I am looking to install an adjustable fpr on my B16a. I will be adding the Walbro 255 fuel pump since I will be running a 75hp wetshot, and don’t want to risk the chance of going lean. The adjustable fpr is to lower the fuel pressure back down since the walbro will increase the pressure. My car is a 91 model, and I swapped in the B16a, obviously. The thing that gets me is that AEM shows that the 90-93 integra rs, ls, gs, g-sr fpr part number is different from the 94 delsol b16. Therefore I have reason to believe that the fuel rail is different between the b16 and the other bseries motors, or at least the obd0 fuel rail is different from obd1/2 rails.
Simply put, I don’t know which fpr to get. I am not fixated on AEM as if I have to have it. I am open to any brand that has given great results. I have searched this forum, but I haven’t seen anything that will directly tell me what I need to know.
I went with the b&m. It works on pretty much all fuel injected hondas. It uses your stock FPR… you use a dremel or hacksaw to cut off part of it, and bolt the b&m parts to it. Sounds janky, I know, but it’s a really great design, doesn’t leak, and does what it’s supposed to do, for about the cheapest price you can find. It’s been a while since I’ve done it, but the directions were pretty clear, IIRC.
I have done much research and have found that the B&M fpr can only raise the stock fuel pressure. It cannot lower it as I would need it to since I am going with the Walbro 255 pump.
Oh, I see… well, if you want to keep stock fuel pressure, then you just keep your stock FPR. The pump might push more, but as the name suggests, the “Fuel Pressure Regulator” is what determines the fuel pressure in the system.
In my case (I went with a 55 shot) I wanted to increase the pressure, because I was worried about a pressure drop when the nitrous fired. I then used my VAFC (and later BRE) to re-tune everything for the higher pressure.
I see what you’re saying, but if I keep my stock fpr the fuel pressure would be way too high after I install the Walbro 255 pump. I have always been under the assumption that it’s best to have a bigger pump, but regulate it down so that fuel supply will always be constant and won’t ever lean out. What i’m assuming here would be the same as what’s done with having bigger injectors and then slowing down the duty cycle to accept the larger injectors. I may be thinking about this wrong, but my thinking is that if the ecu doesn’t like the nitrous/fuel jetting that I use, and it happens to need more fuel, it has the potential to correct it by adding more fuel just as a dry nitrous system does. It’s just a little insurance I guess.
Are you trying to say that the factory fpr is self-adjusting? I would think that it’s pressure settings are static. The way I see it, if you install a higher flow pump, then the fuel pressure and flow would be to high, and then you would need to regulate it down.
A FPR is a little diaphragm that maintains a constant pressure. It doesn’t matter how much the pump is pushing, the FPR will always ensure that the pressure remains within the desired range (depending on vacuum). If you put a 255lph pump in, that alone won’t change your fuel pressure.
I don’t think the factory regulator self-adjusts. I can tell you one thing, if you were to go from a Holley black series fuel pump to a Barry Grant 400 series pump without touching the regulator, you’d probably blow the needle and seats out of the carburetor.
What I would like to know is which adjustable fpr’s part# (such as one from AEM) fit’s the first gen B16a fuel rail?
The B&M FPR can lower your puel pressure. To almost 30 psi.
As for the stock FPR, If you change the pump the stock regulator will work fine. Its made to regulate at that certain psi. Think of it like this, an aftermarket FPR can raise the presure by opening itself further, but wait… the pump psi was already threre! Your stock pump is pushing more than your regulator is set at, hense why they use them. You will not harm the stock FPR at all.
While it looks like blakkvtec agrees with me that if a FPR is doing its job properly, it shouldn’t care what the fuel pump is pushing, I think I’m gonna have to eat my words on this one. Found this article:
Looks like with the 255lph pump and a b&m regulator, the outlet hole in the stock FPR just isn’t large enough to cope. The article is about a workaround, but I will agree that it’s a decent amount of effort just to save $50. I didn’t have that issue since I went with the 190lph pump… with that and the B&M FPR, I had no problem setting the fuel pressure to stock specs for the couple weeks I ran it that way. I never tried it without the B&M add-on, but I don’t think I would have had problems then either. But according to H-T, lots of people have had problems getting the fuel pressure below 40psi with the stock FPR and the 255lph pump.
So in any case, AEM part number 25-303 looks to be the right one… that’s the one they list for 2g integras and 4g civics.
[QUOTE=steronz;1806143]While it looks like blakkvtec agrees with me that if a FPR is doing its job properly, it shouldn’t care what the fuel pump is pushing, I think I’m gonna have to eat my words on this one. Found this article:
Looks like with the 255lph pump and a b&m regulator, the outlet hole in the stock FPR just isn’t large enough to cope. The article is about a workaround, but I will agree that it’s a decent amount of effort just to save $50. I didn’t have that issue since I went with the 190lph pump… with that and the B&M FPR, I had no problem setting the fuel pressure to stock specs for the couple weeks I ran it that way. I never tried it without the B&M add-on, but I don’t think I would have had problems then either. But according to H-T, lots of people have had problems getting the fuel pressure below 40psi with the stock FPR and the 255lph pump.
So in any case, AEM part number 25-303 looks to be the right one… that’s the one they list for 2g integras and 4g civics.[/QUOTE]
I like your honesty and really appreciate your help. So it looks like the b16a fuel rail is same as the b18a and b18c as far as fuel regulator compatibility is concerned. I would have guessed that the b16a required a special fpr. This thread has helped me very much.