"Doug Vetter" wrote in message
My mechanic just replaced both main tank drains on our 172 after I
noticed the very same symptoms on one of the drains.

Lather, rinse, repeat a few more times to make sure
you remove any gunk that might be hanging out in the bottom of the tank.
When done, screw the new drain in, and safety wire accordingly.
Once we verified the gas in the basin was clean, we poured it into the tug.
Nothing wasted.
-Doug

Doug, you mention you drained the fuel several times to ensure you
"got the gunk out." I'm curious how your mechanic verified the fuel
was clean? Does one use a paper (coffee?) filter or some other
contraption to ensure the dark flecks & gunk don't get poured back in
the tank.

(Newbie owner and not a mechanic.)

Greg H.
Cols, OH
N4691X