Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I see no one has replied, do you still need help? If you work the throttle at the carburetor manually, will speed increase? Not just throttle cable problem? Have you checked the butterfly in the carburetor to see if it is moving? If all that checks out, remove the float bowl on the carburetor ad see if the float and needle valve are free and filling the float bowl with fuel.
OK, take a look at the link above.