Thats impossible, the o-ring does nothing but seal the filtered fuel from the unfiltered fuel down inside the chamber, it does not keep the fuel from leaking out of the assembly, that takes place at the copper washer. The o-ring is way too far down in there to play any role in outside leaks. Fuel flows up through that hollow bolt and then out around under the bolt head/copper washer, then through that orifice to the IP.

I just tightened the heck out of it and now it seems to have stopped leaking. If it starts again I will get a new copper washer, and use that fairly tight, but with my orange sealant all around the bolt head too, that'll stop it.

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