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XLR99

6512.5 Briggs Twin no spark while cranking

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XLR99

Hi all, I apologize for asking for tech help on my first post, been lurking for awhile. My google-fu must be weak, so I'm looking to see if anyone has heard of this situation before.

I have a 6512.5 tractor, which has worked flawlessly for the last 12 years. Last week my son was mowing and the tractor died and would not restart. I discovered that mice had moved into the engine shrouds. Cleaned out the disgusting nests from above the cylinders, and replaced the coil because the critters had chewed off the insulation from the wires.

I discovered that the effing mice had chewed the wiring harness under the steering wheel, so I spliced in new wiring as needed. I was assuming that there was a short somewhere. Put everything together and still no go.

At this point, the issue is that I have no spark while cranking, however, when I stop cranking and the key goes to 'run', there IS spark for the couple of revs while the engine spins down.

Any ideas? I've confirmed I have the switch wired correctly. Just found a shop manual with wiring diagrams, so I'm starting to look at that for ideas as well.

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OkieGT

I posted here yesterday that my simplicity 7016 was having the same kind of spark issue and is doing the same thing, I get spark when I stop cranking and the engines spins down. I thought it was that I had installed the wrong coil. I haven't had any definitive answers yet, I'll be watching this post.

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powerking_one

This engine should have a Magnetron dual plug wire configuration. As a basic troubleshooting step, remove the ground/kill wire from the coil DIRECTLY and re-test for spark. If it runs, then you will need to back-track the wiring of the primary terminal of the coil to see what is shorted. If with the primary dis-connected and there is no spark, then the coil is most probably failed/defective.

Tom (PK)

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XLR99

Interestingly, if I pull the ground wire from the coil, the engine will not crank. Seems like there's another short in there somewhere.

I'm leaning toward something with all of the safety interlocks. The PO had all of these disabled before I bought it, and they're all jumpered under the seat to lock them out. Need to start digging in that direction I guess.

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XLR99

Thanks TLH, that's what I was thinking. However, to make it even more exciting, the module is no longer there. I did a bit more digging, and rather than a module, the plug is jumpered. The red wire coming from the M terminal on the switch is jumpered to a yellow wire that goes to the solenoid.

I'm starting to think about pulling out the entire thing and wiring it up from scratch.

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OkieGT
quote:Originally posted by XLR99

Thanks TLH, that's what I was thinking. However, to make it even more exciting, the module is no longer there. I did a bit more digging, and rather than a module, the plug is jumpered. The red wire coming from the M terminal on the switch is jumpered to a yellow wire that goes to the solenoid. I'm starting to think about pulling out the entire thing and wiring it up from scratch.


id="quote">
id="quote">You might want to troubleshoot the the problem, then rewire it

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XLR99

Just realized I forgot to come back and update.

Okie you're right - I was just getting aggravated with it at the time!

The issue turned out to be a chewed up ground wire that's part of bypassing the interlock module.

Quick fix, but it points out how it can add to the challenge of troubleshooting if things are modified.

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