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Discussion Starter · #1 ·
New guy here. I have a JD 317 garden tractor that I have been battling for weeks. I parked it last fall and it ran fine. This spring, it's a no go. I have
no spark from the points or plugs. I have replaced the points, condenser, plugs and coil. I have also checked all the wiring and haven't seen any fraying or damaged wires. It cranks over strong. I've cleaned the neutral switch and pto switch and they all seem fine too. What in god's name am I missing?

Thank you!
 

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Welcome to MTF twistedwhitty! Lots of info here and great members to help and share with, enjoy the site! Here is some site navigation assistance in case you need it:

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If the engine is cranking then it isn't likely safety switches. What engine is in it?
 

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Twisted, Here's the wiring for a 317:
2509107

Check that pto switch is "Off" and that you have 12 volts to coil with key "On". If no 12 volts, probably bad pto switch...VERY common issue! Bob
 

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Perhaps the kill wire to the coils is being grounded somewhere?
 

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On a simple coil/points system like this, my first check is to see if there is power to the + terminal of the coil when the key switch is in the run position. A 12 volt test light works well for this. A multitester should work as well. Then check if it is still there when cranking. Now check the - terminal of the coil while cranking. The test light should flash on and off as the points open and close.
 

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Discussion Starter · #9 ·
On a simple coil/points system like this, my first check is to see if there is power to the + terminal of the coil when the key switch is in the run position. A 12 volt test light works well for this. A multitester should work as well. Then check if it is still there when cranking. Now check the - terminal of the coil while cranking. The test light should flash on and off as the points open and close.
I'll try that tonight, I appreciate your comment!! Thank you!
 

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On a simple coil/points system like this, my first check is to see if there is power to the + terminal of the coil when the key switch is in the run position. A 12 volt test light works well for this. A multitester should work as well. Then check if it is still there when cranking. Now check the - terminal of the coil while cranking. The test light should flash on and off as the points open and close.
I agree with this. If this test shows negative you can run a fused jumper wire from the battery to the 12v+ terminal on the coil and see if it starts. If it does you know the problem lies in the wire feeding the coil, or the key switch.
 

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Years ago my 317 kicked my butt for a few days - would crank healthy but never start. I replaced points and condenser - came close to replacing the expensive coil. It turned out to be a grounding issue. Off the negative batterry terminal is a thick cable (I think it lands on the engine) and a thinner wire that attaches to the body. The thinner wire was not well connected. I wouldn't think that would affect the points since they are on the engine - but that was my issue.
 

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Discussion Starter · #13 ·
Years ago my 317 kicked my butt for a few days - would crank healthy but never start. I replaced points and condenser - came close to replacing the expensive coil. It turned out to be a grounding issue. Off the negative batterry terminal is a thick cable (I think it lands on the engine) and a thinner wire that attaches to the body. The thinner wire was not well connected. I wouldn't think that would affect the points since they are on the engine - but that was my issue.
The thin wire on my tractor was really dirty but sadly that wasn't the issue. I'm starting to think my PTO is the problem.
 

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Discussion Starter · #14 ·
I agree with this. If this test shows negative you can run a fused jumper wire from the battery to the 12v+ terminal on the coil and see if it starts. If it does you know the problem lies in the wire feeding the coil, or the key switch.
Thanks for this! I will try this weekend. I have been wondering if my PTO is the problem as well. We shall see. Electrical gremlins are a pain.
 

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Twisted, To check pto: Disconnect wire to pto. Set meter to "Ohms" and attach one meter lead to connector going to pto and second meter to case of pto where it attaches to block. If 3-4ohms, pto is good. If 2.5 or less, pto is bad. Bob
 

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I think if the condenser if shorted to ground (bad condenser) it would not let the points break the fire to the coil and then there could not be any fire out the coil. IMHO :)
 

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sparklie, Correct. When points open, magnetic field generated by primary windings collapse causing a HUGE discharge... like 25-40 thousand volts!.. from secondary windings to spark plug. If condenser is shorted, it's like the points are never opening and mag. field never collapses.

A quick check is to simply disconnect the condenser from the coil - terminal. NOT good to run like this for hours though as it will burn the points. Bob
 

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sparklie, Correct. When points open, magnetic field generated by primary windings collapse causing a HUGE discharge... like 25-40 thousand volts!.. from secondary windings to spark plug. If condenser is shorted, it's like the points are never opening and mag. field never collapses.

A quick check is to simply disconnect the condenser from the coil - terminal. NOT good to run like this for hours though as it will burn the points. Bob
That is good to know Bob,-- for a quick check of the condenser. I like to learn. tk u very much. sparklie__________________
 

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Thanks for this! I will try this weekend. I have been wondering if my PTO is the problem as well. We shall see. Electrical gremlins are a pain.
You're welcome! I'm not sure on the 317, but on my 110/112 SF the pto switch prevents the starter from even turning as it cuts power to the ignition switch. Just a thought. I'm sure some other 317 owners can prove me right or wrong.
Be sure to let us know how you make out.
 
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