What causes generators to stop producing power / voltage?
The most common cause of portable generators failing to produce electricity is from the loss of residual magnetism.
Generators work by moving electrical conductors through a magnetic field. Your generator does not have magnets. The magnetic field is created by taking some of the generator output voltage and converting it to DC and feeding it to a coil to make an electromagnet.
When there is a small amount of magnetism left over from the last time the generator was running, it is called residual magnetism. The little bit of magnetism is enough to produce a small amount of electricity. This small amount of electricity is needed to create an even stronger electromagnet. As the engine turns this magnet moving its electric field, through the stator windings, your generator produces even more power.
When the residual magnetism is lost, the generator will produce no power at start-up.
This residual magnetism can be lost naturally from not being used or from the load on your generator being connected when the generator is shut off.
It can also happen from running a generator with no load for too long.
Generators need to work and it helps maintain that residual magnetism.
When they are running, a load should be connected to it. It helps create an even stronger magnetic field. Before you shut it off, turn off the switch or breaker to disconnect the load.
If you shut off a generator with the load connected, it can essentially drains or demagnetize the electromagnet. So, try and avoid running out of fuel.
How to fix it:
There are a few methods of restoring a generator residual magnetism
12 Volt Generator Battery Method
Locate the voltage regulator for your generator. Unplug the two wires that connect to the generator brushes. Normally one is red and the other is black or white. Connect the black or white to the generator ground battery terminal. Plug in a light, turn on the generator breaker or switch and start the motor. Connect the battery +12 volts (red cable) to the red wire on the terminals you removed for three seconds. Remove your wires and replace the plug. The generator should now be producing power again.
Make sure you unplug the brush wires from the automatic voltage regulator or you will damage the regulator. Do not contact the voltage regulator or other wires as dangerous voltages may be present that can cause electric shock.
Electric Drill Method
Plug in an electric drill into the generator receptacle. If the drill is reversible, move the direction switch to the forward position. Start the generator. While depressing the trigger on the drill, spin the drill chuck in reverse direction. This will excite the field and the generator will now produce electricity. If spinning the chuck one direction does not work, try spinning the chuck in the other direction as you may have the reverse switch positioned backward.
Use caution not to get your hand or other materials caught in the chuck. As soon as the field is exited, the generator will produce power and the drill will turn on.
The reason this works is that the electric motor in the drill will act as a small generator when spun backward. The magnets in the drill's motor induce a voltage into the motor winding, which is fed back through the trigger cord and into the generator receptacle. From there it goes into the power winding of the stator. The voltage going through the power winding creates a magnetic field which is intensified due to the iron core of the stator laminations. The rotor intersects this magnetic field as it is spun past the power winding, thus inducing a voltage in the rotor winding. Once current flow is present in the rotor winding the rotor has been flashed.
If these instructions do not help you to restore generator output power, the next step is to replace the Automatic Voltage Regulator as it may be damaged.