FPR & Motor Swap issue
 

I'm installing the fuel rail on my new BP4W with factory intake manifold. The problem I'm having is the fuel pressure regulator doesn't fit with the intake manifold and the fitting

https://www.miataturbo.net/attachmen...ine=1344217887

I'm thinking since the FPR is off a 90-93 car, which may be the problem.

The part # on my fuel rail is b61p-13-280. I haven't run into any detail that the fpr from a 1.6 won't work but the 94-97 fpr is definitely configured different. Is it that much shorter that it will fit without issue? if so, I guess I'll be posting in the WTB section soon.

-Greer

The NB have two types of fuel rail. You need the one that has the port for the FPR in the front part of the rail. Then you can just mount the FPR. I can take a picture of mine tomorrow if you don't get what I'm saying.

I saw this in the FS section. What you need is the first rail https://www.miataturbo.net/miata-par...jectors-67621/ (no affiliation)

lol what? what you need is a 94+ fpr and turn it upside down or you need to cut your 1.6 fpr.


http://users.telenet.be/miata/englis..._head_swap.htm

There is at least one additional type of NB fuel rail, the JDM/EU one for 98-00, which is a return type and have a 60psi FPR.
E.g. (197) 1998 Mazda MX5 Mk2 Fuel Injectors & Rail | eBay

or
MAZDA MX-5 MK2 98-05 1.8 FUEL RAIL | eBay
+
MAZDA MX-5 MK2 98-05 1.8 FUEL PRESSURE VALVE / REGULATOR BP5B 795300-3730 | eBay

But that might just be the same NB rail with a FPR+return instead of a damper (I don't have a US rail to compare to).

Twibs, thanks for the help. From your photo it appears the fpr fits the front of the engine, which is probably my other problem. When I installed, I presumed the FPR fitting went to the back of the engine like my 90-93 motor did. I will reverse and try again tonight. However, i'm using an Mtuned rail and I'm not sure it can be reversed as it appears the 99+ are done. Maybe I'm wrong, will experiment tonight.

Better Photo:
https://www.miataturbo.net/attachmen...ine=1344255750

One more question. From the link you provided was a section:
"You will need to reuse the solenoid for the fpr of course. On the M1 intake it's mounted on top on the manifold. The M2 intake has not enough room to install it there. Instead I moved it to the side of the intake, a bit under the vics actuator, next to the throttle body."

Is there another "solenoid" that I'm missing. I don't remember one in the fuel path. I thought the path was fuel hard line, fuel rail, fpr fitting, return.

Thanks,
Greer

I believe the solenoid is the where the vacuum hose exiting the FPR goes to. Is a little rectangular box (I think...) that sits on top of the intake manifold. Be careful to set this hoses in the right order on you could have your hoses bursting a la kool-aid man, ask me how I know...

I've been trying to figure out what exactly that solenoid did. It looks like all it could do is prevent the fpr from seeing manifold pressure if the ecu wanted to.

So I got a 94-97 FPR in, and the stupid thing still doesn't fit. It smacks head long into the EGR valve or the side of the intake manifold. While I won't be using EGR anyways, if unscrew the top half of the valve, the FPR will fit.

To be clear:
91 Miata
BP4W engine
MTuned fuel rail
using FPR port on the top side of the fuel rail.
FPR won't fit.

Is there something I'm missing? (besides the Mtuned instructions). Do I need to drill the FPR port on the bottom out and use it for this config? I can't be the first person to run this config, so obviously I'm missing something.

-Greer

I just removed the stock fpr from the equation on my m-tuned install. I just used a 1/4 npt to -6an adapter and rand straight from the fpr port to the inlet on my AEM fpr.

I had the same problem and went for a dual feed rail as well. I picked up an $18 eBay adjustable FPR and it has served me well for 6 years. One of the cheap things that actually pay off.

Well I'm building a custom IM anyways pretty soon, so the fit shouldn't be an issue once I get that, but down the road the adjustable FPR and better injectors are on the list.

Was hoping that I was just missing something obvious, turns out to be a design issue?

-Greer

Yeah with a stock rail it would fit but it looks like it doesnt work with the m-tuned.