MF65 intermittent charging

Boss Hog

Member
I have an MF 65 with a gas engine. Over the past couple of years I've battled getting it to charge. I can't seem to get it to do so consistently.

I tried replacing the voltage regulator about a year ago. It immediately started charging, and it kept charging for 3 or 4 months. Then it quit again.

I thought maybe I got a bad voltage regulator, so I replaced it again. It didn't charge after that.

So I tried flashing the field. (Used directions I found in a post here, but didn't save the link) When I started it up it was charging. For a while. Then it quit again.

I tried taking the belt off the generator and hooking a jumper cable to it. The generator spins like an electric motor. (Fairly slowly)

I tried cleaning the points on the voltage regulator. Didn't seem to make any difference.


I tried something else that has me puzzled. With the engine running, I jumped from the battery to the generator terminal furthest from the engine. It immediately started charging. But when I shut the engine off and re-start it the next day, it no longer charges.

I have no idea what's wrong or what to do next. Any suggestions?
 
On that Delco system set the throttle about 1/3, then GROUND the generator field terminal. If it shows charge, then regulator is at fault. It "controls" the amount of ground to control the charging rate. If it "motors" with twelve volts to the armature post with the belt off, generator is OK, it should turn on it's own slowly. Might also blow the dust off the brushes and holders to make sure they slide freely. If you still have the original regulator, remove the cover, file both point sets, then run a paper bill from your wallet to clean off any residue. I've found some originals will work again, unlike some of the across the pond regulators we see now.
 
Here's some interesting literature to look over.

Look on page 9. It talks about setting the point and air gap for the cutout relay. That sounds like your problem, the relay may be gaped too wide to pull in on it's own.

Also be sure the regulator base is grounded.
Delco Regulators
 
Well, I tried grounding the field terminal next. That did nothing.

As best as I can tell, the base of the voltage regulator is grounded.

So I took the cover of the regulator. Tried running the engine, and both sets of points were bouncing up and down. It wasn't showing a charge.

So I shut it off and tried bending the top arm down a bit. When I re-started the thing it was charging.

Maybe it's fixed? Will have to watch it a while and see how it does.

I appreciate the suggestions.
 

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