Is there an o-ring required on the hard line to and from the fuel filter? Took the fuel lines off at the filter to replace it and no o-ring was present. The hard-line looks like it requires an O-ring. If it does require an O-ring what size?

Size not sure.

You cannot use normal black ring... will seal but won't last.

OE is orange made of different "rubber." (Viton)
example: http://www.dormanproducts.com/p-30428-800-013.aspx
get at most parts stores.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

You can get the "o" rings at NAPA or O'reilly. There is two different sizes the fuel line takes They come in a box of two each. Dorman and BWD makes them

O Reilly's has them. 2-5/16 and 2- 3/8 inch . Expensive for 4 o rings. Here's the link.
http://www.oreillyauto.com/...3463&keyword=800-013

Ummm... wait... what?

I've done several fuel filters on my Fiero(s) and I've never seen o'rings on either side of the fuel filter. It's always been a threaded nut into the filter itself like the brake system hard lines at the fluted ends. I imagine you could Teflon tape the threads if you wanted.

I've seen newer cars with fuel filter o'rings for the quick connect type fittings but not older GM cars like ours.

Am I missing something?

Just some useless information,

Viton o-rings can come in different colors as well, for example:

white: http://www.mcmaster.com/#o-rings/=13606cw
black: http://www.mcmaster.com/#o-rings/=13606m7

quote Originally posted by KMFDMFAN: Ummm... wait... what? I've done several fuel filters on my Fiero(s) and I've never seen o'rings on either side of the fuel filter. It's always been a threaded nut into the filter itself like the brake system hard lines at the fluted ends. I imagine you could Teflon tape the threads if you wanted. I've seen newer cars with fuel filter o'rings for the quick connect type fittings but not older GM cars like ours. Am I missing something?

yes and you're wrong...

When used, O-ring is on the hard lines.

Fiero has them on main Fuel Filter, TBI units, and other joints/parts.

My 87 duke, their on line ends for Fuel Filter, 700 TBI, and 2 Fuel Line joints below the battery. That's just the places I've seen.

[This message has been edited by theogre (edited 07-06-2016).]

Man I haven't been paying close enough attention...

Could these o'rings be bad and allow air to enter the fuel system but not have fuel leaking out?

I'm trying to trace a noticeable fuel pressure loss.

[This message has been edited by KMFDMFAN (edited 07-06-2016).]

The Lines are "Pressurized" so fuel Can leak out, But because tit's under pressure, air can't leak IN

No leaking outside then injector(s), regulator, and/or fuel pump have problems.
Possible line inside the tank is bad but most times you can't start the engine for low pressure.

quote Originally posted by Lou6t4gto: The Lines are "Pressurized" so fuel Can leak out, But because tit's under pressure, air can't leak IN

Plus "Air" is likely boiled fuel.
Many systems will have some to a lot of fumes when you open Pressure Test port on the fuel rail. Very normal but many still can't understand.

1. Gasoline can Boil as low as 100°F w/o Pressurization.
2. Opening test port w/ engine warm to hot in same issue as opening hot coolant system by simply removing the Radiator cap... Hot fuel/coolant will instantly boil and flash you w/ fumes/steam.

Even Duke w/ test adapter could see same depending just where the adapter is used. Example: Old Dukes, fuel filter/adapter is on top of the engine bay and area can get warm/hot or just close enough to other hot parts.

quote Originally posted by Mickey_Moose: Viton o-rings can come in different colors as well, for example: white: http://www.mcmaster.com/#o-rings/=13606cw black: http://www.mcmaster.com/#o-rings/=13606m7

True but unless you know for sure is Viton or some other brand to resist hot fuel... Don't use black o-rings.

Black o-ring lives matter.
But seriously, teflon tape melts away with fuel contact. At least in my experience. Wouldn't bother trying it.