Previos talk about residue from ethanol in fuel

[SailingLoto]

This isn't off a sailboat, but a pwc. Water/fuel/ethanol result in this white slime/corrosion quite often.

It seems to vary slightly year to year. It's been green, yellow, brown. I assume due to the fuel additives.

This one doesn't have the grains you see in outboards. That comes from the fuel line liner.

 

[thinwater]

Aluminum, corrosion, resulting from moisture absorption in ethanol fuel. It does not have to be enough to settle out, only enough to allow ions to move more freely.

The cure is dry fuel and a good anti-corrosion additive.

• For dry fuel, with an installed tank, the best bet is a silica gell vent filter. Try H2OUT.
• For an additive, Stabil 360 Marine (not the red stuff) and Biobor EB have done very well in independent testing. Many are snake oil, or at least are not formulated for saltwater (which is very different from lawn mowers).

If you are getting grains from the fuel hose, the hose is decades out of date and desperately needs replaced with ethanol compatible hose. I would not blame that on the fuel!