As a general rule, a generator will have gas mixed in with the oil in the crankcase if there is a compromised float needle in the carburetor, or if there is a hole in the diaphragm of an external fuel pump.

To fix the carburetor issue, make sure that the float needle (which is often rubber-tipped) is not deformed, and if the float needle is metal-tipped, make sure the rubber seat is not deformed or split.

If they are, just swap out the part for a new one. If they both look fine, make sure the seat area is not covered in varnish from stale gas or any debris. You can use a Q-tip and carburetor cleaner for this.

If you have an external fuel pump, you will likely have to replace it. Take note of which hoses go where and hook up the new one accordingly. If you have an older external fuel pump, you may be able to take it apart and clean it and inspect for tears in the diaphragm. Newer ones are usually molded together and cannot be taken apart.

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