Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Is throttle cable moving at lower control? Are springs on place?
Is the cable slipping under the clamp?
Is the carburetor loose on the cylinder head, may a bolt fell out!
If not, have you drained the carburetor and checked for water?
See if the throttle valve is loose on the shaft!
Remove the solenoid in the carburetor, it may be sticking, and it will let you clean the float bowl.
Does the engine have the pulse fuel pump? Is it working?
no, that is anti-backfire solenoid, it plugs the main jet. Fuel pump would have three lines, between tank and carb.