. They use rising rate FPR's on NA cars that have been converted to forced induction (turbo/supercharger). Since our ECU already has all of the info it needs to add the correct amount of fuel based on the input it's receiving from it's various sensors, all you need to do is give the fuel injectors 36psi static pressure and everything should be OK. If you use a rising rate FPR, your AFR's will get horribly rich as boost pressure increases. As for the 90° hardline, yea, you can remove it.

Static fuel pressure is the fuel pressure that is in the rail relative to the vac/pressure in the manifold. The purpose of a fuel pressure regulator is to give the injectors a relatively constant amount of fuel pressure so that the ECU is easier to program. Here is what I mean; under vacuum, with out a fuel pressure regulator, MORE fuel would be injected than normal since the manifold is "sucking" the fuel into the rail. To compensate for this, the FPR drops the pressure in the rail so that not as much fuel is available to be injectors. The opposite happens under boost. The pressure in the manifold pushes back on the fuel trying to come out of the injectors. With out a fuel pressure regulator, you would have to keep the injectors open longer, or use bigger injectors, which can make having a smooth idle difficult. With the FPR installed, when the boost pressure in the manifold increases the regulator increases the pressure in the fuel rail in a linear proportion so that the same relative amount of fuel is injected. AKA, with vac fuel pressure goes down, with boost, fuel pressure goes up.

It is nearly impossible to set static fuel pressure with the motor running, so don't bother trying. Here is how I do it;

Install new fuel pump

Install fuel pressure regulator

Install fuel pressure gage. It needs to come after the fuel filter, but before the fuel pressure regulator. Right after the fuel filter is the easiest.

Remove cover over fuse/relay behind the battery

Find the fuel pump relay. On my car it's green. Look at the diagram on the top of the cover to determine which relay is the correct one

There are two tabs holding it in. Depress the tabs and pull up on the relay. It should come out

You will now see 4 female spade connectors. 2 are close together and 2 are farther apart. It looks kinda like this;



Build a jumper wire. This is simply a short piece of wire with both ends stripped. Make sure it is of a decent gauge as the fuel pump pulls a moderate amount of amps

Insert the jumper wire into the 2 spade connectors close to each other

Turn on the ignition. DON'T START THE CAR! The fuel pump should come on and stay on

Using the adjustment on the fuel pressure regulator, set the fuel pressure to 36psi via the needle on your fuel pressure gauge

Turn off the ignition, remove jumper, reinstall the relay and cover, and start the car.

The fuel pressure at idle should be LESS than 36psi. When you are in boost it will be MORE than 36psi. If you've installed the gauge under the hood like I have, you won't be able to read it, but that's not a big deal as long as you've got a Lambda/AFR gauge.

Enjoy your properly fueled car!

thanks this was most helpfulwhat advantages does a Lambda/AFR have over a normal wideband, is there a difference or is it simmply another way of displaying the same info

float_6969 wrote:In answer to your questions, no, the stock FPR isn't a rising rate, and you don't want a rising rate. They use rising rate FPR's on NA cars that have been converted to forced induction (turbo/supercharger). Since our ECU already has all of the info it needs to add the correct amount of fuel based on the input it's receiving from it's various sensors, all you need to do is give the fuel injectors 36psi static pressure and everything should be OK. If you use a rising rate FPR, your AFR's will get horribly rich as boost pressure increases.

I don't mean to nit-pick, but I believe that the Nismo Adjustable FPR Type-A is rising rate, 1:1 to be exact. That is the reason that there is a vacuum hose fitting on the regulator.

EDIT: Replying to a 3 year old post, noob is me.

I explained what the difference between a rising rate and a fixed rate FPR is in that post. A 1:1 is NOT a rising rate FPR. A 2:1, or 3:1 would be a rising rate. 1:1 simply means that 1 psi of manifold pressure equals 1psi increase of fuel rail pressure. Obviously this isn't a rising rate, this is a fixed rate. And example of a rising rate FPR would be if a 1psi increase in manifold pressure equaled a 2psi increase in fuel rail pressure.

