MF-12 charging circuit

[MatadorND]

I recently repatriated my MF-12 and it is running great but the charging gauge indicates it is not charging. Does anyone have a diagram of the charging circuit?

I did notice that there is a black wire with an inline fuse that has no fuse in it connected to the voltage regulator. Could this be the issue?

 

[Bob]

"I did notice that there is a black wire with an inline fuse that has no fuse in it connected to the voltage regulator. Could this be the issue? "

NAW.. for Pete's sakes WHAT would make you think they put a functioning fuse in that wire for a reason?

Just leave the holder empty (especially if you don't want the charging system to work)!

 

[MatadorND]

Thanks for the smart aleck reply confirming that the fused wire is part of the charging circuit. I did not know what the wire was for. For all I knew it enabled the regulator when the key was on or something.

I did check the voltage at the regulator side of the fuse holder and it reads 19+V at WOT. I am still not seeing charging so I am suspecting a poor connection at either the ignition switch or the battery. I will update when I get a chance to mess with it tomorrow.

What is worrying me is that the voltage measured at the battery is actually lower by about .2V at WOT than it is at idle or off.

Would an 8A fuse be appropriate? That is what I put in and it didn't blow, but in my ignorance that might be too big.

 

[Bob]

What engine's in there, Tecumseh 12HP?

Under-flywheel alternator or starter-generator charging setup?

 

[MatadorND]

It is the Tecumseh 12HP engine, and to be honest I haven"t dug in enough to identify the alternator yet. It has the square green starter with one wire going to it if that helps.

I did measure charging voltage at the connector on the ignition switch, and that measures 15+ volts at the same time the voltage at the battery is 12.4V . This makes me suspect a resistive switch or wire. Unfortunately I have just had a few minutes at a time to look at it so far so I haven"t done any serious trouble shooting.

My next step will probably be to disconnect the ignition switch and figure out the switching scheme and check for resistance, then to check resistance in the wires and other connectors.

Seeing the 15V at the switch during charging does give me hope that it will be a low dollar fix.

The ignition switch has four terminals, three in a connector and the charging wire seperate. I am assuming that the three in the connector connect to battery, ignition and starter solenoid, but I will track that down positively when I have a bit of time.

I have ordered a manual, hopefully that will have an electrical diagram.

Do you have a tip to identify whether it is starter/generator or internal alternator?

Thanks again for all your advices.