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Return style fuel pressure regulator o-rings

  • Thread starter Thread starter nightbiker07
  • Start date Start date Sep 20, 2020
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nightbiker07

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As the title states, I am searching for the o-rings for the return style fuel pressure regulator. See pictures.

Autozone and the like don't have anything specific, and the generic kits don't have anything close to the correct sizes.

Only way at this point I can see getting new ones is to buy a new fuel pressure regulator.

Problem is, I bought a new Aeromotive adjustable regulator last spring. Didn't come with o rings. So, I re used the ones on the old regulator. They leak like crazy.
Due to other things, I sidelined the project for a year.

Coming back to it, I can't find anything.
Lots of talk about others having leaks due to re using old o rings. But all threads are 10 years old, and not one mentions what to buy or where to buy it.


It's a 1998 explorer engine in a 2002 Ranger. But, the return style fuel rails are the same as the explorers, as are the regulators. I am here because I figure way more people have been into upgrading their mustangs than people on explorer forums.
 

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Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
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Massachusetts
Sep 21, 2020
#2
  • Sep 21, 2020
  • #2
O rings are standard sizes. If you have a set of calipers, you can measure and compare and come up with the correct size -dash number.

AS568 O-Ring Size Chart | Marco Sealing Solutions

Interactive standard o-ring size chart to find Parker and AS568 o-ring size dimensions. Order Online millions of o-ring sizes are in-stock
www.allorings.com

From there, you might be able to find a small pack on Amazon, or if not you can order from Mcmaster-carr.

as for material, Viton is widely used in automotive fuel seals.
 
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96pushrod

I think they're a little easier to get off
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#3
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I was able to use some from a harbor freight viton oring kit.
 
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nightbiker07

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Mustang5L5 said:
O rings are standard sizes. If you have a set of calipers, you can measure and compare and come up with the correct size -dash number.

AS568 O-Ring Size Chart | Marco Sealing Solutions

Interactive standard o-ring size chart to find Parker and AS568 o-ring size dimensions. Order Online millions of o-ring sizes are in-stock
www.allorings.com

From there, you might be able to find a small pack on Amazon, or if not you can order from Mcmaster-carr.

as for material, Viton is widely used in automotive fuel seals.
Click to expand...


I don't have a caliper to measure these



96pushrod said:
I was able to use some from a harbor freight viton oring kit.
Click to expand...
I have their 180 pc viton kit. Nothing is close enough in size that it would work.
 

96pushrod

I think they're a little easier to get off
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Sep 21, 2020
#5
  • Sep 21, 2020
  • #5
nightbiker07 said:
I don't have a caliper to measure these




I have their 180 pc viton kit. Nothing is close enough in size that it would work.
Click to expand...
I ended up using one that was a little larger than the old one and it worked good.
 
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nightbiker07

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96pushrod said:
I ended up using one that was a little larger than the old one and it worked good.
Click to expand...

The kit I have goes from way too small to literally dropping over the nipple on the pressure side.
All these o-rings are considerably thinner than the OEM, and my leak is coming from the return side. The thickness of the o-ring is what seals that side, not the inner and outer diameter.
 

96pushrod

I think they're a little easier to get off
5 Year Member
May 15, 2018
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Sep 21, 2020
#7
  • Sep 21, 2020
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nightbiker07 said:
The kit I have goes from way too small to literally dropping over the nipple on the pressure side.
All these o-rings are considerably thinner than the OEM, and my leak is coming from the return side. The thickness of the o-ring is what seals that side, not the inner and outer diameter.
Click to expand...
Might have been an oring out of their nitrile kit. I just stuck a slightly fatter oring than the factory one and it sealed fine.
 
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nightbiker07

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#8
  • Sep 23, 2020
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I found the Ford part numbers.
N807543s is the part number for the two larger o-rings.
N811064S is the part number for the smaller single o-ring

Problem is they want six bucks each for the larger that you need two of, and 18 bucks for the smaller o-ring.

For that kind of money a Delphi fuel press regular can be had that has the o-rings on it.

This has to be one of the most absurd things I've ever had to track down.
 
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nightbiker07

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And none of the listings I can find for the OEM parts offer dimensions of the o-rings
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Sep 23, 2020
#10
  • Sep 23, 2020
  • #10
I literally had one of these regulators in my hand a couple weeks ago and then sold it (and the rail) on ebay.

Can you post up a pic of the O-rings on a tape measure so I can get a reference? I have bags and bags of O-rings, but need a size range. Some are Buna, and some Viton. I can send you some if we can figure it out. (and then post the info for future reference)

EDIT: Ok, I just looked through my selection of O-rings and do not have a large amount of smaller sizes, and most are not Viton, so I may not have the right O-rings to give you. Still, it would be helpful to post some pics of them laying on a tape measure to try and figure out the size.

Looking at the pics, they are either the 0.070" or the 0.103" thick O-rings. You would just need then either an OD or an ID and can usually figure out the correct -dash number easily.
 
Last edited: Sep 23, 2020
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nightbiker07

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Sep 24, 2020
#11
  • Sep 24, 2020
  • #11
I will buy a cheap caliper from harbor freight and measure these things to get exact dimensions. It would probably be a good tool to have laying around anyway.

I'll get them measured in post my findings here. Thank you!
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Sep 24, 2020
#12
  • Sep 24, 2020
  • #12
Throw an @Mustang5L5 in your post so I am sure to see it. SOmetimes replies don't pop up in my alerts and I can miss a post
 
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DOHCtor

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May 23, 2004
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Aug 28, 2021
#13
  • Aug 28, 2021
  • #13
Old thread I know, but for anyone needing this in the future

Ford #87006-S96 - o-ring seal, two required. Brown.
Measured dimensions - .073" thick x .290" ID x .425" OD


Ford #N807244S - one required. Brown. Similar to o-ring, but flat.
Measured dimensions - .065" thick x .278" ID x .435" OD

Regulator inlet tube / groove .310" OD
Regulator outlet tube .235" OD
 
Reactions: j753303 and Mustang5L5

Cartel

Member
Aug 24, 2009
22
2
13
May 9, 2026
#14
  • May 9, 2026
  • #14
hello its the future calling...
the new regulator from ford comes with no square oring and has a "gasket" is this good enough?







This is what its supposed to be...looks like ford is cheaping out. that gasket is causing the regulator to not sit flush is my guess.
This is the 3rd part I bought from ford that sucks.

I just took the "new" regulator off and already the cheap black oring is cracked. I put the 30 year old one back on, the orings are still holding.
what a nightmare

 
Last edited: May 9, 2026
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