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Discussion Starter #1 (Edited)
My car is a 1991 Daytona CS, stock T1 fuel rail.

I'm looking to replace my stock fuel pressure regulator with a FMU. To do that, I'd like to find an adapter that would bolt in place of the stock FPR and allow a pipe thread to adapt to AN6. I see the FPR is common to other cars such as the Buick Grand National. I can't find an aftermarket adapter. I drew one up on e-machine shop (see attached picture), but making just 1 is $140 (3D printing is not an option). Seeing as how there would not be any interest in making and selling extras, I was wondering if anyone ever made one of these. I see a lot of them for imports on ebay, but there is no way to tell if they would fit.
 

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Discussion Starter #2 (Edited)
I hacked up my stock FPR (cut it on the fitting side of the seam) and think I may have a solution.

The inlet part is where the difficulty arises in making a replacement. The outlet part consists of a 14mmx1.5 Saginaw o-ring fitting, which can be easily adapted to AN6 male. I elected to drill it out to 37/64 and tap it for 3/8 pipe to open up more choices.

The outlet side has a tube that can be cut away with a Dremel. The 37/64 drill took it out in my case. I used a rotary stone to clean up the inside.

The body of the unit is about 1.5" diameter and has to be capped. I found a freeze plug that I think can be welded into place. The 1.375 (3/8)" ones are too small. A 1.4375 (7/16)" would be a good fit, but they are not sold as a "cup" style, only the thinner "concave" style. Dorman sells a 36.5mm plug as part #555-103 and they are usually carried at local auto parts stores. According to my micrometer and Dorman specs, they are about .018" larger in diameter than my opening. I'm thinking I can notch the lip of the cup to clear the inlet pipe, press it into place, and then have it welded.

I'm taking some pics and will update here after it is completed.

EDIT
First batch of pics added.

Edit 2
The 3/8 NPT fitting interfered with the injector. If an AN adapter such as the 14x1.5 to AN6 part were used, this would likely clear.
 

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Just for discussion, have you considered using a log fuel rail??

Advantages are they flow more fuel and don't have a regulator mount as the regulator is remotely mounted.

The disadvantage is the mounting tabs need to be remade.

I've personally never converted a log rail but Russ Jerome has posted his success using a log rail years ago.

Also, there are some past posts on TD about welding/soldering fuel rails if you need any in put in this regard.

Curious on your reasons for using a FMU ??

Thanks
Randy
 

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Discussion Starter #4
Just for discussion, have you considered using a log fuel rail??

Advantages are they flow more fuel and don't have a regulator mount as the regulator is remotely mounted.

The disadvantage is the mounting tabs need to be remade.

I've personally never converted a log rail but Russ Jerome has posted his success using a log rail years ago.

Also, there are some past posts on TD about welding/soldering fuel rails if you need any in put in this regard.

Curious on your reasons for using a FMU ??

Thanks
Randy
I'm trying to get this car going again in as little time with as little money as possible. I'm trying to avoid removing and replacing parts like the intake. If I can make OEM parts work, so much the better.

I have a neighbor that runs a small welding/machine shop, so if the freeze plug idea is feasible he will be able to tell me. If not, I'm out under $1 and I have some other options. I've used him to weld a fuel rail for a motorcycle project and he does good work at a really decent price.

As for the FMU, it has a reworked ECU that didn't do what it needed to do- the car ran incredibly poorly- like 10-15 MPH. The programmer has not responded to my follow up inquiries, so I need to work around the ECU. Upon doing some reading, I found a FMU can adjust flow to my 53 PPH injectors and allow the car to return decent economy. The FMU I plan on using covers both regular pressure (allowing it to be set down to 25 PSI) and greater than 1:1 pressure under boost. My plan at this point is to reinstall a stock programmed ECU and try the FMU.
 

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I haven't been following your journey but it sounds complicated.

FWIW, I was referring to the OEM 1984-1987 T-I log Engine fuel rail.

Best of luck.

