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JohnF2015
JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1107
Experience:  Owner/Service Technician at S & J Small Engines
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I have a 12HP01 engine. it has a wiring problem, the fuse

Customer Question

I have a 12HP(###) ###-####01 engine. it has a wiring problem, the fuse from the stator keeps blowing out.
Submitted: 1 year ago.
Category: Small Engine
Customer: replied 1 year ago.
this system is basic, a stator, starter, solenoid, switch, battery.
Expert:  JohnF2015 replied 1 year ago.

Hi, my name is***** will be assisting you.

Can you tell me more about when the fuse blows? Does it blow as soon as you turn the key on? Only after having run for a while? Only after you have done something specific?

Customer: replied 1 year ago.
not sure with out buying smaller fuses, it was blown every time I looked at it. I put a 20 amp. in and it wont blow but with the switch on the stator will smoke.
Expert:  JohnF2015 replied 1 year ago.

So, if you put a 20 amp fuse it is doesn't blow but the stator smokes.

This tells me that the stator is shorted out or the rectifier in the stator wiring is bad which is causing your problem. Do you have a voltmeter?

Customer: replied 1 year ago.
I do
Customer: replied 1 year ago.
I did change the stator with a used one
Expert:  JohnF2015 replied 1 year ago.

On your stator, how many wire(s) are coming from it? What color are the wire(s)?

Customer: replied 1 year ago.
one red wire. with the engine running the wire to the meter and ground I get .03 volts
Expert:  JohnF2015 replied 1 year ago.

If you check the wire with the engine off and go from the wire to a ground what kind of reading do you get if any?

Customer: replied 1 year ago.
0 ohms'
Expert:  JohnF2015 replied 1 year ago.

When does the stator begin to smoke with the 20 amp fuse in the system? Immediately after turning the key on or just when the engine is running?

Customer: replied 1 year ago.
with the key on and not running it will smoke in about a minute
Customer: replied 1 year ago.
I should say immediately after turning the key on visible smoke in less than a minute
Expert:  JohnF2015 replied 1 year ago.

That tells me that the rectifier is bad in the wiring which is allowing for battery voltage to be feed back into the stator which is causing the stator to smoke and the fuses to blow when using small amperage fuses. By installing the 20 amp fuse it will just take longer to blow it, but it will eventually blow.

Customer: replied 1 year ago.
this system doesn't have a rectifier that I can see
Expert:  JohnF2015 replied 1 year ago.

Can you tell me what the stator plugs into? Is it going to a regulator(2" X 2" box) or just back to a single wire?

Expert:  JohnF2015 replied 1 year ago.

If no box then it has a diode in the stator wiring just about an 1 1/2" up from the connector on the stator wire.

Expert:  JohnF2015 replied 1 year ago.

Is your stator a full circle or half?

Customer: replied 1 year ago.
the red wire goes straight to the solenoid. no diode. the stator is a half.
Expert:  JohnF2015 replied 1 year ago.

It has to have a diode in order to keep the battery voltage from back feeding into the stator and smoking the stator. At this point you stator is no good because you indicated that it only has .03 VDC output with the engine running(it should have between 14 - 15 VDC). You have to install a diode in the stator wire between the solenoid and the stator in order to prevent back feeding of the battery voltage to the stator.

Expert:  JohnF2015 replied 1 year ago.

Are you certain that you don't have a diode in your stator wire. It would be cover with a short piece of shrink wrap usually black which can be split open to reveal the diode.

Customer: replied 1 year ago.
nearly certain. sounds like I have to pull the cover again anyway
Expert:  JohnF2015 replied 1 year ago.

Yes, based on the information that you have provided to me so far. You will most certainly have to replace the stator again. Make certain that the replacement has a diode in the wiring otherwise it will do the same thing.

Thank you it has been a pleasure to assist you.

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Customer: replied 1 year ago.
There is shrink wrap on the stator wire
Expert:  JohnF2015 replied 1 year ago.

That short piece of shrink wrap is covering the diode. Based on what you are telling me the diode has to be bad on this stator. You could try to just replace the diode but once the diode goes bad it normally will cook the stator because it gets so hot from voltage feeding backwards into it.

Customer: replied 1 year ago.
I was wrong, there is no shrink wrap or diode,
Expert:  JohnF2015 replied 1 year ago.

Then this stator has to be plugged into a voltage regulator/rectifier otherwise it will back feed battery voltage into the stator and damage or smoke it. If allowed to back feed too long it will actually melt the windings of the stator.