RV CAMPING IS MUCH EASIER with a reliable generator. Whether your RV has a built-in generator or you’ve purchased a portable one for your trailer, you’re likely here because that reliability is in question. In this RV generator troubleshooting guide, we’ll walk through the most common reasons your generator won’t start, along with simple tests to help you isolate the problem and, hopefully, get it running again.
If these troubleshooting tips don’t remedy your RV generator issues, Camping World Certified RV Technicians are your best resource for further assistance.
Technician Tip: Troubleshooting recommendations will vary based on the generator manufacturer. Some of the most common RV generator brands include Cummins Onan, Honda, Yamaha, and Champion. Consult your owner’s manual for more troubleshooting tips.
Key Takeaways
- Start with Basics: Most generator issues stem from low fuel or oil, dead batteries, tripped breakers, or clogged air/fuel filters—check these before digging deeper.
- Test Critical Systems: Troubleshoot step-by-step—verify fuel delivery, battery voltage, wiring integrity, and starter motor function to pinpoint the cause of starting or power issues.
- Seek Professional Help for Complex Issues: If problems persist after basic checks or if you are dealing with fuel system leaks, damaged wiring, or internal electrical faults, consult a certified RV technician for safe and accurate diagnosis.
Why Does My RV Generator Not Start?
If your RV generator is not working, here are the most common causes:
- Lack of fuel and/or oil. Check your fuel supply and oil levels to ensure adequate levels of these essential fluids before further testing.
- Fuel delivery issues. Blocked fuel lines or fuel pump and/or filter issues could alter generator performance if an adequate fuel supply is confirmed.
- Lack of power. The generator isn’t getting enough power to perform the ignition sequence.
- Tripped breakers and/or broken or missing fuses could be the issue if your generator is running but you aren’t getting power to certain lights or appliances.
- Damaged or corroded wiring could cause starting issues and impair the generator’s ability to deliver power to RV systems.
- Insufficient ventilation may cause the generator to shut off if it detects dangerous exhaust levels.
- Starter motor issues. If it takes more than a few firing cycles for the motor to turn over, you may need to troubleshoot the generator’s starter motor or battery voltage.
Troubleshooting a Generator That Isn’t Starting
Smart generator troubleshooting begins with the simplest possible solutions and progresses to the more complex. All RV generators require diesel, propane, or unleaded fuel to power your internal systems, so let’s begin with fuel supply and system checks.
Check Fuel Supply and Essential Fluids
Any onboard or portable RV generator must have adequate fuel and oil to operate. Onboard generators typically pull from your motorhome’s fuel tank and run on the same fuel type as your RV’s engine (gas or diesel). Portable and built-in generators on towable campers can run on unleaded gasoline or propane, with hybrid or dual-fuel models that run on either.
Check the tank for whatever fuel your generator requires to ensure it’s at least one-quarter filled. While at it, use the dipstick to check your generator’s oil level. Most generators have a Low Oil Cut-Off Switch that interrupts the ignition cycle if the oil is low.
Read our tutorial on checking the oil and air filter on Honda portable generators.
Inspect Fuel Delivery System
It’s also possible that fuel isn’t reaching your generator due to issues with the delivery system. The common components of this system are the fuel tank, lines, pump, filter, carburetor, and injectors. Fuel is stored in the tank, drawn out by the pump, passes through the lines, and is delivered to the injectors. The filter removes contaminants before fuel enters the generator’s carburetor or injector system.
Potential issues with the fuel delivery system include filter blockages, pump/injector malfunctions, moisture in the fuel, and damaged lines. Checking the fuel filter for dirt or clogs is a possible DIY troubleshooting task, and it should be replaced at regular intervals according to the manufacturer. If there is no visible contamination in the filter, try blowing through it to ensure fuel can flow freely.
Fuel leaks caused by damaged lines are sometimes identifiable by spilled fuel, either beneath your RV or around a portable generator. However, because gasoline can evaporate quickly, there may not be puddles of liquid fuel to identify the leak. Watch for stains in the dust on or near fuel lines and check for cracks or cool spots to the touch along the fuel line caused by evaporative cooling.
