Onan spark plug

It's a 13/16ths, a true spark plug socket has a rubber insert in them, make sure you are pushing it on all the way, they can be a little tight when not used a lot. I just changed mine in a 3600lp Microquiet. I am having starting problems also, only starts after a lot of cranking.

It's an Onan microquiet 4000. 5/8" is too small, 11/16" is too small, 3/4" is too small, 13/16" is too big ... Could it be metric? Perhaps I can get the heat shield off so I can see the whole plug. Access is a little awkward. This all stems from failure to start. It would start and run a few seconds, now it doesn't even try. It is getting a good spark from the wire terminal. The genset has only about 125 hours. Meanwhile, I'll check gas line. Thanks for your suggestions.

If you have a Microquiet 4000, I believe the spark plug it uses is the Champion RN14YC (similar to the Onan plug). Tighten it to 13 ft-lbs. Gap is 0.025. This plug has a 13/16" hex drive.

If you have a different generator, then the information above is useless to you!

Most spark plug sockets are one of two sizes: 5/8 inches and 13/16 inches.

What are the Model Number and Spec Code of your GenSet?