2112 wrote:
The engine, in good standing, is good for 4KW+. If the generator head had issues such as a shorted winding, poor brushes or failing field, it just wouldn't create a 4KW load on the engine.
I almost hate to suggest this because I know someone is going to slap me for this but, to rule out fuel related issues, you can get a can of ether starter fluid such as below and when the engine starts to bog down, spray just the smallest mist you can create into the carb. If the engine 'wakes up' for a few seconds you know the problem is fuel related. I can't emphasize enough to be careful not to spray too much ether. While using ether, YOU become the carburetor. If it starts to run away, hit the kill switch.
Instead of starting Ether, try a spritz of Carb cleaner.. Carb cleaner will be a bit less violent than Ether. Your engine WILL thank you for that..
Typically these Chinese built engines are setup pretty darn lean and if it is a carb/fuel issue the OP would be having the engine "hunting" and would have to run the engine with partial to full choke just to keep running or smooth.
This should also be the same carb design as a Honda and this design is well known for main jet clogging resulting in engine hunting for fuel and partial choke to full choke to keep running.
The fix for that symptom is to remove the main jet and main jet tube and clean the tube and jet You remove fuel bowl and unscrew the main jet which is located in the center of the carb, (fuel bowl screws to this). Flat blade screw driver is required to remove jet and you will be doing this upside down. Once jet is loose it will fall out and a jet tube may also fall out.. That tube has multiple pin holes which often plug up and that is what needs cleaned.
For good videos you can YTube search for cleaning Honda clone carb cleaning.
I am fairly sure though it is not fuel related unless it is a stuck float and too rich but I suspect the OP would know that condition from all the black smelly soot produced from too much fuel..
I was also thinking that a shorted winding on the gen head could be potentially preloading the gen.
A miswired or shorted 120/240 Volt switch can also preload the gen head. The 120/240 switch essentially rewires the gen head, for 240V it places the two 120V windings in series.
For 120V only operation, it connects the two 120V windings in parallel.
You can try placing the switch in 240 mode and then add your loads and repeat your test. in 240V mode, your 15A outlets will become two separate 120V outputs so you will put one load in each of the 15A 120V receptacles. In 240V mode, you can only get 15A on each winding, as there is a 15A breaker on each 120V winding.
Additionally, the AVR is monitoring only one of the 120V windings so voltage regulation may not be as good if load is on the winding that the AVR is not on.
If the gen passes the 240V setting then you would need to check the gen head wiring to the switch and also verify the switch is wired correctly and also not bad.
Additionally this gen has a separate 12V DC winding, make sure the diode bridge is not shorted and you are getting 12+ volts at the connection (it is unregulated and unfiltered).
On edit..
Forgot to mention, in 240V mode, BOTH 120V windings MUST be the same voltage without a load. The reason they must be the same voltage is the fact that they are paralleled in the 120V only setting. If there is a mismatch (say a shorted winding) the bad winding will load down the good winding, in turn dropping the output voltage AND preloading the engine.
The 119 volt figure IS a bit low when unloaded (not sure if your measurement of this was unloaded or loaded), it should be closer to 125 if not a bit higher (can be as high as 130V and be within typical 120V voltage specs) and when loaded drop or sag some. This lower voltage is also making me think that there may be a shorted winding..
