Weak battery maybe
Try putting a battery charger on the battery for several hours, then try to fire it again.

I have an angry one that sometimes requires me to hit the battery charger on boost to get it to turn over

Sometimes the brake/clutch is not fully depressed, and sometimes I have to wiggle the deck engagement handle a few time

Those micro switches sometimes act up

But if it is 3 yrs old, check the battery first, put a charger on it, then test it to see if it is holding

you can get a new one at Walmart for 20 bucks or so

" Is it possible adding too much fuel or other problems? "

Not adding too much fuel, apparently other problem(s). I would remove the spark plug and see if it turns over. Be ware that gas MIGHT squirt out the spark plug hole if the engine is hydro locked caused by leaking carb float needle.

Posting the make and model number of the engine might help get info.

Walt Conner

Many causes to your dilema. Battery voltage too low, compression realease out of adjustment or a failed starter relay/motor. If you remove the spark plugs, and the motor spins, electrically, battery and/or CPS are suspect. If you hear the click when the starter is engaged, but motor doesn't spin you can eliminate safety switches. The clicking is the starter solenoid exciting which it will not do if a safety circuit has activated. A test light will confirm it's operation. The side from the battery is powered at all times. The side to the starter only lights when the key is turned to starter position. Probe the starter side, set the brake, and activate starter normally. If the test light lights, starter or CRS or battery are suspect. Remove spark plugs. If still will not spin, starter bad. If light fails when in start position, starter relay(solenoid) has failed(most common). Hope this helps, Dale Koven

Thanks for all your replies. My JD tractor model is 125. It has been for 39 months. I have just got a charger and will test the battery first. I have three questions about charging the battery.

1) Can I set the charge rate to 4A or 6A for fast charging or I have to set it to 2A, charging for small batteries?
2) Can I start the engine while charging the battery or I must disconnect the charger before start the tractor?
3) If charging cannot be completed, does it mean the battery is completely dead and the new battery is needed?

You need just a bit of clarification on using that charger.
If all you have for setting options (amp ratings) is 2, 4, & 6 AMP, you SHOULD NOT engage the starter while the charger is connected to the battery! Small chargers like this don't always have good "overcurrent" protection (internal circuit breaker) and the load of the starter being applied to the charger could be the death of the charger. UNLESS a charger features a selection for "Boost Start" or something like that, never engage the starter without disconnecting the charger first.
If the battery is very much discharged (weak) you will need to leave the charger connected for around 24 hours at 6 amp before the battery will gain enough capacity to function in cranking duties. (amount of charge in battery determines the exact amount of time at a specific amp rate to reach full charge). Having the battery tested by a competent shop could reveal whether the battery is shot or not.
Another issue to cover in "no start" situations is whether corrosion has developed in the large cable circuits that serve the starter system. Both battery post connections, both large posts on the starter solenoid, the starter cable on the starter case, as well as the frame/engine connection fastener for the battery ground cable, MUST ALL BE TIGHT & CLEAN. You can't always determine if those connections are clean & tight just by looking at them! You have to take them loose, inspect the cable end and the place it connects to, to eliminate corrosion as a problem. Always disconnect the battery negative cable before setting out to loosen/clean/tighten any connections of any of the big cables.

Does anyone have experience in trouble shooting it?

If it me I would get pass the battery first by taking it out and taking it to an auto parts store and having it load tested. 3 years is about all you get out of cheap batteries. Now that you know you have a known good battery your troubleshooting can begain IMO, If it don't start of course. If i was a gambler I would lay 10 to 1 on it will. I also think even if you get it to charge enough to start the LT will will probably go dead again due to one or more cells dieing IMO.

I would also recommend some general reading on how things work on my LT cause the older it gets the more problems you are going to have and three things will happen. you will get another LT Tractor? Or you will pay for the repairs? Or your general knowledge will enable you identify and repair minor problems. I say minor cause you are probably not going to overhaul the engine or transmission? anything else would be minor IMO.

This reads pretty "good".
***"Posting the make and model number of the engine might help get info."*** (quote, Walt Conner)
***" My JD tractor model is 125. It has been for 39 months."*** (quote, coody)
Is something missing from the second sentence above?

Got it. ItÂs battery problem. I have it tested. I was told "extremely low" Buy a new one at $23 from a Wal-Mar. Then the JD 125 starts. The JD is very smart. They code the JD battery warranty B, 36 months. I got the tractor for 39 months. So I have no chance to claim the warranty. In addition, the charging light changed to green. I thought the battery had been fully charged. But I still could not start the engine. I do not know why the charger can display "green" light while the battery is still not good? I learned if the click sound can be heard but the engine cannot be started, the battery should be tested first instead of jump start or charge.

I have a D125 John Deere lawn mower. When I tried to start for the first time this year the battery was dead, so I put it on a charger. After it was all charged up, I tried to start again and all I get is a clicking sound. Not just one click but a continuos click click clicking noise. The starter does not engage. Any suggestions?

It sounds as if the battery is toast. SO if the connections are clean and secure, have the battery load tested at an auto parts store.

Make sure the charge is working properly. I put my battery on the charge over night. I put the battery back in the charge and it was still so low it would not turn over the tractor. I pushed the tractor up to the drive, and started by jumping it with the car. I have driven the tractor several times in the last week and it started every time.

SO instead of buying a new battery, I will buy a new battery charger next fall.

I replaced the spark plugs, air filter, fuel filter and battery. It turns over but doesn’t start.

what can the issue be?

If it‘a bad gas how do I drain the old gas?

I have a John Deer 125 automatic, new battery, jump to starter, it turns over, jump it to solenoid, it turns Iverson turn the key to start, nothing happens. No click, no nothing.