M generator problems

[matthies]

Having issues with the charging system. Genny motors just fine, ground the field stud and it charges great. Checked wiring and all good, went through John T's trouble shooting guide and still nothing.
Thought the regulator was bad so replaced that, still nothing. Polarizing has a good spark while fields are grounded and not running. While running no spark. Also while running, power on all terminals
of regulator. thanks

 

[Charlie M]

If you are deciding if it charges based on the amp gauge that could be bad. Others can comment better on the steps you have taken.

 

[John T]

If it charges if you ground the gennys FLD but NOT otherwise (says genny itself is okay) typically the VR doesnt have a good ground CHECK THAT,,,,,,,,,OR VR is bad,,,,,,,,,OR a wire is missing or theres a bad connection. If the VR's Cutout relay isnt closing as it should if genny is working, you can momentarily jump around that by jumping BAT to GEN/ARM maybe try that at fast RPM. The VR may be bad or again it needs a good ground to work and operate the Cutout Relay as well as regulate charge

How are you determining charge?? At fast RPM if working a 12 volt battery voltage should rise to at least 13 volts is it ??? If a battery is fully charged there will be little charging current flowing in and voltage not rise too much THATS THE VR'S JOB.

Insure a good VR ground, try BOTH by pass jumping the cutout relay BAT to GEN/ARM plus grounding the FLD as well Did I mention the VR needs a good ground lol

Take two aspirins and call me Monday at the office

John T

 

[Bob M]

Is the regulator base SOLIDLY grounded? If not the generator will not work.

I like to run a dedicated ground wire from the regulator base to a good ground on the engine...paint/corrosion where the regulator mounts will cause grounding problems.

Also make sure the flexible grounding strap between the regulator mounting base and the regulator itself is not broken!

Otherwise if you are reading batter voltage on all 4 regulator terminals with the engine stopped, your new regulator is bad. A good regulator should show battery voltage only at the B and L posts - the G and F posts should show 0 volts.

 

[matthies]

Regulator base was shined up on install of new reg, even grounded the gen field stud to it and had a jumper from the f term to coil mount, so grounds are good. Flexible ground good on old and new reg. Will check voltage at G&F tonite with engine off.

 

[matthies]

While running the ammeter is showing discharge, ground the fields and ammeter is 15-20 amps, had the rear light on and it was bright especially for 6V system. Think I had the batt and gen jumpered and no charge. Gonna need something stronger than aspirin.

 

[JonCT]

Hello, I had this same problem on my 39 M. It has a newly rebuilt generator and NOS cut out. The guy who rebuilt the generator told me that grounding is very important with this system. I pulled the brackets off back to the head and cleaned them to bare metal as well as the mounting tabs of the generator. I also ran a ground wire from the light switch body back to the battery ground. That fixed my issues and charged perfectly after that.