Why the sponge in the gas tank?

It's a FILTER.

Probably the same reason they put them in race cars, some aircraft, etc. It acts like a baffle to the fuel does no slosh around and away from the pickup.

Why do you think it will decompose? It should not and I've seen them in good condition after years of use.

Those other guys are wrong , it's a contraceptive sponge . Can't have a bunch of little leaf-blowers around now can we ?

Terry:

Because it already has decomposed. Not sure if that is due to old age, ethanol in the gas, or gas stabilizer use in winter.

No, it's not a filter. It's apparantly there to prevent the vibration of the tool from causing the engine to draw air or fumes into the carburator instead of gasoline. I guess the sponge ensures that in a fuel tank that isn't full the gasoline doesn't slosh around in a vibrating engine fuel tank they way it would without that sponge.

'What is the purpose of the sponge in the gas tank'

replying to Steve Stone, Gary MCCONNELL wrote: What I can see is it keeps Air bubbles out but took mine out and have had no problems

replying to Ed Pawlowski, Gary MCCONNELL wrote: It does decompose I just took one out of a engine gas take from a go cart and it was decompose