Orange/yellow gunk from generator cap?

[wardster]

I recently ran my generator for 2 days, pretty much non stop. When I was closing up to head home I noticed that there was a bit of 'gunk', 'sludge' that appeared to be coming from the air vent hole in the fuel cap for the generator. Has anyone experience this? Fuel was not old. Cheap maybe, but wasn't sitting around in the garage for weeks....

[Household6]

Well, since vented gas caps are one way, I don't think it's something pushed through the cap from the tank. Gas caps shouldn't leak stuff to the outside, unless the check valve mechanism is busted.

The first thing I wondered (because of the color) is if the vacuum is pulling in pollen from the air and it's collecting on the vent..

But I wonder if the cap is just bad and the adhesives inside are starting to fail... I'd just put a new gas cap on my shopping list..

It's running just fine though? Not dying randomly or anything?

[wardster]

I wasn't even thinking of the fact the one way vent sucked in vs. releasing pressure out. That makes much more sense. It is running fine, no issues at all.... so far. I'll be back there this weekend and will take a closer look as I noticed it while I was leaving. I was just unsure if this was something common since my lifetime usage of a generator is extremely limited.

Thanks for providing your thoughts!

[TitanMike]

When moisture and petroleum products are mixed vigorously (the vibration from the engine) you can get a yellowish colored "sludge" about the consistency of warm margarine/butter. It usually appears on the inside of Oil Filler caps but under the right circumstances you could see it at the vent of a gas fill cap.

Next time you need to fill the tank on the generator remove any screen that might be in the fill hole and shine a light into the bottom of the tank. Move the generator back and forth to see if there is any water starting to accumulate in the bottom.