How to correct e04 error cod or governor circuit on eu 6500is generator

Your governor is adjusted for the correct 60 hertz cycles. You may have lost residual voltage to excite the generator to produce ac. Being that it was sitting long time.
I could explain in lengthy conversations but you could just google : how to excite a generator and there is good write ups online as well if not better than what I could explain in detail.

check that you have the governor control rod on the butterfly lever of the carby connected correctly
it appears that the lever is at full throttle when you connected it and so the governor cannot pull it back to correct speed
if correct the throttle will be at full speed when stopped but will move with the go lever to slow when you manually push the gov lever

this sounds like a capasitor/resistor that is getting hot under load once it is switched off and cools down it works until it gets hot again similar to that of a cars ignition coil which will get hot and cut the vehicle out but once it cools it will start again.

make sure oil level is correct and viscosity. check governor arm for binding if loose and floppy internal mechanical damage. If you have the electronic governor actuator on your model then need to check for battery voltage on it, if present actuator bad, if not control board

on the governor arm itself,,,,there are a bunch of little holes drilled into the arm ,,,one end of the spring goes into usually the third hole from the shaft that the arm is hooked to,,another words the third hole away from the shaft,,,,then the other end of the spring goes to a stationary point to create a stationary base to the end of the spring for constant pressure..usually there is a deal sticking up for the spring to allow maximum movement of the spring without it touching anything.,,,hope it works,,,trial and error in this case is the best thing ,,hook it up WITHOUT stretching it too far,,if you stretch the spring to far then you WILL have to replace the spring!! be carefull on stretching it.

The transfer switch is responsible for starting / stopping the generator. Check your auto - start circuit. It is 2 wires that go between the genset and ATS. They are generally normally open. When the genset is to shut down this circuit needs to change state.

I am not familiar with your peice of equipment but from your description of the fault being Under Frequency it appears that generator governor is out of adjustment or the governor spring has brcome weak or broken and not allowing the engine to run at the correct speed to produce an output frequency within the allowable tolerance. Governor linkage could also be binding and not moving smoothly to respond properly to engine load conditions. Thoroughly check governor and throttle linkage for free and smooth operation and full range of movement.
Another cause could be that the engine is not getting sufficient fuel causing the governor to have the throttle wide open to try to get engine to run at its correctly governed speed but unable to do so because the engine is not developing enough horse power.

Take a close look at the governor and its associated springs. There should not be any play in the governor arm, springs should be taught when engine is off.

The governor spool may also be binding, but much harder to check since it is internal to the engine.

Start the generator, and watch the governor arm. When RPMs drop, you should see the arm move in an effort to open the throttle. Conversely, when the engine races, you should see the arm move in the opposite direction to try and close the throttle. Small movements of the governor are normal with a steady load. If you don't see the governor trying to correct engine speed, you likely just identified the culprit.

4 Things can cause this, 3 of which are related.

1) Governor arm is binding, or has slipped on the governor shaft. Check and reset if needed.

2) The "Load Detection" is not working correctly. Either it is not able to sense a load, or it won't disengage the solenoid.

3) Solenoid which moves the governor (for lower speed) has stuck due to dirt and grime in the housing

4) The linkage on the solenoid is binding due to dirt and grime.

The Econo Mode / IdleMatic / Whatever is actually hard on your appliances and tools. Nothing electric likes to be subjected to a low voltage at the wrong frequency, then be forced to tolerate a sudden change in frequency and voltage. Personally, I would find the pin that holds the solenoid linkage to the governor, and remove it, allowing you to remove the linkage altogether. Disconnect the electrical connector the solenoid, and just use the generator at full and proper speed.

what make ?