Return style fuel pressure regulator o-rings

nightbiker07

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Sep 20, 2020
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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

i'm familiar with penetration
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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.


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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nightbiker07

New Member
Sep 20, 2020
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Toledo
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.


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.


I don't have a caliper to measure these



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

nightbiker07

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Sep 20, 2020
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I ended up using one that was a little larger than the old one and it worked good.

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

Mustang Master
May 15, 2018
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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.
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.
 

nightbiker07

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Sep 20, 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.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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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.
 
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nightbiker07

New Member
Sep 20, 2020
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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!