Technician Tip: These micro leaks may also be allowing air to be sucked into the lines through all of the micro cracks instead of fuel from the tank. When such issues are found, replacing the entire fuel line rather than simply patching today’s leak is vital.
Damaged fuel lines and suspected issues with the fuel pump or injectors will require professional assistance. Because fuel is highly combustible, extreme caution should be taken if you suspect problems with your RV’s fuel delivery system.
Some RV service centers have mobile technicians who can travel to you and inspect the fuel delivery system. Research Good Sam’s RV ProCare Mobile Service program if you notice fuel leaks or otherwise suspect an issue with the fuel delivery system for your RV generator.
Test Power Input
In addition to fuel, built-in RV generators need power to start. So, your next step is to verify sufficient 12VDC power to crank your generator’s starter motor. Typically, your battery must have a minimum static voltage of 10.6 volts DC to start your RV generator. Depending on the ambient temperatures and the size of the generator, that may or may not be sufficient to crank the engine, but it is enough to try.
Technician Tip: Ideally, 11.4-12.6 VDC should easily spin up any generator for an ignition attempt. However, each manufacturer will have a specific minimum and maximum DC voltage range.
So, if you’ve verified ample fuel and eliminated potential fuel delivery issues, ensure your battery is connected and adequately charged. It can be easy to overlook a battery that has been disconnected for storage, especially if your RV has a battery disconnect switch. Check that the switch is in the correct position to supply power to your coach and ensure all cables are secure and corrosion-free.
If the battery isn’t disconnected, use a digital multimeter (set to DC voltage) to test your RV battery charge. If your battery has been discharged below 90% of its total capacity, charge it before attempting to start your generator again.
Technician Tip: Most portable generators do not require an external power source to start. Instead, they rely on a pull-start to turn the starter motor over. If you’re interested, there are onboard RV generator replacements with a pull-start feature.
Check Wiring
If the battery charge is adequate, but your generator still doesn’t start, you may have a wiring issue. Failed or disconnected wires will inhibit the battery from supplying sufficient power to start the generator. Excessive corrosion or damage can also compromise RV wiring.
Inspecting all generator wiring can be difficult. Some owner’s manuals offer a wiring diagram for assistance, but you may need to contact the manufacturer to learn more. If you find excessive debris in the system when inspecting wiring, you can use an air pump or canned air to clean the wiring for easier troubleshooting.
Technician Tip: The crimp on terminals and plastic Molex plugs can develop a light, almost invisible oxidation layer that reduces or prevents current flow. Something as simple as pulling the connector apart and back together a few times can restore function as the friction rubs them clean.
Evaluate Starter Motor
If you’ve verified sufficient battery voltage and you hear the RV generator clicking but it’s not starting, you may have a problem with the starter solenoid. This click usually indicates the solenoid is trying but failing to engage the starter motor. Lack of battery power can cause this, or a malfunctioning solenoid, improper grounding, or a faulty relay.
Technician Tip: The best test for the ground is to test the battery voltage at the battery directly from the positive to the negative terminal. Then place the negative lead on the starter solenoid ground lug while keeping the positive lead on the positive battery terminal. If there is more than a 5% voltage drop between the two tests, the ground path at the solenoid is suspect.
The “clicking, but not starting” symptom can also manifest when tripped breakers, blown or missing fuses, low oil or fuel, air filter clogs, or transfer switch issues are present. Eliminate as many of these potentials as possible before concluding that the problem is the solenoid or starter motor. If you’ve ruled out all other possibilities, have a Camping World Certified RV Technician inspect the generator’s starter motor.
It Starts, But Isn’t Supplying Power
Sometimes, you’ll get to a boondocking site, turn on your on board generator, and notice that you still don’t have power. The most common cause is an incomplete circuit, but we can also troubleshoot a few other issues.
Incomplete Circuit
In motorhomes, you must plug the shore power cord back into the outlet inside the cord’s compartment to complete the internal circuit. This is the same cord you’ll plug into a power pedestal at a campground, but if you fail to plug it back in when leaving camp, your generator will start and run, but it won’t power anything until the cord is plugged back into the internal outlet. Check this before proceeding with any additional RV generator troubleshooting.
