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Discussion Starter #1 (Edited)
Hi all, new to JD tractors and, well, tractors in general. A couple of weeks ago, I plowed my driveway with my JD, which is marked as a model 67, although, from research, it would appear to be a 750. Got about 1/2 way done then had to leave for a few hours.

When I came back, the tractor would not start. The starter motor does not seem to engage at all. In addition, when I inspected the motor, I found a loose wire (has black sheathing but the color of the inner wire is white with what looks like a pink stripe but could be red), which could be the culprit. I will attach a photo of it (sorry, the forum turned the photos upside down) and where I think that it might go, although I do not recognize, nor have I been able to find any sort of identifier as to what it is. It looks like a glow plug to me, but I honestly haven't worked on a non-marine diesel engine that was designed or built after 1980. If it is a glow plug, that's not the issue as I use a block heater.

There is only a clicking sound when I turn the key to the start position. It seems to be coming from the gas tank, so I'm guessing that it is a fuel pump, although my hearing sucks, at best.

Following are the solutions that I have tried:

I have tried jumping it with both a dedicated booster and with my jeep, but it does not seem to improve the situation.

I have tried shorting the starter to get it to turn and it does not.

I have looked at about 50 different wiring diagrams that say that they're for this model, but none of them seem to have a wire that matches the loose one.

Any help that you fine people could give would be much appreciated!
 

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I’d say you have some dirty or worn brushes in start motor.


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I’d say you have some dirty or worn brushes in start motor.


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Agree, is there some sort of solenoid to engage the starter? That would also be an easy fix. Is that where you by passed the circuit? The brushes replacement and solenoid replacement is covered in many you tubes. With a volt ohm meter you should be able to ring out the problem.
 

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I’d say you have some dirty or worn brushes in start motor.


Sent from my iPhone


Agree, is there some sort of solenoid to engage the starter? That would also be an easy fix. Is that where you by passed the circuit? The brushes replacement and solenoid replacement is covered in many you tubes. With a volt ohm meter you should be able to ring out the problem.
Agree, sounds like a starter problem.
 

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Discussion Starter #5
Agree, is there some sort of solenoid to engage the starter? That would also be an easy fix. Is that where you by passed the circuit? The brushes replacement and solenoid replacement is covered in many you tubes. With a volt ohm meter you should be able to ring out the problem.
I was thinking it was likely a starter problem, but the loose wire in the picture is what threw me for a bit of a loop, wasn't sure if that had anything to do with it. In that same picture is the starter motor with, what I'm pretty sure is, the solenoid attached to the bottom (it is the bolt with the cover slightly pulled back and the 2-3 wires in it). I jumped that across to the ground and just sparked, didn't engage the starter at all.

I do have a multimeter. That pole read 12.8v the other day. What additional steps should I use to try to diagnose where the problem lies?

Thank you all for your help so far!
 

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My dad recently had to service the starter on his 750, but I think it was just the starter drive that he needed to replace.

Sounds like the fork that attaches to the solenoid and engages the starter drive might be broke on yours, I’d start by replacing the starter.
 

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Discussion Starter #8
Thank you all for your replies. We finally figured it out and it seems to be either a bad spring or a bad switch on the rear differential lock.

It sounds silly but I guess that if the diff is locked, the starter is disabled. What is happening is that the lever for the lock (as of its worsening today) needs to be pulled all the way to the top whereas before, if it were simply disengaged, the starter would be enabled.

I'll be trying to figure out which it is, but, since I really did not have much experience with the tractor running correctly (I think that it ran correctly for me about 4 times), I don't so much know how it is supposed to look.
 
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