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Fairbanks Morse FMX4B44A

nrp3

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Working my way through a customers Kohler 7.5R62. We got as far as there appears to be no spark. This is a bit different than what I'm used to for generators, but an interesting challenge nonetheless. Did some looking and similar rebuilt ones appear to be available, but not sure if this exact one is available. Would save me from trying to rebuild it myself, or knowing yet whether it's capable of being rebuilt. It turns over, there is gas pressure (propane), spark doesn't appear on the tester, simple clip on clear plastic Kohler provided spark tester. It does make the clacking sound I've read about.
 
The "clacking" sound is the impulse coupling that spins the magneto when cranking speeds are slow...perfectly normal. It quickly flips the mag over to obtain spark for starting, then disengages when the engine starts.

Look for a service manual or bulletin on the internet. I've found many free for the downloading.

As to no spark, it could be a number of things. It could be as simple as the "P lead" being grounded. This is the connection on the outside that grounds the primary winding to stop the spark and hence, stop the engine. If there's a wire connected to it, remove the wire and try to start. If it starts you know that wire (or button, or relay) is grounded somewhere. Simply touch the wire to the connection to stop the engine and then begin looking.

Assuming it's built like other mags, I'd pull the cap off to get access to the points/condenser. The points could be dirty, or not even making contact. I'd replace the condenser no matter HOW good it looked. A new rotor is a good idea too. We're talking maybe forty bucks worth of new parts, but once installed you KNOW that portion is okay.

If all else fails, there are a number of magneto repair shops advertising right here on the Stak. If you pull the mag to send it in for repair, make sure you have the instructions how to reinstall and time it to the engine!
 

nrp3

Registered
I pulled the white wire off with that in mind and it didn't produce any spark either. The rotor had a very loose fit on the shaft. I have done a limited amount of searching, so I dig some more through other posts.
 
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