Straightened out a "won't start" inverter generator today. It's a generator we bought specifically to loan out to the wife's sister. She is dependent on an oxygen contentrator, which means a power outage can become a big deal & there was no generator at her place.
We bought it a few years back when an ice storm had power out county wide. It is small enough for portability (49 lb.) but big enough to run her equipment (2K starting 1.6K running).
I recently heard that the last few times they tried to use it, it wouldn't run. Pretty sure they had ignored my suggestions for regular exercise. No knowledge of when it was last fueled or what was used. A couple of folks there said they would look at it, but nothing came of it.
I finally asked the wife bring it home after her next visit. First thing I did was to pump out the old gas. The gallon jug in the pic is what I pumped out.
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I added a few ounces of marine grade Sea Foam to the pumped empty tank & pulled the starter a half dozen times, which actually got it to fire. I then added few onces of my fresh treated gas to probably get to a 50/50 mix. At this point it starts & runs, but does not appear to be "full throttle" even with "eco mode" off.
At this point it would not take a load without dying. I let it sit, then run a bit, then repeat.
After a bit more run time I started gradually introducing a load. I'd use the switch on a hot air gun to add a 750w load, but remove it before the engine died, then repeat. Did that until it would not die under the load. I did the same thing with the 1500w setting until it could carry that.
I think the load based throttle linkage was just sticky until it was exercized a bit. Eventually it got to where it could go from no-load "eco mode" to a 1500w load without dying.
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I added a bit more gas and let it run an hour carrying 1500w, then removed the load & shut off the fuel valve to let it run out the fuel bowl contents. Once cool I filled it with my treated gas.
It should be good to go back.