All Big Six What recommended adjustable fuel pressure regulator?

Relates to all big sixes

Asa

2K+
VIP
I know that no one ever made one for the 300, I'm assuming that at least some of the SBF ones work? Anyone know which ones?
 

Bronctopia

Well-known member
I looked at this recently.

Aeromotive makes 2 Ford rail mount adjustable regulators, Sku 13102 and 13103. Neither are exact fits for our fuel rails, and would need some sort of clamp modification. I think I decided the 2 hole one would be slightly easier, before determining that a firewall mounted regulator would make more sense for me.
 

Bronctopia

Well-known member
Can't speak for the OP, but I had a run of OEM regulator failures over the last decade, and the 4.9L 58psi regulators are about double the price of the other 45 psi Ford regulators. I suspect they are mostly NOS, possibly with old rubber diaphragms that weren't engineered for gasohol.
In my case I am experimenting with larger injectors controlled by Microsquirt, and hopefully soon Speeduino. Larger injectors can have problems at low usage during idle if the required open interval is so short the physical pintle open and shut times eat most of the interval. Running a lower fuel rail PSI helps with this.
 

Bronctopia

Well-known member
Just realized I made the assumption that the OP wanted an adjustable EFI regulator. If he was needing it for carbureted application I assume anything that goes to a low enough psi range would work. Not being restricted to a proprietary fuel rail it would be just a matter of plumbing fittings.
 

Wesman07

Famous Member
Supporter 2020
Lol I made the assumption as well. He was asking about efi realated stuff recently.

The reason ford decided to raise the fuel pressure on these motors was vapor lock. Unless your running a cross flow head or a good fan to blow cool air down the intake manifold tunnel, your running a risk if operating in 90 plus temps.
 

Bronctopia

Well-known member
I believe in the last iteration of 4.9L EFI they reduced the fuel pressure?
I am not convinced EFI has the same vapor lock susceptibility that carbureted systems do. The majority of fuel in the rail returns to tank fairly quickly, to be replaced by fuel at tank temps. If the goal is to prevent or remove vaporized fuel, a higher fuel return flow at lower pressure would seem a better fix. Possibly with a longer prestart injector purge maybe keyed to intake air temp.
 

Bronctopia

Well-known member
Aeromotive 13102 is the 2 bolt mount.
13103 is the 3 bolt. Both are for the 5.0L.
Our 4.9L has a 3 bolt mount, but to a differently oriented triangle of bolts.

I think I measured that the 2 bolt would work with one bolt of our triangle, leaving the other to be fabbed by extending the mount plate to put a hole across the fuel rail toward the head. Then I came to my senses and decided an adjustable regulator should be mounted somewhere I could actually adjust it.
 

Wesman07

Famous Member
Supporter 2020
I have experienced it in crossing Kansas fully loaded in the summer.

The increased pressure does not remove boiled fuel faster. As you increase pressure the boiling point of a liquid also increases. This same principle is used with cooling systems as well.
 
Last edited:

sixtseventwo4d

Well-known member
Perhaps then some fuel rail alterations. Remove the regulator mounting style, weld on some AN style fittings and then you could have the remote regulator setup. Much like what you previously said. Pricey I'm sure for as little result for the application.
 

Bronctopia

Well-known member
Perhaps then some fuel rail alterations. Remove the regulator mounting style, weld on some AN style fittings and then you could have the remote regulator setup. Much like what you previously said. Pricey I'm sure for as little result for the application.

In my experience, the rubber diaphragms in the FPR are the failure point. Aeromotive offers these as a replaceable item. The OEM regulators have to be tossed. Last I purchased, the 4.9L higher pressure regulators were double the cost of the lower pressure V8 regulators. Since demand probably isn't higher than for the V8 regulators, I suspect the supply is tighter. When does supply go to zero?
Also, is anyone still even manufacturing these?
 

Wesman07

Famous Member
Supporter 2020
Wesman. Was your experience with vapor lock on attempting a hot restart?
It was actually on I70. It had to be over 100 degrees that day and the truck was really loaded. It was hot enough that we were putting ice on the dog. No, that is not a metaphor, we were literally buying ice at fuel stops for the dog. Flat black paint and no AC was not a good summer combo.

Anyway, the truck just felt like it was running out of gas. Lost enough power that it couldn’t move itself and idled very rough. After looking over 100 other possibilities the little light bulb flicked on in my head. I packed some ice around the injectors and tied the bag of ice around the fuel pump on the frame rail. That did the trick. Ice got us through Kansas.
 

Bronctopia

Well-known member
Thank you for the details.

Early 4.9L engines like mine had a blower system aimed at the injectors. Ford ditched this after a couple of years. They also ditched the frame mount fuel pump, and went with just in tank pump(s).

I suspect that for the very short OBD2 years, they may have run a lower rail pressure, at least in Vans, but haven't been able to verify this with a fuel gauge.
My suspicion is just based on Delphi part number changes, and listed PSI values in their application data.

I suspect the EFI vapor lock issue was mostly on the suction side of the rail mount fuel pump, but can't prove this without some expensive, uncomfortable, and possibly dangerous testing.
 

Bronctopia

Well-known member
I have a Siberian husky, so I fully believe and understand the ' iceing the dog ' part.
External iceing doesn't work so well with my model, due to excessive insulation.
Luckily, it does process ice by the oral route, tho prefers chips, or snowcone.
 

Bronctopia

Well-known member
Perhaps then some fuel rail alterations. Remove the regulator mounting style, weld on some AN style fittings and then you could have the remote regulator setup. Much like what you previously said. Pricey I'm sure for as little result for the application.
That was my first rail mod strategy. Gotser the TIG setup and experience with stainless, which I assumed this fuel rail was.
Till I put a magnet to it.
If it is Stainless, it is one of the strongly magnetic probably ferritic alloys.
I don't like the idea of guessing at filler rod with a fuel rail. Also, I found rust evidence inside of 2 fuel rails at the FPR mount plate. Even stainless will corrode in the right environment.
At this point I limited my adjustable FPR experiments to test stand only due to ghetto-fabbing the OEM garter spring to AN-hosebarb adaptor out of a junkyard plastic fuel return line.
Does anyone happen to know what alloy the 4.9L fuel rail was? At this point I'm looking at severe mission creep into Aluminum fuel rail fabbing territory.
 

Bronctopia

Well-known member
Curiosity is killing the cat. Is it a 2 or 3 screw regulator?
I found my etchings and sketchings when I looked into the Aeromotive Ford regulators. The fuel rail I measured had 35mm clearance between the central return port (smaller hole), and the edge of the supply rail tubing, which rises above the mounting plane.
Based solely on rescaling oblique website pics, I believe the non-flanged 3 bolt regulator has about 3 or 4 mm clearance.
It would, however, need 3 new screw mounts, one if which would be nestled between the supply port and supply rail.

If the 2 hole flange body of the 13102 could be re-clocked 90degrees, which looks like a possibility from photos, and the clearance to the supply rail fits or could be safely clearanced, then fabbing a mount for that seemed more reasonable.
It may even line up with the aft most screw hole on the existing FPR mount, or be close enough to add a stud. I thought nuts from above would be easier maintenance.
Once I found the OEM rail was magnetic, I put that project on hold, and wasn't willing to spend $180 just to take measurements for something I wasn't sure I could reliably weld.
 
Top