Wednesday, February 8, 2023


RV generator cannot carry a load


Dear Gary,
I read your column with much interest and one question regarding inexpensive water heater bypass valves caught my attention as I had a similar problem with my fifth-wheel. In my unit the hot water pressure was very low and flow was slow but the cold water was full bore at all taps.

Living here in Calgary, I had stored my unit for a lengthy period in a winterized condition and that was exacerbated by a delay. I now have an older Rialta and until this year all was fine. Now the generator will start and run with no problem and I can turn on low-load lighting without trouble, but as soon as a load is placed on it like the air conditioning or microwave, it quits right away. Any ideas for a fix? —Hank G.

Dear Hank,
Depending on the number of hours on the generator and how old it is, it just may be time for a set-up/tune-up. All RV power plants require regularly scheduled maintenance. Adjustments to the carburetor and possibly the governor may be in order. A certified RV service technician can quickly diagnose the generator by connecting it to a device called a load bank. RV generators cannot be tuned or set-up by ear and I caution the service technicians I teach that every mechanical adjustment on the generator has a direct electrical consequence.

Unfortunately, this one is better left to a pro technician because of the specialized equipment necessary to diagnose it. No-load and full-load voltages and frequencies must be within spec for the generator to carry a rated load.

You can rule out a fuel issue by inspecting the fuel line from the tank connection to the generator connection. Old rubber fuel hoses can crack and begin sucking air, which could lead to operational ills when a load is applied. You might also try running the generator from a separate fuel source then applying the load. If it quits again, you’ll know the problem is in the generator and not the fuel supply.


Read more from Gary Bunzer at the See Gary’s videos about RV repair and maintenance.

Previously published in January 2017.

RVT776; ##RVT877


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4 years ago

Gary, I’d say that is a really good answer. You covered everything. Leave it to some one who has the tools once you are sure it is not the gas connection.

6 years ago

It may be as simple as the inverter/charger is taking ALL that the generator can produce.. Then, when the Microwave is turned-on, the generator can’t keep up, and the RPM drops, causing the generator controller to shut it down. Some/most of the inverter/chargers have, what they call power-sharing, so that the charger will not exceed a certain load, leaving some amount of capacity (usually user-selectable) for other loads.

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