Just throwing this in for info, as I just found out about it a couple of weeks ago. Had a customers 9.5 Ev in as it would not stay running. Did my usual look over, and found an old single ine fuel connector o ring, motor side. He had the old dreaded grey Sierra hose. A nice member and friend sent me a few OMC "O" rings, but were too big, mighta been Sierra, dunno, but he got them from an OMC dealer. Out of desperation I tried a McMaster Carr double line o ring and it worked perfectly. Installed easily, sealed on the motor and off the motor (no leaks), tried the hose on and off several times and he reports success.
Dunno if these type of double line o rings will work with an OMC single line connector, but sure did with the Sierra type. You might try one if you have one.
If you need a few, let me know, we'll set ya up.
outboardrepair1 @ gmail .com