Domestic513

I need to know if it is worth it to take your car apart and fix the stock fuel pressure regulator or if it is even fixable? What i mean is I hooked up a fuel pressure guage and I wasnt getting and fuel when I tried to boost, so my fpr is either broken or just the line fell off of it. So just get an aftermarket one or just see if you I can fix the stock one?

Dougie_fresh_007

aftermarked its not that expensive and u have alot of advantages like higher pressure

twokrx7

iTrader: (1)

Simply no reason to go aftermarket unless you are going really serious on horsepower and high boost. Stock fpr is good up to 20+ psi, why bother?

rynberg

I just had my fuel pressure regulator replaced as the diaphragm was leaking fuel back down the vacuum tube to the intake plenum.....you want to talk running rich! I don't think there's much you can do in the way of fixing it. If you examined one, you would see what I mean.

After going through the service manual, the 3.5 hours my mechanic charged me seem pretty damn fair.

BTW, my mechanic told me that an aftermarket regulator would not work very well with the stock ecu as it would tend to run really rich off boost.

RX7 8U

iTrader: (1)

For about $150 from Mazdamotorsports you can get the fpr AND the fpd. Replace both while you're in there.....and might as well pull the injectors and get them cleaned by RC Engineering. ...and might as well do hose job...and ...and ...and........next thing you know your car is on jackstands for a month. I sure miss it. Last time I drove it gas was a buckfifty! This weekend on the road again!...I hope.

alwan16

replace the 8 injector o-rings while you are in there too if you are going to pull the fuel rails out. they are cheap compared to the fpr and fpd. just be careful taking out the injectors. i would recommend getting these from mazdatrix if you don't belong to mazdamotorsports.

maxcooper

The hose probably popped off -- get in there and check it out.

If you have two FPRs installed, the one that wants higher pressure will "win". If the hose fell off the stock one and you install another one, you will be rich under vacuum because the stock FPR will want full base pressure while the other FPR will want a lower pressure from the vacuum.

If you decide to remove the stock regulator and add an aftermarket regulator, you can set the base pressure to the same pressure as the stock one. It doesn't have to make your car run richer than it did with the stock regulator.

-Max

rynberg

Ok, thanks for the info Max. BTW, unless you are very modded and need the extra pressure, why would you upgrade the fuel regulator?

maxcooper

My car is very modded and I was running the stock regulator up until a week or two ago. I agree that you don't really need it unless you are doing something extreme with the car, or have other motivating factors (need a new regulator anyway and plan to mod the car a lot, for instance).

I upgraded to run a few more psi of fuel pressure like you suggest. I actually still have the stock FPR in there, but I plan to remove it soon. The aftermarket regulator is set higher, so it is controlling the pressure. I really haven't heard of too many failures of the stock regulator. Yours is the only first-hand account I have ever heard. Some people say that aftermarket regulators are more reliable, but the stock one seems pretty reliable to me. Even if the aftermarket regulator unit itself is more reliable, there are surely many more installation-related things that could go wrong, so it might be a wash overall or the stock unit as installed may actually be more reliable.

I also upgraded in hopes of avoiding a rich spot when my monster fuel pump goes to high speed. I don't think the stock regulator flows enough to dump all the extra fuel, and I was hoping the aftermarket regulator would be less of a bottleneck. I won't really know if that worked until I remove the stock regulator, though.

Aftermarket regulators are supposed to do a better job of keeping the pressure constant (with respect to the manifold pressure) when you stomp on the gas, but I probably won't be able to verify that one way or the other for sure. My unscientific impression is that my new regualtor does a better job (reacts faster), but the sensor is now much closer to the regulator and I might just be suffering from "my new part is awesome" perception delisions. If the regulator (stock or aftermarket) is slow to react, it could be dangerous for your engine, or just complicate tuning.

Lots of people install a regulator when they change the secondary rail or switch to SS braided lines. I stayed with 5/16 rubber lines for cost and convenience reasons, but the aftermarket regulator made it easier to mount my fuel pressure gauge sender in a good spot. I had it tee'd into the feed line before, and I think it read a few psi higher than the pressure really was in the rails.

Anyway, the stock regulator is fine for most cars and setups. There are a few operational-related reasons to upgrade, but it honestly isn't that clear to me that these reasons are valid. Running higher pressure is the one issue that is clearly a good reason to upgrade. The other ones may be fiction.

-Max

Domestic513

Ok anyone know of the easiest way to get to the FPR. I know where it is, I just don't feel like taking the whole top of the motor off to get it. Thought maybe going underneath might be alittle easier. Anyone?

Dougie_fresh_007

personally takin the manifold off doesnt take that long after u do it a couple times... but id go from teh top..... its sorta squeezed ni there so if u can get the lower manifold off it will be easier.... neone else have ideas? cause im jus guessin

rynberg

Max:

Thanks a lot for the great write-up (as usual, too bad your photography skills aren't as good ) and the good info. Yeah, my mechanic has been working on rx-7s a long time and this is the first one on an FD he's ever had to replace. Anyway, I feel comfortable with the fact that I replaced it with the stock part. I don't plan on ever going single (of course, things change...).

Domestic513:

The easiest and probably only way is to take off the upper intake manifold. I can't see how the hell you could do it from underneath at all, looking at where the FPR is and what's around it.