replacing my fuel pressure regulator

BlackVert · Oct 13, 2004

my fuel pressure regulator is bad. i got a replacement one, and i was hoping someone could point me to a "step by step" procedure for installing it, or fill in the missing steps in this one?

1. disconnect the battery
2. take off vacuum hose
3. remove bolts securing the fpr
4. take off old fpr
5. put new fpr on
6. replace bolts
7. replace vacuum hose
8. reconnect the battery

do i need new o-rings or gasgets or anything like that?

any other "gotchas" i should know about?

cobra259 · Oct 13, 2004

You should have new seals on the new reg. You need to releave fuel presure. Take the cap off the valve on the fuel rail. You will see a schrader valve (just like a tire valve) you need a small screw driver,press the valve,MAKE SURE you cover it with a rag, as gas WILL spray out!! Also take off the gas cap,that will help releave presure as well. The rest is just like you said.

willys1 · Oct 13, 2004

Take the throttle body off,it will make the job alot easier Its very tight back there!!//You will need new gaskets for the TB when putting it back on.If you have the money,you should put a 65mm TB on while your there

go-stang5.0 · Oct 13, 2004

You dont need to remove the TB its just a hassle and a waste of time. If you have small hands you will be fine. Also, if you dont wanna make a gassy mess....just let the car sit for about 4-5 hrs. The fuel pressure would have subsided by then so you wont have to put a rag around the schrader valve and let it out. Just make sure you dont pressurise the system as any time in that 4 hrs. (ie. turning the ignition on) or you will be in for a big surprise.

TrueBlue95GT · Oct 13, 2004

Or you can go the easiest way to release fuel pressure which is turn on the car and let it run, pop the trunk, disconnect the fuel inertia switch and let the car run until it runs out of fuel. Then you should still have a little residual fuel in the fuel rails, so put a rag under the regulator when you take it off, but it shouldnt be much.

willys1 · Oct 13, 2004

I just changed my Fuel filter,it took 45-60 minutes,and there was no Fuel pressure.It makes the job a hell of alot easier.but yeah if you have small hands.

BlackVert · Oct 13, 2004

cobra259 said:
You should have new seals on the new reg. You need to releave fuel presure. Take the cap off the valve on the fuel rail. You will see a schrader valve (just like a tire valve) you need a small screw driver,press the valve,MAKE SURE you cover it with a rag, as gas WILL spray out!! Also take off the gas cap,that will help releave presure as well. The rest is just like you said.

the one i got is a used one from a car that had 35,000 miles on it when the fpr was taken off. do i still need new seals? is it two o-rings?

BlackVert · Oct 13, 2004

willys1 said:
Take the throttle body off,it will make the job alot easier Its very tight back there!!//You will need new gaskets for the TB when putting it back on.If you have the money,you should put a 65mm TB on while your there

i actually just got a 70mm BBK t/b. i think i'll do that at the same time ...

BlackVert · Oct 13, 2004

go-stang5.0 said:
You dont need to remove the TB its just a hassle and a waste of time. If you have small hands you will be fine. Also, if you dont wanna make a gassy mess....just let the car sit for about 4-5 hrs. The fuel pressure would have subsided by then so you wont have to put a rag around the schrader valve and let it out. Just make sure you dont pressurise the system as any time in that 4 hrs. (ie. turning the ignition on) or you will be in for a big surprise.

great idea! i'll take a late lunch break and do it in the parking lot at work. then it will have sat for 5 hours and the fuel pressure should be gone. i'll cover it anyway with a rag just in case tho ...

Silver85TC · Oct 13, 2004

willys1 said:
I just changed my Fuel filter,it took 45-60 minutes,and there was no Fuel pressure.It makes the job a hell of alot easier.but yeah if you have small hands.

The fox stang's have a different intake TB design than the 94/95's. I agree on the Fox stang's that it would be easier if you removed the TB. On the 94/95's, the intake opening is bent, so its not in the way for accessing the FPR. Also, the screw heads are on bottom on the fox's making them a bi*ch to get at without loosening the fuel rail. On the 94/95's, the screw heads are on the top making it literally a 5 min job to change.

Hope that helps

cobra259 · Oct 14, 2004

As long as the o-rings look like they are in good shape,go ahead. You will know REAL quick if they are leaking!

BlackVert · Oct 17, 2004

In the pictures, where does the unattached o-ring go?

BlackVert · Oct 17, 2004

please guys, i'm hoping to replace this tomorrow during my lunch break.

94TURBO5 O · Oct 17, 2004

It goes on the larger nipple on the bottom pic. It's what goes into the fuel rail and acts as the gasket.

