Voltage Regulator

[KC9KAS 4,741]

Need assistance! 1977 Wheel Horse C-120 hydro.

I sold it to a young fellow last fall.

His dad said he put a new battery in it but it still failed to turn over to start.

I checked the only safety switch (with an ohm meter) and it is working correctly.

I checked all the wires (ohm meter) and they tested ok. I did come to the conclusion the 20 amp AMP gauge was bad.

I installed an old one that I had and it turned over and started right up.

I already had the voltage regulator wires disconnected and read 36 VAC from the stator.

When I attached the wires to the (fairly new) voltage regulator it would immediately cause the engine to sputter and die.

The voltage regulator is grounded directly to the negative post on the battery.

Once the wires were removed from the voltage regulator it would fire right back up!

I am at my wits end trying to figure this one out! Would a bad voltage regulator cause the engine to quit running? I may have to remove a voltage regulator from another known good machine and try it.

Anyone have any suggestions?

[Achto 27,508]

1 hour ago, KC9KAS said:

When I attached the wires to the (fairly new) voltage regulator it would immediately cause the engine to sputter and die.

The voltage regulator is grounded directly to the negative post on the battery.

Once the wires were removed from the voltage regulator it would fire right back up!

 

Does this tractor have a battery ignition coil? Did some one by chance change the ignition coil? Or run a new positive wire to the coil, possibly eliminating a resistor wire? If a coil that requires an external resistor is installed on a Kohler, it will work until the voltage to the battery starts to increase as the charging system starts to work. I fought this issue on my C-145, thought that the charging system was pulling it down but really it was the wrong coil. Engine would run for a short while & then it would bog down almost like it was under load and quit. It would run fine with the regulator unplugged.  I discovered that it had the wrong coil, installed a coil with an internal resistor and the tractor has ran great ever since.

Edited April 18, 2022 by Achto

[KC9KAS 4,741]

It ran and worked properly for several years before I sold it last fall. I know the family that I sold it to have not done anything to it.

I am just stumped on this one!

Edited April 18, 2022 by KC9KAS

[Achto 27,508]

5 minutes ago, KC9KAS said:

It ran and worked properly for several years before I sold it last fall.

 

If you have a coil laying around maybe try it on the tractor. There is a possibility that the original failed. 

[R Scheer 502]

Internal short in the voltage regulator may be drawing the voltage down, possibly causing the coil to not have enough voltage.  Just a thought.

 

Maybe check the voltage without the regulator connected, and with it connected.

[953 nut 55,092]

6 hours ago, KC9KAS said:

The voltage regulator is grounded directly to the negative post on the battery.

Once the wires were removed from the voltage regulator it would fire right back up!

Is the BODY of the regulator grounded to the negative post on the battery? There are two AC Voltage terminals on the regulator and one DC terminal. The DC terminal (disconnected from the regulator) should read battery voltage (12 volts DC) with the key in the on position but not running. Once you have confirmed this attach the wires to the regulator and see if the 12 volts is there. Could be an internal short in the regulatorpulling the voltage down.

[953 nut 55,092]

        been sitting all winter, check the wires for rodent damage.

[KC9KAS 4,741]

4 minutes ago, 953 nut said:

Is the BODY of the regulator grounded to the negative post on the battery?

Yes. I used one of the VR mounting holes.

 

3 minutes ago, 953 nut said:

been sitting all winter, check the wires for rodent damage.

It was stored inside an attached heated garage. No evidence of rodents.