Hello Fiero Guys and Gals,
Anyone have success adapting or building an adjustable fuel pressure regulator for the Allante 4.5 engine or the Cadillac 4.9 engine? I'm running out of ideas. Any suggestions or comments would be appreciated. Thanks!
Cheers,
John

It may be possible to cut the fuel pressure regulator from the fuel rail and weld/solder in a piece of fuel line. Then you can cap the return end and be able to locate an adjustable fuel pressure regulator with a T on the fuel line near the fuel filter. Just an idea but I believe it may work.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

The Northstar regulator is factory adjustable. IIRC, it fits the Allante and 4.9 (and most other GMs of the era...) fuel rails

quote Originally posted by Will: The Northstar regulator is factory adjustable. IIRC, it fits the Allante and 4.9 (and most other GMs of the era...) fuel rails

It would have to look like what is used on the 4.9L Cadillac engine;


I don't know of any direct fit adjustable regulator but maybe you can point the OP in the right direction.Looking on Rock Auto they don't seem to list a N* fuel pressure regulator anymore.

[This message has been edited by Dennis LaGrua (edited 01-09-2021).]

10+ years ago, guys were adapting the Aeromotive FPR for the Chevy LT-1 #13106.
https://aeromotiveinc.com/p...t/gm-lt-1-regulator/

quote Originally posted by fieroguru: 10+ years ago, guys were adapting the Aeromotive FPR for the Chevy LT-1 #13106. https://aeromotiveinc.com/p...t/gm-lt-1-regulator/

That regulator looks like it would be a direct fit on the 4.9L Cadillac rail but at $222 its a pretty expensive option.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Thanks guys! This may be a cheaper option?
John

https://www.ebay.com/itm/Ac...gulator/303769957044

quote Originally posted by Johns 4.9: Thanks guys! This may be a cheaper option? John https://www.ebay.com/itm/Ac...gulator/303769957044

Do it and let me know if it works so it saves me the trouble.

Quick look on RockAuto and all the regulators for the 1993 LT1 and 1995 4.9 are the same part number.

[This message has been edited by fieroguru (edited 01-10-2021).]

Is the Allante unit different than the PFI 4.9?

quote Originally posted by Will: Is the Allante unit different than the PFI 4.9?

Yes. ACDELCO 2173052

Unfortunately, that isn't the Allante regulator. Much different, not even close. Here is a pic of the Allante regulator.
Cheers

quote Originally posted by fieroguru: Yes. ACDELCO 2173052

That is the exact problem I had trying to source a regulator a while back. The pictured regulator is not what is on the Allante rail but all part numbers point like it is.

[This message has been edited by Spadesluck (edited 01-11-2021).]

This is what I am working on for the Allante adjustable regulator.
Cheers

This is what I have come up with for an adjustable fuel pressure regulator for the Allante 4.5 engine. I will test in the next couple of days.
Cheers

What do you have on the inlet? Compression fitting on the factory tubing? or Bundy adapter?

For the inlet, have you thought about making a fitting that would plug into the fuel rail, but then just have female 1/4" pipe threads? It could be turned in a single setup on a lathe, then oriented the direction the added fitting would need to go.