Pretty much finished up with tank inspection.
Decided to replace fitting on top of tank with a brass one,went to three different places, and,
while at the third place discovered a ball bearing within the fitting (hadn't noticed that before).
So, it is a check valve coming out of the tank = keeps tank from siphoning out if damage happens to hose down the way etc, etc ......
Got it back on and re-installed tank and sewed her up ....
Put Speck Detector's portable tank in and ran engine awhile = all good.
You can see where red washer is in the water/fuel separator (on bottom), if it gets water in it the red washer floats on water
but not in gas .........
Next good weather day will take her out for a fishin/runnin trip and see if any water winds up in the fuel/water separator etc, etc .....