I have a john deere sabre 16 hp ridin mower. It has been sitting 4 3 years. It cranked right up after a spark plug and a cleaning of the jets in the carb. but there is still a problem with my ignition.When I turn the key It clicks the float on the bottom of the carb the electric part of it but the starter will not respond not a lick. I crank it by jumping the starter with my truck. If any has a clue what could be wrong I would appreciate a little advice. Im thinking cyllinoid but I'm relly not sure. Thank u.

Solonoid..

Test it and jump it with a screw driver.
Ignition "key" switch could have a problem

To check the solenoid, remove the wire from spade terminal. With a screw driver, touch the spade terminal and the hot side of the solenoid. If the starter turns, the starter solenoid is good and there is a problem in the safety switches. The solenoid is usually located on the back side of the accessories panel, in the engine compartment, on Riders and Tractors. On Rear Engine Riders, the solenoid is located under the seat or in a seprate compartment. Follow the Positive (Red) battery cable to find the solenoid.

Also check your grounds. By sitting around for so many years corrosion will in fact be there providing an insulation keeping a good ground. By jumping your JD with a much larger battery which has more amps that will produce more heat through the ground and positive ends creating this mower to start. Less Amps mean less heat through the cables which stops at any corroded connection.. Also I am sure the fuses in this are push in type fuses if any. I had owned a JD 16HP rider years ago and never had a problem with it. They made many model each year and were made for several years too. If you do have a glass fuse which I doubt, moister inside the fuse will prevent continuity passing through a wet fuse. A much high amp battery may pass through your fuse also. Check both ideas also with all other answers provided. Engineering is one on a drawing that suppose to work when made. Breakdowns amount to numerous senereos I afiad toi say