Calmdown

Sometimes when your a newb with parts from 3 different variants of 1.8 motors laying around you... You go with what fits. Then you forget about it, because it did fit.

That was my thinking over a year ago, when I mated a 2001/mk2.5 fuel rail to a bp4w head. All the lines were in the right place... I didn't have to use a hammer.

I'd forgotten about that until I started chasing down a terrible idle. Then I read up on the swap again, and popped the hood to verify. Sure enough, front mounted fpr, return fuel lines... Part number on the fpr shows its for a mk 2.5...

I've got a 99 returnless coming in, what do I need to do to make it fit? Can I use anything from the mk2.5 rail? Or am I going to have to get something from a breaker?

psyber_0ptix

iTrader: (4)

Ok....just to be clear...

What year miata are you running this motor in?

If you get a BP4W fuel rail, you just need to attach a 94-97 FPR upside down on the front (which sounds like what you've already done) and run the return line. For the feed, you can get a Dorman 800-092 fuel line adapter fitting converting it from quick connect to barb.

Reverant

iTrader: (10)

He has a 94-95.

So you were probably getting "all of it" fuel pressure? That could explain the bad idle.

psyber_0ptix

iTrader: (4)

So he kept the pulsation damper on the front and no fuel pressure regulator? I'm contotally fused.

Reverant

iTrader: (10)

Probably so.

krissetsfire

iTrader: (1)

You need it to be a return system. Return-less would indicate your fpr does not have a return side. On the 99 it has a Damper in the fpr location. You can use the 99-00 rail I think as I did but just put an fpr on from 90-97. Assuming your car is an N/A of some sort.

Edit: for accuracy.

Dunning Kruger Affect

You need a 90-93 FPR because the 94-97 FPR won't fit on the 2001-2005 motor.

So to recap, in order to get a VVT motor working in an NA:
90-93 FPR
99-00 Fuel Rail
In a 1990-1997 car
With a 2001-2005 motor.

Calmdown

Apparently there is/May be a variant fuel rail for the 99-01? The fpr on the front has a part number of BP5B 795300-3730. It has a return line and a feed line parked up front near the throttle body. There's a few threads on here about it, but nothing definitive.

Under a Mazda parts search, it shows the 2001-2002 moats with a 13290c pulse damper in the front. Shows the same for all of them.

Now I'm really confused. Are mk2/2.5 fuel rails the same?

I've got a 99 coming in anyway, so does it need to be a mk1 1.8 fpr, or can I use a 1.6 as well?

Just asking because I'll be calling junkyards to see what they have .

Dunning Kruger Affect

It needs to be a 1.6L one because the 1.8L NA one doesn't fit.

krissetsfire

iTrader: (1)

Okok yes thanks dunning. Confirming what he's said. You need a 90-97 fpr and a 99-00 fuel rail. Confirmed as that's what I've done to my bp4w in my 90. You'll have to tweak the neck of the fpr though with a pipe or something. The 94-97 fpr will not fit on the 99-00 fuel rail which is why you chose the option of 01+ your current fpr i'm guessing. I mis-spoke according to some documentation i had saying 99-00 but they switched to vvt in 01 as mentioned which is why this cleared up for me. When they switched to vvt they changed the intake manifold .... anyway yeah thanks dunning!

psyber_0ptix

iTrader: (4)

That's weird. I'm using a 94-97 fpr on a 99-00 rail and it works fine. (upside down)

The 90-93 fpr would interfere with the intake manifold


the return barb sticks upward near the TPS

krissetsfire

iTrader: (1)

Maybe the 94-97 works? I had a 1.6 so I was just reusing the parts and everything I read said to re-use it.

With the 90-93 fpr you have to flip it upside down and then tweak the barb so it has less of an angle. Mine ended up as shown. As far as i know the only real difference between the 2 fpr's is the sweep in the 90-93 and then the vacuum line orientation. The vacuum nipple is more likely to bump into the IM but If psyber says his works then it may.



One on left is 94-97 right is 90-93

Edit: grammar/typo fix

Dunning Kruger Affect

IDK, I just re-read the OP and it's coming off as a fever dream where he doesn't explicitly mention what the chassis is and keeps on including 2001 with the NB1s.

As far as I'm concerned, he might have the ultra rare 1998 Miata.

Leafy

iTrader: (1)

I dont think that would work with an 01+ head and it might not work with any manifold that isnt a flattop.

Dunning Kruger Affect

Why is your hardline to the PCV pointed towards the front of the engine? What the hell is going on here? Who are you people?

krissetsfire

iTrader: (1)

lol i think you're not seeing that right. The fuel line dips out before the pcv. That is a fuel line. I'm not sure what route I took there as it was on the stand there. I probably had it tucked under a runner so it wouldn't be hanging out floppin around.

If you're not referring to my picture then I don't know what you're seeing that i'm not. I don't really see any hard lines anywhere in any of these pictures.

psyber_0ptix

iTrader: (4)

I thought he was using BP4W head?



I just followed:
http://blog.choppedoctopus.com/2012/...94-engine.html


The barb was reoriented because I'll be using that as a vacuum source for other things. PCV will be running to a catch can

Dunning Kruger Affect

I was talking about the other guy's, the red valve cover.

I have the return line from the FPR on my VVT swap going up and over the PCV IIRC. Aka: your setup.

Savington

iTrader: (31)

94-97 FPR aims the atmospheric reference directly at the intake manifold so you can't get a vacuum line on it (or if you do, it rubs on stuff). 1.6 FPR with the outlet slightly straightened clears everything.

Calmdown

Did some more digging, apparently the EUDM market MK2's had return lines?

MAZDA MX5 EUNOS (MK2 1998 - 2005) 1.8 - FUEL INJECTOR RAIL | eBay (Item just shown for reference! Don't shoot me!)

Mk2 1.8L - Std Fuel Rail Pressure - Forced Induction & N/A Power Mods - MX5Nutz Forum

If so, I just blew 50 quid :(