Test Power Output
Let’s say your RV generator starts and runs, but does not produce power. You hear the generator engine hum, but nothing happens when you turn on AC appliances like your air conditioner or microwave.
In this case, check for tripped breakers or blown/missing fuses. Many built-in generators have a breaker on the generator itself, accessible from the outside, often by removing an access panel. Check that breaker and the breakers/fuses on your internal breaker panel. If no issues are apparent, you’ll need your multimeter again to test your generator’s power output. Ensure the RV isn’t plugged into shore power before proceeding.
To do so, set your multimeter to AC voltage and place one lead on a ground and the other on the generator’s output. It should be reading between 120 and 121 volts AC. Numerous issues, such as loose or damaged wiring, a faulty voltage regulator or capacitor, wiring errors, and generator overloading, could cause a low voltage reading. You may need professional assistance for more comprehensive testing.
Check Wiring
Failed, disconnected, corroded, or damaged wiring can also inhibit your generator from supplying power to various RV appliances. To test, you can shut down your generator and plug your RV into a properly-rated electrical service (30 or 50 amp). If all appliances and systems are working as expected, you can reasonably expect that the issue is with the generator or its wiring. This also assumes the generator is running and you’ve verified 120VAC output.
For easier wiring checks, contact your RV manufacturer for an electrical wiring diagram. You can also test individual appliances, lights, and control systems to isolate the issue. For example, if your air conditioner is working but your microwave isn’t, focus on the wiring and outlet for that specific appliance, ensuring it’s plugged in, and testing the outlet with a multimeter or a different appliance before assuming the generator is at fault or tracing the wiring back to the generator to clean and inspect along the way.
Technician Tip: Wiring inspections can be very complex. If you’ve eliminated the more basic problems, it’s best to have a Camping World Certified RV Technician inspect the system for the most complete, efficient repair possible.
Inspect the Exhaust System
If your generator starts but cuts off quickly, it could be experiencing a ventilation issue. Many RV generators have built-in safety features that shut them off when they aren’t receiving adequate air flow. The exhaust system must be free of leaks or blockages to function properly and ensure safe generator operation.
With built-in RV generators, the exhaust pipe must extend at least one inch beyond the RV’s exterior and remain at least six inches away from openings. The air intake and discharge must also be free of blockages. Inspect the exhaust system and use an air pump to remove debris.
What If My RV Generator Won’t Start After Sitting for a Long Time?
Most manufacturers recommend starting their generators at least once a month. They should run for a few minutes to warm up, and then for 15-20 minutes with a load, such as the air conditioner.
Suppose your RV has been in storage for the winter, and the generator won’t start after sitting. In that case, the most common causes are a dead RV battery, loose or incomplete battery connections, stale fuel, a clogged carburetor, or a dirty or worn spark plug. Here are some troubleshooting tips:
- Check all battery connections and recharge or replace batteries.
- Check the oil level and air filter. Low oil levels and air filter clogs can prevent the generator from starting.
- Drain and refill the fuel system. Some generator manufacturers recommend using a fuel stabilizer during RV winterization. If yours does and you skipped that step, you’ll likely need to drain and refill before re-testing your generator.
- Drain and clean the carburetor. In some cases, a rebuild may be required.
- Clean or replace the spark plug. A dirty or worn spark plug won’t ignite the fuel mixture.
How Long Do Generators Typically Last on an RV?
RV generator life spans are measured in hours and can range from as little as 2,000 hours to as long as 30,000 hours. On average, built-in RV generators last longer than portable generators. However, generator lifetimes will vary depending on the manufacturer, quality, and the level of maintenance exercised by the owner.
Use these guides for additional RV troubleshooting or help selecting a replacement RV generator:
- RV Generator Maintenance Guide
- How Do RV Generators Work?
- Portable Generator Safety
- What Size Generator Do I Need For My RV?
How can we improve this RV generator troubleshooting guide? Let us know in the comments below!
