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RV Generator Problems: How to Diagnose and Fix a No-Start Situation

There is a wide range of RV generator types from small portable gas to built in propane up to large diesel types. We have had them all and no matter the unit they all can have problems. Wear, tear or even non use can cause no start conditions and we have experienced many of them. Sadly its pretty common.

Today, we’re looking into how to identify the cause of your generator issues and how to troubleshoot them. Luckily engines and generation systems have a lot in common so we can take a look at some of the issues at large to try and help you out.

Electric Start RV Generators Not Turning Over

An electric start generator works with a battery-powered starter motor that engages with the generator’s engine when you activate the ignition key, push button, or switch. The alternative start type is hand crank which is started with a pull cord.

Motorhome power system
A built in generator alwas has a push button start.

Low Fuel Or Oil

Reason: Most built-in generators should stop running when the fuel level is too low to prevent the fuel tank from draining completely. This ensures that there is always enough fuel for RV to drive to a fuel station.

Additionally, many RV generators have built-in low oil cutoff switches that prevent them from starting if the oil is too low. The first thing you should check if your RV generator is not turning over is your fuel and oil level.

Solution: For your generator to successfully turn on, you will need to ensure your fuel tank is above a quarter full if built in. Additionally, check the oil level indicator on the generator to ensure your oil level is within the correct range

Bad Battery 

Reason: A standard cause for generators not turning over is insufficient battery power. This could be due to a low, discharged battery or a dead battery that you need to replace.

Solution: Start by checking the battery voltage. Try charging up the battery with another source if the voltage is low. If its been dead a while its probably time for a new battery.

Bad Wiring Connections

Reason: Corroded 12V battery terminals or wire connections will stop proper electrical conductivity to the start motor. Additionally, loose connections to the power line can lead to higher resistance that can cause them to heat and fail. We have had corroded terminals prevent our generator from starting.

Solution: To fix corroded terminals in a generator system, turn off the generator, and disconnect the batteries. ALWAYS disconnect the negative side first to minimize frame shorting with your wrench. With the batteries disconnected youcan also disconnect the and clean the terminals on the wires to the start motor using a wire brush or sandpaper. Next, apply a corrosion inhibitor and securely reconnect the terminals. 

For loose connections, disconnect the power and tighten all loose connections using appropriate tools. Next, inspect and replace damaged wires, apply lock washers if necessary, and then reconnect the generator to the power source. Reinstall positive first then negative.

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corroded generator start connections
These wires on the back of our diesel generator corroded and caused it not to start once, had to remove and clean them. ***Always be careful not to short battery wires when removing them and remove negative first***

Start Motor Malfunction

Reason: The starter motor is responsible for turning over the generator. If the start motor is faulty or the solenoid (a switch that controls electrical currents) fails, the generator won’t start.

Solution: To troubleshoot a start motor malfunction, check for power at the starter motor during a start attempt. If there’s power, it suggests a problem with the starter motor. In such cases, consider replacing the starter motor.

Control Panel Problems

Reason: If your RV generator is encountering control panel issues, it may be failing to send the start command or could have a fault code. Look for flashing lights on the control panel to better determine if this is the issue you are experiencing.

Solution: If you notice flashing lights, there are a few things you can do on the control panel to fix the issue. You will need to check the start/stop switch, the control panel fuses, and the signal from the control panel to determine the cause. If you can narrow it down to one part of the control panel, you may be able to replace that part. However, it may be necessary to completely replace the control panel to fix the issue.

Pro Tip: We crunched the numbers to determine How Long Can You Run an RV Generator Continuously?

RV Generator Cranking But Not Starting 

If a generator is cranking but not, it typically means that the engine is attempting to turn over but isn’t igniting. This can be due to a lack of one or more essential elements for combustion: fuel, air, the spark in a gasoline engine, and correct compression. The engine requires the right balance of these elements for combustion to occur and for the RV generator to start successfully.

Built in RV generator not starting
The first step to fixing your generator is diagnosing the source of the problem.

Low Fuel Or Oil

Reason: Like mentioned above some generators will not start if their fuel or oil is low. Most built-in generators will not start if the tank is below a quarter. Some generators will turn over but not fire up if the low oil cutoff is triggered.

Solution: Similarly to before, ensure the fuel tank is above a quarter full and check the oil level.

Fuel Issues

Reason: In addition to the level of fuel impacting how a generator starts, the quality of the fuel can also influence it. Has your generator been sitting for a while? Gasoline can go bad in 6 months! Your RV generator cranking without starting could be due to low fuel levels, contaminated fuel, a clogged fuel filter, or air bubbles in the fuel line.

Solution: This can be a tricky messy job and might require an engine mechanic if you are not confident. Staty be checking or fuel filters. You can then try bleeding the fuel system to remove any air. If you suspect bad fuel or notice contaminated, you will need to remove all the fuel. You can start by trying to add fresh fuel and purge the lines again if the tank was not full.

A carburetor might also need to be cleaned or rebuilt. Contamination and old fuel can gum up carburetors and require rebuilds.

Clogged Air Filters

Reason: When air filters clog, they obstruct the flow of air necessary for the combustion process. It creates an imbalance in the fuel-to-air ratio. This imbalance hinders the engine from receiving the optimal amount of oxygen for efficient combustion. These clogs result in difficulty starting the RV generator.

Solution: Start by removing and cleaning the existing air filters. If air filters have damage, replace them to improve the airflow necessary to start the generator.

RV generator cranking but not starting
Your RV generator is essential gear to keep the power in your rig running.

Spark (Ignition System) Issues (Not For Diesel)

Reason: When there is no spark in the ignition system (for gas and propane), the engine may crank but not start. This lack of spark can be due to issues with the spark plug connections or the overall condition of the spark plugs. You can identify this by observing if there are visible signs of wear or damage on the spark plugs and their connections.

Solution: Check the spark plug connections. Ensure they are securely attached and free from corrosion. If any spark plugs appear worn or damaged, replace them with new ones compatible with your generator. Additionally, verify that the ignition system is generating the correct spark during starting attempts. This involves observing for a visible spark at the spark plug gap or using a spark tester.

Pro Tip: Find out How to Build a RV Generator Exhaust Vent Pipe Stack for Your Camper to direct fumes away from your rig. 

The RV Generator Starts But No Power

If your generator kicks into action but leaves your appliances in the dark, several issues might be to blame. The automatic transfer switch (ATS) is responsible for seamlessly transferring the power source from the utility to the generator during an outage. It ensures a continuous and reliable power supply. If your ATS isn’t working correctly, the switch will fail to transfer power during an outage. You may need to repair or replace this switch.

RV generator
Generator issues may be a sign of larger engine issues.

Additionally, check the surge protector to ensure it allows power and inspect for neutral ground bond issues. Examine the generator panel for tripped breakers and reset them if necessary. You will also want to inspect the generator panel for tripped breakers and reset them if you need to.

Lastly, check for overload errors. These errors are our generator saying, “I can’t handle too much at once!” It might need a break. Look for anything that might use ample power and turn it off for a while. This helps your generator restart and keeps things running smoothly.

Pro Tip: If you have a Cummins Onan 10000 QD Generator, we shared how to do maintenance on it.

Larger Problems May Require Engine Repair

If you’ve tried troubleshooting your RV generator and have been unsuccessful, you might have larger engine issues. Problems with your carburetor, fuel injection, or engine’s compression system may be preventing the generator from running correctly. Unless you are a skilled mechanic, you will likely need to visit an expert for repair.

Have you ever had to troubleshoot your RV generator? Tell us the cause of your issue in the comments!


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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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