Generator safety — read this first.
- Carbon monoxide kills. Never run a generator with the exhaust pointed at an open window, door, slide seal, or a neighboring campsite, and never run it in a garage or enclosed storage bay — even briefly. Make sure your CO alarm works before any trip where you will rely on generator power.
- Let it cool before you touch anything. Exhaust and engine parts stay hot long after shutdown. Check oil and filters on a cold engine only.
- Fuel is a fire and health hazard. No smoking or open flame near the generator compartment, and do not refuel or open fuel lines on a hot engine.
- If you smell fuel, see a leak, or the generator runs but produces no power, stop and call a tech. Do not keep cranking or resetting breakers hoping it clears.
This guide covers built-in generators — the kind mounted in a compartment on motorhomes and some fifth wheels, most commonly gasoline or propane units from a small number of makers. Portable generators follow the same principles, but always follow the manual for your specific unit first. Intervals below are described in general terms on purpose: your manual's schedule for your model is the authority.
Why sitting is the main enemy
Generators are small engines, and small engines dislike storage more than use. Fuel left sitting in a carburetor can gum up tiny passages. Oil collects moisture and ages whether the engine runs or not. The starting battery — which on many rigs is the house battery or the chassis battery — self-discharges, so the first symptom of a neglected generator is often not the generator at all: a slow crank or a click. That is why our battery and converter basics guide is worth reading alongside this one — a generator that will not crank is a battery problem until proven otherwise.
The exercise habit
Manufacturers consistently recommend running a built-in generator regularly under load, even when you are not camping — commonly described as exercising it. The point of a loaded run is threefold: it circulates oil, it burns moisture out of the engine and generator end, and it keeps fuel moving through the system instead of sitting in it. Practical points:
- Run it under a real load for a sustained period — an air conditioner or a space heater on a mild day gives the engine actual work. Idling with nothing plugged in does much less. Follow your manual for the load and duration it recommends.
- Start it the way your manual describes — priming where your unit has a prime function, and giving the starter short attempts rather than one long crank. Repeated long cranking overheats the starter and drains the battery.
- Note how it behaves. A healthy unit starts promptly, settles to a steady speed, and carries a load without hunting or surging. Write down anything different — that description is gold for a tech later.
- If your rig is in storage without power, build the exercise run into your regular storage check rather than discovering a dead generator on departure day.
Fuel: the quiet failure
Most no-start and surging complaints that arrive after storage trace back to fuel. Gasoline ages, and fuel blended with ethanol can absorb moisture. Propane units avoid the stale-fuel problem but have their own version: a low tank, a regulator issue, or debris in the line can starve the engine the same way. What you can do as an owner is limited and mostly preventive:
- Keep the fuel supply your generator draws from in reasonable shape — on many motorhomes the generator draws from the main fuel tank and will stop by design when the tank gets low, so a generator that quits on a low tank may be working exactly as intended. Check the gauge before you assume a failure.
- If your manual recommends a fuel stabilizer for storage, use the type and amount it specifies, and run the generator long enough afterward for treated fuel to reach it.
- Never open fuel lines, drain a carburetor bowl, or change a fuel filter unless your manual shows it as an owner task and you are comfortable doing it — fuel work is a common place for a small problem to become a leak. Hand it to a tech if in doubt.
Oil, air filter, and the simple checks
The owner-level checks that matter most are basic, and they are the same ones a tech will ask about first:
- Oil level, on a cold, level engine. A generator parked on a slope reads wrong, so check it where the rig sits level. Low oil can trigger a protective shutdown on many units — an engine that starts, runs briefly, and stops is sometimes protecting itself, not failing. Use only the oil type and amount your manual specifies if you top up, and do not overfill.
- Air filter. A clogged filter starves the engine and can cause rough running under load. Many are owner-serviceable per the manual: remove, inspect, and replace if it is dirty or damaged. In dusty foothill and valley conditions — think summer trips out of Placerville, Auburn, or Grass Valley on dry roads — filters load up faster than owners expect.
- Look, listen, smell. Before a trip, look in the compartment for nests, chewed insulation, loose or corroded connections you can see without touching, and any sign of a fluid leak. Mud daubers and rodents treat a quiet generator compartment as housing; a nest blocking cooling airflow can overheat a unit that otherwise runs fine.
- Exhaust. Check that the exhaust pipe is intact and clear, and that nothing combustible sits near its outlet. A damaged exhaust is a CO and fire issue — do not run the unit until a tech has seen it.
Reading the symptoms
| What it does | Common directions to explore |
|---|---|
| Clicks or cranks slowly, or not at all | Starting battery charge and connections first — see the battery guide. The generator itself may be fine. |
| Cranks well but never catches | Fuel supply (tank level, propane supply), prime per the manual, stale fuel after storage. |
| Starts, runs a short while, then stops | Low oil shutdown, overheating from blocked airflow or a nest, or fuel starvation. Let it cool fully before one careful retry, then stop. |
| Runs but surges or hunts under load | Fuel quality after storage, clogged air filter, or a load that exceeds what the unit can carry. |
| Runs steadily but no power in the RV | The generator's own breaker, the transfer switch, and whether shore power behaves normally — a power-delivery problem, not necessarily an engine problem. Our electrical and plumbing page covers how a tech separates these. |
| Starts fine at home, fails at altitude or in heat | Thin air on Sierra trips and high ambient heat both reduce what a small engine can do. Mention the conditions when you call — they change the diagnosis. |
Managing load honestly
A generator can only carry so much at once. An air conditioner is the biggest single load most owners run, and its starting surge is the hardest moment. Stagger big loads: let the AC start and settle before adding a microwave or a high-draw appliance, and if the unit bogs down or a breaker trips when two big loads overlap, that is information, not necessarily a breakdown. Repeated tripping with a single, normal load is different — that belongs on a tech's list.
Stop and call a tech if you notice any of these
- Any fuel smell or visible fuel leak, or a damaged exhaust pipe.
- Repeated shutdowns after a full cool-down and one careful retry.
- Surging that persists with fresh fuel supply and a clean air filter.
- The engine runs but produces no power, or breakers trip repeatedly under a normal single load.
- Oil that is milky, metallic-looking, or far below the mark shortly after being topped up.
- Any fault code your unit displays that your manual directs to a technician.
- The next step would mean opening fuel lines, the carburetor, or electrical connections inside the unit. That is the line this guide does not cross.
What to tell the technician
Have ready: the generator make and model if you can read them off the unit, roughly how long it sat since its last loaded run, what it does now in sequence (crank, catch, run, stop), whether the problem changes under load, the fuel tank or propane level, and whether shore power works normally. Our guide to mobile RV repair costs in Northern California explains how the bill is built before you approve anything, and our AC troubleshooting guide is worth a look if the generator runs fine but the air conditioner still will not cool.
More owner guides
- RV battery & converter basics — the starting battery problem that looks like a generator problem.
- RV AC not cooling? Troubleshooting guide — including low-voltage and load problems on generator power.
- Winterizing your RV in Northern California — storage-season care, including fuel and battery decisions.
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Disclosure: NorCal RV Repair is an independent referral service, not a repair shop. We connect RV owners in Northern California with local independent mobile RV technicians. We do not perform repairs ourselves, and pricing and warranties are provided by the independent technician who does your work. This article is general educational information about common maintenance practice, not a substitute for your generator and RV manufacturers' instructions — always follow the manuals for your specific unit, and do not attempt any repair involving fuel lines, exhaust, or internal engine or electrical components.