JD 318 Onan B43G - Charging Problem

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JD 318 Onan B43G - Charging Problem

Brent Scheer Guys, I am really struggling with this tractor. I purchased off of ebay not running. I found a short under the battery tray, which was preventing the tractor from activating the starter. However, the Battery light has remained on through the other repairs and now that the engine has been rehabed, the battery light remains. It appears to be a 1983 or 1984 based on the serial number. the Battery is grounded through the fire wall and onto the left side of the engine directly to the head (not under the battery tray).

I have put a used Stator and now have a brand new stator on it. With the new Stator, I now am receiving 0V (Digital voltmeter + test probe to one side and - test probe to the other terminal of the stator). Ohms test on the new stator is .000 (basically, zero resitance) and approximately the same result on the old Stator as well. I do have 12V to the B+ Regulator terminal (middle terminal).

I can't get past the stator to check the regulator because I can't get 28V to 57V from the Stator. Could it be the flywheel? Am I missing something? I do not have a wiring diagram and have found A LOT of help from Dave's prior posts (God Bless Dave). But I still haven't made a breakthrough. Battery is in good shape and appears to hold a charge fine.

Email me the wiring diagrahm if you have one or tips, I am frustrated, but refuse to let this problem beat me.

Alan Hi Brent,
I sent you an e mail with the wiring diagram.
I have heard the stator won't make electicity if the magnets have fallen off the flywheel.

Brent Scheer thanks Alan, unforunately that means I have to pull the engine...again!

But if that fixes it, it is worth it.

Thanks for diagram.

Dave Brent - When you measure the voltage off the stator leads, are you disconnecting the leads (two outer positions) from the voltage regulator? If not, you should. Otherwise, your readings may be wrong. Tractor needs to be running at full throttle.

Also, you did not mention if you were attempting to read AC voltage or DC voltage off the stator leads. You need to check for AC voltage off the stator leads.

I always check each stator lead individually, tractor off, for continuity to ground. If you find any resistance, that's an indication of a short.

When checking the voltage output from the regulator, disconnect the middle wire from the regulator (stator leads reconnected). Run the tractor at full throttle. Now you need to check for DC voltage. Make sure to set the negative probe to a known ground point before touching to the middle terminal on the regulator. I usually rely on the engine block for the ground point. You should get at least 13.5 VDC.

Are you using a digital meter or an analog meter? A digital meter is more accurate. When you replaced with the new stator, did you also replace the pickup coil, or did you use the old one? - Dave

Brent Scheer I am using a Digital Volt Meter. Both leads unhooked and at full throttle. I only have the ability to read DC volts on my voltmeter. so I am reading using DC volts setting on voltmeter.

checked each lead with tractor off, zero resistance, appears to be no short.

Voltage at the regulator B+ terminal (middle) is the same as measured at the battery. To date, I have yet to get a higher reading.

What is the pickup coil? Where is it and what does it look like?

Thanks so much for your help!

Dave Brent - If your meter won't read AC volts, you are just chasing your tail on this one. Without knowing the output of the stator in AC voltage, you don't know what the real problem is, if any. You have to use the right tool to do the job. Don't mean to lecture, but it's pretty hard to help out, with partial information.

The pickup coil is located at the stator, but I realized your engine is a B43G, so it does not have one. Only electronic ignition P218G Onans have the pickup coil (ignition module). - Dave

Dave Brent - I re-read your original post. You may have damaged your meter when trying to read the voltage off the stator leads, if your meter only reads DC. Therefore, your readings on the regulator and battery may be inaccurate. - Dave
Brent Scheer Dave,
Not to proud to get a lecture. I have found I learn something new everyday...case in point.

I will get an AC voltmeter and charge on. Will keep you all posted.

Brent Scheer Got a new voltmeter that reads AC and DC. Had on 200V setting on AC and checked. Placed Pos lead from voltmeter to one AC terminal and Neg lead to the other AC terminal of the stator output. I now have a reading of between 36 and 40 V at full throttle. Seems OK. Reconnected both AC outputs to the regulator.

Onto the regulator, I placed voltmeter on 20V DC setting. Neg lead from voltmeter to neg terminal of battery and positive to the middle terminal on the regulator. Got Neg 15 V. I have another regulator, installed it on the 318, new reading is 2.22 V.

I think I need a new regulator? what do you guys think?

Brent Scheer Installed new regulator today, getting about .06V DC with Postive lead on middle terminal and neg lead on neg terminal of the battery?

Why won't this thing charge? please help

Brent Scheer SOLVED!

the regulator installed prior was purchased on Ebay and was junk! I splurged and bought the Onan regulator for $64 from Deere dealer and it solved it!


Thanks everyone. Lesson I learned is DO NOT purchase regulators off of Ebay. Spend the money and get the real thing.

dan I have a JD 318 with Onan B46G engine. I recently did an overahaul tractor running fine. Now it wont't start. Turns over but no spark? Has new regulator, battery, ignition switch and fuses. I am stumped. I put new plug wires on as well and still nothing. It turns over fine and I can see gas in the in-line filter. I layed the plug on the side of the engine and turned over - no spark - thoughts?

charles godin hi got the stator out of my onan 218g engine and clean it , the fly wheel was cake with fine dirt. would that have it not putting out a good reading of more that 12v at the middle terminal on a new regulator ? ,( doing the same as the old one did.) thinking of just getting a new stator save time. it not putting out like my other 316 with a 218g engine stator is. thank

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