Does that make more sense?

And to further re-enforce my point;http://images.google.com/imgre...m%3D1

Ryan, this may help people too. This is how to properly install an adjustable fuel pressure regulator.

thanks on your diy step by step fuel pressure post

any tips on actually installing the nismo FPR...

Edit: NVM found it... http://www.driftopia.com/2007/...r-fpr/

or a link to thread...i thoguht i saw one long ago...but that comp died... -_-;

tip : Fuel pressure hose is 5/16'' incase anyone needed to know...i did...lol
Modified by DALAZ_68 at 9:33 AM 12/28/2009

any other info will be appreciated...?

what other info do you wish to know?

i know the location, i know its held on by two screws...

but i need some info on how to actually physically remove it... what are the easiest access point, over the manifold, under the manifold?

do i have to remove the manifold itself?

i pretty much need a walk on it, but my searching skills on this topic suck... :-(

and im running on 2 hours sleep for the last 2 days...

first..get some sleep.

then remove the IACV, then the whole fuel rail and change it out that way. its the easiest way i've found.

and that ^

is exactly what i will do...im assuming i should change out the O-rings while im at it...?

DALAZ_68 wrote:and that ^

is exactly what i will do...im assuming i should change out the O-rings while im at it...?

Definitely do this, such a smart thing to do while your in there. I hate injector o-rings.

i didn't change my o-rings, but it would be good practice.

any time you change your regulator, injectors, filter, etc... I would ALWAYS put new o-rings, hoses and clamps on for piece of mind... its cheap insurance that you wont have a leak, or worse... A FIRE.

MeanGreenS13 wrote: A FIRE.

err,,,kinda how i lost the SOHC...

14v will create more pressure. Why have the pump run at 12.Xv?

when the alternator is running, it should be at about 13.8-14.5v. Walbro fuel pumps pump more fuel at those voltages instead of the car not running and only powering the fuel pump at 12.X volts. Also, as the car idles injectors are absorbing some of the fuel pressure by releasing.

When injectors are tested they run ex. precision 43.5 or 50 psi not closed but open it has 50 psi when closed it probably spikes to 58psi closed at 1000cc's. This is what i was told.

but, then again you can't always believe what you hear.
Modified by warren540 at 2:32 PM 3/5/2010

Sorry this is an old post and I am new to this forum. But I need to ask this.
I installed this FPR and I set it perfectly but over time (a week or so) the pressure rose. I tried to adjust it back down but it won't go below 40-42 psi and I am a bit worried about this. Anyone have any idea regarding this?

Cheers!

kinked return line?

thanks man I will look into it. I replaced the old line but it might be that it is just a bit short and with all the angles going on there it is being restricted slightly

I have a big loop in mine so it's not kinked.

Hi there, this is regarding your adjustable fpr post, I had one of my fuel lines on the fpr crack and leak, during removal I damaged the fpr, luckily had a nismo adjustable fpr, but am unsure how to go about adjusting the correct flow,.. Is that something you would have to have a shop do? Vg30de.. Z32. Sorry for any redundancy.

Procedure is similar to above, but I don't know where the relay is at on the Z and I don't know what the base fuel pressure is on the Z. I would suggest posting a question about how to set the fuel pressure in the correct sub forum;
vg30-ve30-forum.html
or
z-series-general-forums.html

Thanx dood!

Can I just buy a gauge on ebay? I have an fpr from an sr but I don't have a gauge...

You need to make sure it's an actual fuel pressure gauge. Other than that, you're fine. If you're getting a cheap gauge, I wouldn't leave it hooked up though. I would hate to see you have an engine fire because a cheap gauge leaked fuel all over.

when replacing the FPR, I also recommend replacing the crappy philips head screws with bolts for easier removal/installation... I recommend flange head bolts, but they are hard to find in those tiny sizes... I believe the thread size is M5x0.8 or maybe M4x0.8... I don't remember... it's been years since I messed with this

use loctite purple (hard to find) or lock washers with the bolts