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johnsr11

No spark from plugs

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johnsr11

I have a workhorse gt 1848, I acquired this lawnmower and it had some problems. I have recently rewired it from a diagram for this model and replaced the magneto. There are 2 wires however coming off of the magneto that i do not know where they go. I believe it is for grounding purposes to kill the engine, if that is the case, do I hook the one wire to the magneto wire coming off of the key switch and then do I ground the other end of the wire? Also, there seems to be two wires coming from behind my flywheel, I believe these may be for the charging system. Does anyone know where I hook these up at so that the battery charges? My main concern is the fact that I am not getting any spark to my plugs! Any suggestions greatly appreciated. Thanks

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TT

Only one of the small wires from the magneto is needed. (cut the other one off at the white plug) It should connect to an insulated terminal on the engine shroud - where the "kill" wire from the ignition switch also attaches.

Did you "set" the air gap on the new magneto? (distance between magneto armature and flywheel - should be around .014", I believe)

Did you accidentally apply power to the kill wire?

One of the wires coming from the dual-circuit alternator under the flywheel is lighting power (should be black) and the other (should be red) charges the battery.

They should share a common (white) plug.

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johnsr11

Ok, thanks I will make sure to cut one of those off. Yes I set the gap for the magneto and I have not applied power to this magneto, I do not believe. The magnets are still working anyways, if that makes a difference. They try and attach to the flywheel when it gets close. I do not know if that would be useful information or not.

As far as for the alternator, Yes I see that one of the wires is black and one red, sharing the white connector. So the black one powers the lights, then that goes directly to my switch for my lights? As far as the red, that goes to the rectifier part of the key switch? I am referring back to the wiring diagram (manual) that you previously supplied me with.

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TT

The magnets are "permanent" and are attached to the flywheel.

Make sure the magneto is installed right side up too. (some have "CYL SIDE" cast into the coil and that must face the engine)

You are correct on the other two wires. :banghead:

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johnsr11

I flipped the magneto over and tried and still nothing. I may have possibly applied power to it and not realized it earlier this year when I was messing with it. Is there anyway that I can test the magneto to see whether it is bad or not? I appreciate all your help with everything TT!

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TT

Is there anyway that I can test the magneto to see whether it is bad or not?

To my knowledge - no.

But that just means I have never had the opportunity (or the need) to investigate the Magnetron style magneto.

I do know that the trigger on the newest version is sealed and would be completely ruined by attempting to open it up.

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johnsr11

Will the smallest and quickest jolt of energy ruin the magneto? I might have accidentally crossed a hot wire with the magneto wire earlier this summer, that is a very good possibility. I guess I will pick up a new magneto and try that, thanks for everything and I will let you know what I find out! Thanks again for all your help

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TT

Applying power to the "kill" wire will definitely burn out the trigger module. I don't know if it will harm the actual windings in the coil - but without a trigger, the coil is useless.

eBay item #330513383315 looks like a reasonable deal for a new mag. :banghead:

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johnsr11

I ordered the new magneto and installed it, made sure that no power was applied to the magneto and I still have no spark!! Any suggestions from there? I triple checked everything before I hooked it up, there has to be something else at play here. Could a bad switch allow it to turn over and still not allow spark to the plugs? I don't know, I am completely clueless. I was told something about if the key went bad on the flywheel that it wouldn't allow it to spark, but I can not get the flywheel nut off to check this. Any suggestions?!?!?

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WH nut

If its mag ignition you should be able to unplg the motor completely and jump the starter. All a mag ign needs is the motor to turn over to run. See if you hae spark. If you do, its something in the chassis wiring

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johnsr11

I unhooked everything from the switch except the battery and start. This was in assumption that the wire to the mag is just to kill it by grounding it, so that was disconnected for purposes of checking to see if there was spark or not. Then when I turn the key switch to start the lawn tractor the engine rolls over, and very well for that matter. However, I do not seem to get any spark from the magneto at all. I was holding the end that snaps onto the plug and felt nothing.

The magnet stills seems to be good on the flywheel, the mag will immediately stick to it when they are near each other. I am completely out of ideas, this is the 2nd magneto that I have put on this tractor trying to get her to fire again, I wouldn't think that there is much of anything else that would cause it not to have spark, it is an old and very simple design.

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WH nut

Discoonect the plug to the motor, take everything out of the equation. Use jumpers to spin the starter. If the plug is still connected and you have a wireing problem or switch you wont know until you know the ign. is good

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johnsr11

Sorry for the inconvenience, I had installed the magneto upside down. After looking at it and switching it around, I know have spark. This was my own fault, I just assumed that it went on the way I had it originally since the wires going to the plugs were coming out of the "top" of the magneto. Come to find out, that is not correct. Thank you so much for all your help everyone, I was ignorant while making these last few posts!

Thanks again

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WH nut

:banghead:

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TT

Make sure the magneto is installed right side up too. (some have "CYL SIDE" cast into the coil and that must face the engine)

Was the new coil marked? :ROTF:

Glad to hear it's firing. :banghead: :thumbs:

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johnsr11

Yes the coil was in fact marked, however, I had over looked that and installed it the first way that I threw it on. After 3 hours of wasted time messing with things I realized that I read on here before that they need to go a certain way. Then after tearing the coil back off and investigating, I realized that I had it on wrong. She works wonderfully now though!! I am gone for the weekend working at the moment however, but as soon as I get home Sunday I am going to finish working on her!

Thanks for the suggestion on the coil as well TT! That is the one that I ended up buying. Thanks again for everything guys

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