The current filter and lines inside the cowling are 5/16. As you
mention, that's what I was wondering - is 5/16 stock? Apparently yes.
Thanks for the info. HH

wrote:
For what its worth, my large 80's V6 johnson has the larger line
running to the engine (I'll assume its 3/8 without looking at it -
definitely larger than the fuel lines at the fuel pump, etc. inside
the cowling) and inside it's 5/8. The little fuel filter inside the
cowling is definitely 5/8 (just replaced it). I'm not sure if you're
asking just so you'd know which to buy (in which case, you could just
remove the old one and look at it), or if you're wondering if 5/8 is
stock and/or the proper diameter. I do believe it is the
original/proper diameter for those lines.