Thanks
Randy
 

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Glhs60 was referring to utilizing the TI log rail with your current intake. As I understand, the log rail can be found easily and cheaply.
This option would provide a clean install and reduce the risk of leakage, or worse, fire!
 

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Discussion Starter #7
Glhs60 was referring to utilizing the TI log rail with your current intake. As I understand, the log rail can be found easily and cheaply.
This option would provide a clean install and reduce the risk of leakage, or worse, fire!
Thanks. I forgot to add my car has a two-piece intake manifold if that would make a difference, I added that when I relocated the turbo. The rail that is there now looks kind of like a log, it has two mounting brackets with two bolts each, with a round compensator on the driver side. I don't know enough about these rails to ID what I have, it's been almost 6 years since I was working on this project.

I found a pic on this site that looks like what I have. The seller listed it as a TII rail:
 

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Glhs60 was referring to utilizing the TI log rail with your current intake. As I understand, the log rail can be found easily and cheaply.
This option would provide a clean install and reduce the risk of leakage, or worse, fire!
You hit the nail on the head!!

Thanks
Randy
 

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Discussion Starter #10
The stock 2 piece fuel rail is filmy.

I bought myself this so I don't have to deal with it.

Aluminum Fuel Rails
Thank you, that looks like a good alternative. I've already converted my inlet line to AN6, and bought an adapter to convert the return line to AN6 as well. I'm presuming it inlets on one side and returns on the other?

You hit the nail on the head!!

Thanks
Randy
I appreciate the clarification as well, the nomenclature TI, TII etc. is somewhat confusing as Dodge calls my 1991 2.5L engine a TI but apparently there was an earlier version with the same identifier. I'm used to Chevy motors and codes such as LT1, LS1, L33, etc. They have done the same thing over a greater span of years (e.g. 60's vs 90's LT1).

I'm going to check with the shop today and see what they say about brazing the OEM part. If it can be done, I'll give it a pressure test to check for leaks. If not, then I'll look at the TU rail linked above.
 

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Discussion Starter #11
I have another question re the aftermarket rails. I see FWD makes one for an aftermarket regulator as does TU. Both are within a few $ of each other. The posts I'm finding on this site are all pretty old. Is there any advantage to one over the other? It looks like the TU rail may use AN fittings as-is, while the FWD one may be 1/4 NPT.
 

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The original 1984-1987 T-I had the log intake and fuel rail with draw through turbo.

1988 and newer T-I were blow through with rail mounted regulator and more restrictive internally.

Two piece intakes used a unique rail that seems to be the most flimsy of them all.

There are some prior posts on welding/soldering rails here.

Advantage of the log rail is it cheap, flows better, built for remote regulator, and no welding required.

Mounting tabs are different but easy to work with.

Thanks
Randy
 

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Discussion Starter #14
I got the brazed part back today and with the 3/8 NPT fitting in place it interferes with the fuel injector, and then a second interference was the return line fitting out of the FMU. Would likely have cleared the injector if I had used the 14mm x 1.5 to AN6 adapter. After reading the posts here, I'm going to invest in an aftermarket fuel rail. I found the original one from my engine (1991 T1), so the one I'm using was from another engine.

I measured the old rail for spacing and bolt patterns and drew one up using e-machine shop (pic attached). $210 to make one, but if 10 were made the cost would be < $50.
 

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Discussion Starter #15
As an update, I ended up making two adapters for the OEM fuel rail using a couple of steel 90 degree 1/4 pipe to AN and o-ring fittings. These are available at Discount Hydraulic Hose. I had a Dorman 800-151 5/16 steel fuel repair line brazed in so I could use an o-ring where it goes into the rail. You can flatten the tip of it so it retains the o-ring. I then cut a 1/8 angle iron to the dimensions of the OEM regulator mount and had it welded to the fitting. It bolts in place just as the OEM regulator did and allows an AN6 outlet.

I'm using one fitting on a fuel injector flow tester I built (this one is a pipe to -10 o-ring due to the pressure regulator inlet) and the other on my car, which is the AN6 male. Both have been tested to over 60 PSI with no leaks.

I have attached pics of the adapter and the front and rear of the injector tester.
 

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