There is an o-ring between the AFM and the FD but it's purpose is to seal for vacuum. The fuel leak will come from the plunger seal in the center of the bottom of the FD. This is a tricky seal to change because you have to measure the static height of the plunger before removal so that you can put it back where it came from. I'd mke sure that the leak is coming from there before I changed it. I changed mine and it didn't help. See if this helps.My LAST ovp/eha question, I promise!!!!