HONDA GENERATOR PROBLEM : SEPARATE MOTOR AND GENERATOR CONNECTED BY V BELT. MOTOR HAS TWO MODULES UNDER FLYWHEEL. ONE LOOKS LIKE ARMATURE THAT POSSIBLY SUPPLIES PRIMARY CURRENT TO THE HIGH VOLTAGE COIL--- TO SPARKPLUG. THE ARMATURE COIL HAS 4 WIRES LEADING TO THE GENERATOR. PLEASE EXPLAIN THE FUNCTION OF THIS SETUP.

Question edited for better English.

Technical Information

Multiquip https://service.multiquip.com > pdfs > Honda_G... PDF
May 26, 2010 - Technicians will need to check the air gap between the ignition coil and flywheel during service inspections or after replacing the coil.

Honda Small Engine Ignition Armature Air Gaps

Outdoor Power Equipment Information https://outdoorpowerinfo.com > honda_fly_gap
The amount of clearance between the flywheel magnets and the ignition armature. The ignition armature is also referred to as ignition module, coil, laminate, ...

a GX390 Honda Motor but the used generator stator can be different cannot give more suggestions then measuring the circuitbreaker it can be broken the suggestion 60 mf capacitor can have trouble and electronic modul and bridge rectifier for some other dc connectors the coil diodes inside the stator. several options to go.

most armatures for gen sets are on a taper with a long bolt up the center from the rear of the armature

With center bolt and windings removed apply wd40 to area where engine crank enters the armature. Also apply wd40 into hole where center bolt was attached. Let oil work for a while. Use piece of hardwood against metal part of armature and give a solid hit with good size hammer being careful not to damage wiring. If it does not come loose with first hit apply more oil then hit opposite side of armature. If after second hit no joy, spray carb cleaner into areas where you used wd40 and let sit (carb cleaner will thin wd40 for better penetrating action) , then hammer armature (hardwood over metal part) one solid hit . Give oil time to work, crank is taper fit and could have some rust. Good luck

After testing for power and ground at the motor and switch I'd have a look at the BCM (body control module) or window module if it is separate. The BCMs of that generation are under the back seats and can easily get fluid spilled on them or just short out on their own.

no generator or alternator power generated by magnetic pulse[magneto]on the top of motor the fly wheel has magnetic inserts that pass thru a armature/coil causing a pulse sometimes the flywheel gets surface rust but that would also affect spark --check connections and test battery battery may not be holding charge or loose or corrosion in wiring can cause battery problem

unbolt from the engine then it will just pull of leaving the armature still in place on the crank shaft you may need to use a puller to get it moving

No, the plug would have nothing to do with that. It's really not even necessary. Be sure you have the air gap set correctly on the armature (coil). Loosen armature, pull it back on the screws and tighten. Turn flywheel to align magnets with legs on armature. Put a busness card between the armature and flywheel and loosen screws. The gap will close. Tighten screws and air gap is set. Hope that helps. Dwain

Sorry, I don;t have a solution but do you have a good coil from one of those you would like to sell?

Most engine driven welders have the charge armature located underneath the flywheel of the engine, but you need to check a couple of other things before you start tearing down the engine. Look for a small rectangular module on the blower housing of the engine, on a Kohler this is at the side, on an Onan it's at the top. This is the rectifier/charger module and it will have 3 wires, the 2 on the outside will be the AC from the armature, and the middle one is the battery charge positive. With the engine not running, use a DC voltmeter to measure the voltage between this middle tab and the engine block, you should see a voltage that's very nearly equal to the battery voltage. If you don't see a voltage there you may have either a blown fuse, a tripped circuit breaker, or a broken wire leading to the battery. On some welders the fuse or circut breaker is inside the welder cabinet on the bulkhead between the engine and the generator parts of the welder.
If you did see battery voltage at the charge terminal, start the engine, switch the voltmeter to measure AC voltage and measaure the voltage from one of the outside terminals to the other, you should see 15 volts or more (be careful not to short out anything). If you get a nice AC voltage, switch back to DC and measure the charge output again (engine block to middle tab), it should be greater than the battery voltage we measured before and it should be slowly getting greater, if not the rectifier/charger module is bad.
If you didn't see enough AC going into the module, stop the engine, disconnect the plug from the module and use an ohm meter to measure the resistance between the 2 outside wires that go back to the engine, something between 100 and 1500 ohms is good. If you measure an open circiut (OL on my meter) or if you measure 0 ohms, the armature is probably bad. You have to take the flywheel off the engine to see the armature. If you got a good restance reading but the voltage is still low you may have one or more broken magnets inside the flywheel, again you have to do some serious disassembly to see if that's the case.