john deere lawn mower

[lugnut610]

I have a john deere model L120 that runs ok but it surges bad when it is under a load, it did not idle like it should so I replaced the governor idle spring and now it idles ok but surges bad, can anyone tell me what my problem is

 

[ILENGINE]

Surging under load is normally means something goofy with the internal governor gear. Could also be caused by the two governor springs getting out of sync.

Does it surge without a load on the engine. Hold the throttle steady and see how it runs. If it runs poorly, then that usually means a dirty carb issue, or possible intake air leak. if runs steady then usually means mechanical governor problem.