More details on your starting sequence please.
Do you normally use the glow plugs during your start sequence?
Does it always start easily if it has been running?
Does any smoke come out of the exhaust when it is cranking but won’t run? If so what color smoke is visible and how much is it? Same question when it is runnin.
If you have any suspicions about the cables please just replace them if they are not too expensive. You could also start with making all four ends of the cables are shiny bright and whatever they connect to is also clean and shiny. Or add a set of jumper cables from the battery cable clamps to the starter and ground to the frame. You would be surprised how many times that after a week or two of trying to find the problem the solution comes back with something like “cleaned all the cable ends” or “replaced cables “ and then the magic words “problem solved “.
Have you had the battery load tested yet?
What makes the starter start spinning again when it was not spinning properly before?
Please be a bit more specific about the words used, I understand that you have both a problem with the cranking (engine spins with starter) and also a problem with it not firing off and running if it does crank but have some confusion about when it does what since somtimes it “wouldn’t start”. I don’t know if it didn’t crank or didn’t run. I know that it is tedious but it does help us know that you mean. You can define your own words if you like other terms, just try to be consistent with the words used.
OK. I will be more clear. Since the tractor had been running and I just turned it off to fuel it up, I did not use glow plugs. Normally the first time I start the tractor it will crank and start right away.
The tractor normally starts right away whether its been running and warm or not.
No smoke comes out of the exhaust when it is cranking. Occasionally, if the tractor hasn't been run for a week or so, black smoke will come from the exhaust for a second after it starts. Never after it is already warm. No smoke comes from the exhaust when the tractor is running. Fuel filter was changed several months ago and was clean after the tractor cranked but did not start this last time. I replaced it with a new filter anyway. The air filter was cleaned several months ago also. I checked and it was OK.
I will check the cables to the starter today. I did connect an emergency power supply to the battery. The starter would spin the flywheel a little faster but still no start. I have not connected the emergency power supple directly to the starter nor jumper cables
The few times the starter would not spin, I would wait for a time and then try again. Eventually the starter would spin and the engine would start.
The battery was replaced 1 1/2 years ago so the battery should be OK. I put it on the charger last night and this morning it showed 13 volts.
The times I used the words"wouldn't start" refer to the starter spinning but the engine not starting. A few times when the starter would not spin, I tapped on the starter with a metal rod and turned the ignition and the starter would spin. That makes me think I have a starter problem or a cable problem.
The tractor is 11 years old with 900 hours on it. I have never had starter problems until just recently.
I appreciate your comments and desire to help. Thank you.