I easily started up my John Deere 990 tractor and drove across a field. I killed the engine as I worked to place a chain around a fallen tree. Then when I got back onto the tractor it would not start. After towing it back to the barn I visually checked the different safety switches for foreign objects. The seat switch sometimes falls out of position but it was ok. I purchased a new battery with the same specs, 840 CCA, 1010 CA. I cleaned the cables and the opposite end of the ground wire to the frame. When I try to start I hear the fuel pump and solenoid but the engine barely moves at all, maybe one cylinder at a time. So I purchased a new starter, no difference. I have tried jump starting from the battery directly to the starter. I have tried with the solenoid wires to the tractor connected and not connected using a jumper wire from the solenoid to the starter (still worried about safety switches). Someone asked me to check the actual voltage readings...with the brand new battery installed in the tractor it is 12.6 and drops to 4.3 when starting, indicating a bad cable. But when I disconnect the new battery and try jump starting from my truck to the starter the battery is 14.3 and drops to 10.0 which should be more than enough. Truck amps are the same as the tractor. Soooo, now I am wondering if it is an electrical problem at all and out of ideas. The engine does turn a bit on each attempt and not seized up. What do I check next? We have made so many attempts...could the cylinders be locked with fuel? Even though the amps are good it seems like there isnt enough power to turn it over. I have looked at lots of other threads but nothing takes me to the next step. Thank you for any ideas!!!!
John Deere 990 wont start
- Thread starter Tim00
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LouNY
Super Star Member
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- 11,933
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- Greenwich, NY
- Tractor
- Branson 8050, IH 574, Oliver 1550 Diesel Utility (traded in on Branson) NH 8160. Kioti CK2620SECH
Place one lead of your meter on the positive terminal of your battery, the other lead on the large stud of the starter solenoid to the starter motor.
Check the voltage while someone tries to start it. If you have more then a couple of volts you have a bad cable or solenoid.
You can repeat this to check the solenoid,keeping one lead on the positive battery post and the other lead to the solenoid that the battery connects to you should be at "0" volts when you have some one try to start it you should only show a volt or so, the less on both tests the better.
Check the voltage while someone tries to start it. If you have more then a couple of volts you have a bad cable or solenoid.
You can repeat this to check the solenoid,keeping one lead on the positive battery post and the other lead to the solenoid that the battery connects to you should be at "0" volts when you have some one try to start it you should only show a volt or so, the less on both tests the better.
Thanks! I did this and it dropped from 12.6 to 4.3 so I agree there is an issue but visually the wire looks good. So next I disconnected the suspect positive lead at the starter and connected a jumper cable to my truck. The voltage dropped from 14.3 to 10.0. My understanding is anything above 8.0 is good. And the jumper cables were brand new out of the box because my old cables clamps were useless. I can check the solenoid on Monday but Im not sure what to do with that info?
jaxs
Elite Member
Have you tried pull starting it? If you don't know how or never pull started before,ask for experienced help. Preferably both people have experience pull starting so I'm uneasy trying to tell you how. That would establish if something is binding up to stop engine from freely turning.
LouNY
Super Star Member
- Joined
- Jul 4, 2015
- Messages
- 11,933
- Location
- Greenwich, NY
- Tractor
- Branson 8050, IH 574, Oliver 1550 Diesel Utility (traded in on Branson) NH 8160. Kioti CK2620SECH
If your meter is from the positive post of your battery to the starter stud, you should have full battery voltage till you try and crank, at that point the closer to "0" volts the better.
When checking from the positive post of the battery to the hot or battery connection of the solenoid you should have "0" volts till trying to start the voltage that shows when trying to start is how much you are losing the more the worse your connections or cable is.
Most jumper cable made today are almost worthless, lousy clamps and #10 wire. The connections are poor and the wire to small.
