I have a 6 year old Briggs 17.5 hp lawnmower engine #31C7070154E1 with Nikki vert shaft carb. Had mowed 15+ minutes with no problem when it just stopped. Now will start and run 2-3 minutes when cold & momentarially afterwards, Replaced plug & fuel filter and notice filter seems to have a very low level of fuel showing after a minute or two. Will run regardless as long as I inject carb cleaner. Same problem with ground disconnected. Breather hole in fuel tank cap is clear.

Sounds like a carb problem. Do I need to rebuild it or is there a possibility of something else?

Thank you for any help you can provide.

Allen S