Sounds like the carb just needs to be cleaned. If it wasn't ran dry of fuel 3 years ago then more than likely the nozzle/jet is clogged. Years ago we could get away with letting a small engine sit with fuel quite sometime, but nowadays with the Ethanol laced fuels it will just gum up really bad if allowed to sit with fuel in the system. To avoid this problem in the future be sure and follow the owner manuals instructions on storing the mower and get you some fuel stabilizer to help reduce the bad effects of the ethanol. I tried to post a youtube link for cleaning a John Deere LT155 carb, but was not successful, I know it's not the same model, but the same principles apply. Just use the search function in Youtube and it should take you to it.

I'm not positive if this is the link that forum member rasims was referring to.

The video is a bit dark and could have been more precise in showing removing specific components but it will give you an idea. You may also want to look at the fuel pump mentioned in the video. There is also another thread you may want to take a look at:

http://forums2.gardenweb.com/discussions/1648151/problems-with-john-deere-l110

https://www.youtube.com/watch?v=cYU5UI4FfKk

Yes itzbinnice, that's the video, thanks! I'm new to this forum and thought I could just copy and paste, but I suppose I probably have to use the little Link symbol below.