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RV Generator Repair: A Complete Guide

Published on December 4th, 2023 by Kendall Jennings

Man inspecting motorhome generator at rear of motorhome - RV generator repair

A Guide to Taking Care of Your RV Generator

Your onboard generator is a lifeline for your RV. Being familiar with RV generator repair ensures your generator is ready when you need it. RV generators are workhorses that provide power when you need it. Often we take for granted that it’s there ready to work whenever called for.

If maintained properly, RV generators are pretty reliable and can go forever without repairs. When something does go wrong, however, waiting for repairs can quickly ruin a trip. RV generator repair should be on your list of things to learn if you have an onboard generator. One good thing about RV generators is that there is one manufacturer that provides the majority of onboard generators. There are also only a few models so much of the information will apply across the board.

Onan Onboard RV Generators

When you open your generator access door you will most likely see a green Onan generator. Onan is a Cummings-owned company with close to a century of reliable generator production. All industries from marine to agriculture and of course automotive rely on Cummings for dependable electric power.

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The heart of RV manufacturing in the United States is Elkville ID, and this is where Onan RV generators are built. Working side by side with all RV manufacturers allows Onan to have its hand on the heartbeat of the RV industry. Known throughout the industry as quality-built, dependable generators, any brand regardless of quality can and will have problems at some point. Many of these issues can be dealt with by RV owners with some knowledge of RV generator repair.

Common RV Generator Repair Issues

RV generators are, for the most part, pretty basic as far as engines go. With regular maintenance, they should be mostly trouble-free. The simple design also means most repairs are also fairly easy to perform. Since all RV generators are very similar, most will have the same issues when they do arise. Here are the most common RV generator repairs you may face.

The generator won’t Start

When you need your generator, you usually really need it! Often generators aren’t used regularly so when we go to fire them up and it doesn’t start we are surprised. Your car starts every day, multiple times most days, so we have come to just expect that when we turn a key or push a button an engine roars to life.

Most RV generators operate on the same fuel tank as your RV. As a safety mechanism, many have a shut-off to prevent your generator from running your RV out of fuel. If your fuel level gets to the set level, let’s say 1/4 of a tank it shuts off. You many need need RV generator repair…only more fuel! If your RV is at or below this level the generator likely won’t start. The wires and connections vibrate while the RV is moving and while the generator is running. A no start may be as simple as a loose connection. Checking the connections is an easy, free way to possibly fix a no-start.

When it comes to mechanical issues there are three main places to look. The spark plug, the fuel filter, and the fuel pump. The spark plug and fuel filter are easy to check, cheap to buy, and easy to replace. Most fuel pumps are reasonably priced but it is more costly than a filter and more work to replace so check the filter first.

Starts But Doesn’t Stay Running

Just because your generator starts every time doesn’t mean you won’t have any RV generator repair in the future. A generator that stalls after starting is equally as frustrating as one that doesn’t start at all. Fuel delivery problems or air-fuel ratio are the main reason for stalls. A dirty carburetor is a common culprit that causes generators to stall out after starting. If your generator hasn’t run in a while the carburetor may need a cleaning. A generator that does run regularly will also benefit from a carb cleaning every few seasons.

If your generator is getting fuel that is dirty or old, it will have a difficult time burning it. Fuel becomes contaminated with water when it sits. Water or dirt and debris will both negatively affect your fuel system. To operate properly, you need clean fuel at a certain pressure and a measured amount of air to mix with that fuel. If the airflow to your generator is restricted, the air-fuel ratio is off and you will likely have limited run time before the generator shuts down, necessitating an RV generator repair.

A low oil shut-off switch may also be causing your gen to stop running. A safety feature to prevent major damage should the oil level get too low, is automatically cutting power to the gen. You may just need oil to get back up and running. A simple spring adjustment may also be the fix you need. RV onboard generators have a frequency adjustment in the form of a spring that adjusts left and right as well as a tension adjustment to keep it in place. Referer to your manual for settings and ensure the tension is set to hold your adjustment.

Runs But Doesn’t Produce Electricity

Perhaps your generator starts and continues running but it’s just making noise and burning fuel, not producing power. That’s right, just because the generator is running doesn’t mean it’s producing electricity. In order to produce electricity for your RV, your generator must be running properly along with transferring that electricity to the RV. If you are not receiving power in your RV the first simple fix is the check your fuses and breakers. You can spend a lot of time troubleshooting for nothing if you simply have a bad fuse or breaker. It can be frustrating to discover that’s all it is, but it is an easy RV generator repair.

In addition to the breakers in the fuse panel inside your RV, most generators will have a circuit breaker located at the generator itself. This can be hidden in the generator compartment so search around for it, it’s there somewhere. There are also a couple of electrical connections to check. The main shore power cord may have come loose so check that it is secure. On some older RVs, the main power to the generator has also been plugged into the side of the gen. Newer models usually are hard-wired but if yours isn’t this could be your solution.

Preventative Maintenance

As with anything, the best way to prevent repairs is with regularly scheduled maintenance. Your RV generator is the second engine in your RV. It requires the same attention as the RVs drive engine. Regular oil and filter changes are key to longevity. Both services are easy to perform and the parts required are a fraction of the cost of expensive repairs. For most RVers, a biannual service is all that is needed to keep your RV generator running problem-free. Have a generator maintenance kit on hand so you are ready to go when your generator requires a tune-up. Taking a few minutes to do a visual check of your generator can find potential problems. Looking for loose connections, hoses, oil leaks, and anything that looks or sounds irregular can catch issues before they become pricey repair bills.


Becoming familiar with your onboard generator will allow you to know when something looks or sounds wrong. If maintained and repaired as needed, your RV generator will provide electric power for your RV for years.

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1 thought on “RV Generator Repair: A Complete Guide”

  1. We have an onboard Onan. For many years, if we overloaded it, we’d hear the generator conk out. Then on one trip, we must have overloaded it again. Only this time all the electric went out, and the generator was still running. I stressed thinking I might have blown a big component feeding A/C to the RV. I had already checked all my breaker panels. Finally pulled out Generator book and found that there is the breaker on the generator. Mine was like behind some metal, hard to see. Anyway, that fixed the proble,

    Reply

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