BlackVert · Oct 18, 2004

94SC50 said:
It goes on the larger nipple on the bottom pic. It's what goes into the fuel rail and acts as the gasket.

great, thanks. i hope it doesn't leak ... it will be great to finaly get this behind me so i can get on with my tuning.

94TURBO5 O · Oct 18, 2004

Are you putting back on the stocker in the pic?

BlackVert · Oct 18, 2004

yes, i am going back to stock for a couple of reasons:

1- my current one is bad and i am very tight money-wise right now
2- i have no idea what the guy before me had the fuel pressure set to and i don't want to have to spend $30 for a gauge
3- the high/low slopes for stock injectors are well known at the stock fuel pressure
4- i need to nail my injector slopes before installing this 80mm mass air meter i have had sitting around for the last 1 1/2 years.
5- i am nowhere close to flowing enough air to warrant larger injectors or more fuel pressure

final5-0 · Oct 18, 2004

Black96VertGT said:
yes, i am going back to stock for a couple of reasons:

1- my current one is bad and i am very tight money-wise right now
2- i have no idea what the guy before me had the fuel pressure set to and i don't want to have to spend $30 for a gauge
3- the high/low slopes for stock injectors are well known at the stock fuel pressure
4- i need to nail my injector slopes before installing this 80mm mass air meter i have had sitting around for the last 1 1/2 years.
5- i am nowhere close to flowing enough air to warrant larger injectors or more fuel pressure

Over a period of time I've come to these thoughts about fuel pressure.

As you stated in item 3, you start to tune your adaptive strategy at stock fuel pressure by making adjustments to the inj values of high/low slopes, breakpoint, min pw, and offsets.

This is a deal of make a change and drive while datalogging to see the results. It can take a good bit of time to get your inj's dialed in. After a few bolt on's, even the stock 19# inj's can benefit from some tweecing.

If you change the fuel pressure all of your work of dialing in the inj values to the point that the adaptive strategy is only making small changes in CL will become null and void.

All of the pcm's fuel strategy is based on stock fuel pressure. With a tuning device you have access to all of the pcm's fuel tables which will allow a + or -change at various loads & rpm's. This is a more accurate method of fuel adjustment than mechanical.

IMHO, an afpr can be counter productive to someone who has a tuning device and is no longer needed.

Later
Grady

BlackVert · Oct 18, 2004

final5-0 said:
...
If you change the fuel pressure all of your work of dialing in the inj values to the point that the adaptive strategy is only making small changes in CL will become null and void.
...

exactly. that is why i have to basically start al over and get the slopes right before installing the 80mm mass air meter housing. that is why i re-installed my stock mass air meter over the weekend. now i have a maf transfer curve i know is accurate, so i can dial in the injectors. once i get the slopes, breakpoint, and offsets right, then i can install the 80mm meter and dial that in. then i can put in the 70mm t/b and dial that in. then i will finally be able to get to the timing and maybe i'll start feeling some gains from the heads and intake ...

- chris

final5-0 · Oct 18, 2004

Black96VertGT said:
exactly. that is why i have to basically start al over and get the slopes right before installing the 80mm mass air meter housing. that is why i re-installed my stock mass air meter over the weekend. now i have a maf transfer curve i know is accurate, so i can dial in the injectors. once i get the slopes, breakpoint, and offsets right, then i can install the 80mm meter and dial that in. then i can put in the 70mm t/b and dial that in. then i will finally be able to get to the timing and maybe i'll start feeling some gains from the heads and intake ...

- chris

Chris

Maybe I can save you some work with some things I've been through.

I saw the kamrf/pulsewidth curve change when I made a mod to my home made cai.

The original setup was a straight shot to the fender hole and a 90 bend down to the maf/filter. The new setup was the doing away of the 90 bend and making the fender hole just large enough to put the maf/filter in the fender.

I saw the k/pw curve change when I went from the stock tb to the 65mm tb.

I saw the K/pw curve change BIG TIME when I went from the stock maf to the ProM shorty 80 caled for 30's.

I guess I'm trying to say that any change to the airflow from filter to intake is gonna mess up your efforts of dialing in the inj's.

IMHO, I would just put the new maf on and load in the values given by ProM for it's curve. I would also have the 70 throttle body and cai or whatever you are gonna use in place for final inj dial in tuning.

If you can't get all of those parts together at the same time for the final inj dial in I would just tweec the inj values close enough that the adaptive strategy will put your K's to the point of reasonable drivability and idle.

To dial in the inj's is a time consuming kinda thing which you know all too well.

Why do it over and over with each change

Just do it once

Hope that helps

Later
Grady

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