fuel reg O ring

[Chas54]

Ive lost my fuel reg 'o' ring and having measured the hole and the pipe , I thought the ID was 8mm & the OD was 12mm.
I have just received some 2mm section 'O' rings but they definitely feel wrong. I am certain the one i've lost was a thicker cross section , a bit like the injector O rings. But they are not the same size as the regs.
I know the reg outlet pipework does feel a bit flexible on the correct O ring seal, but this 2mm ring just feel a bit to loose.

Ken S has a thread suggesting 13mm but mine definitely wasn't so i'm a bit stuck .

any suggestions welcomed

[Chas54]

On second thoughts, Ken S was likely to be right . My outside diameter I measured as the 12mm boring in the reg valve and 13mm may be the outside diameter of an O ring with ID 8mm and 2.5mm cross section.
Anyway, that's what i've ordered now.

[KenS]

Hi, just to clarify, the 13mm ID x 2.5mm section O ring is for the regulator fit into the fuel rail, the O ring that you need for the fuel feed pipe is smaller diameter. The regulator bore is about 11.8mm, so a 12mm OD O ring sounds correct, but I don't have a measure for the o ring section. I have not replaced that O ring, but I do know that the connection is well known to be surprisingly flexible! When you confirm a good size it would be useful to post the info for future reference - good luck. (KenS)

[Chas54]

Thanks Ken, that's cleared it up .
Ive ordered two sets Viton o rings , 2.5mm section 8mm ID and 2.5mm section 7mm ID. I think its probably the 7mm ID item as the old one I had never tended to slip off the pipe stub whereas the 8mm ID 2mm section ring does slip off.

I will of course announce any success I have, although seeing your comment about the reg valves commonly being a bit loose, may mean I could have got away with the 2mm section. the seal is actually the pipework flange about 10mm back from the pipe end and the inner step inside the reg valve.



Regards
Charlie

[chris]

The pipe is dia 7.8mm and the aperture dia 11.6 so if you use a 2mm section oring you run the risk of a fuel leak as you won’t have enough compression on the oring ! I’ve chosen to go with a BS109 oring in viton 90; it’s a slightly harder material and solves the fuel regulator exit pipe wobble.