RV Generator Service and Repair in Chino, CA
An RV generator is the part of the coach you notice least until it is the part that fails first, and most failures trace back to sitting, not to age. McBride's RV Service and Paint in Chino is a Cummins Onan authorized service center, and we diagnose, service, and repair gas and diesel RV generators for Inland Empire motorhome owners. We have kept Southern California RVs powered since 1967.
Why does my motorhome generator shut off when the fuel tank is still a quarter full?
That is almost never a broken generator. The Onan set in most motorhomes pulls from the same fuel tank as the chassis, but its pickup tube is mounted higher than the engine's on purpose, so the genset starves and shuts down at roughly a quarter tank while the drivetrain still has fuel to reach a station. It is a designed safeguard that keeps a long night of air conditioning from stranding the coach on the freeway with an empty tank. Owners read it as a dying generator and bring the rig in for a repair it does not need. We confirm the behavior, check the pickup and the fuel-level sender, and tell you straight whether the set is fine. Knowing this one fact saves a lot of owners an unnecessary worry.
Why won't my Onan generator start or carry the air conditioners?
When a set genuinely will not run or cannot hold output, the cause usually traces back to sitting, not to age. A coach that parks for two or three months lets fuel turn to varnish in a gas Marquis or QG carburetor, draws moisture into the windings, and leans on a house battery that quietly sulfates in Chino heat. On the diesel Quiet Diesel sets in the bigger pushers, the enemy is different: running for hours at idle or under almost no load leaves unburned fuel and soot building in the exhaust, a condition called wet stacking that fouls the unit over time. Either way the set may fire in the yard and then fall on its face the moment two compressors and a microwave ask it for real current.
We diagnose every genset the same disciplined way. We verify clean fuel delivery, good ignition or injection, and a battery strong enough to spin it, then we put a true load on it the way your own air conditioners and converter will, and watch whether it holds. A unit that idles fine and collapses under load is telling you exactly where the fault lives, and the load bank is where that truth shows up rather than at a campsite with no shore power to fall back on.
What does Onan authorized generator service actually cover?
A motorhome generator is a small engine running on a maintenance schedule most owners never see, and skipping it is what turns a tune-up into a teardown. Scheduled service means oil and filter on the manufacturer interval, commonly around every 150 hours or once a year on the gas sets, plus the air filter, spark plug, spark arrestor, fuel system, and a run under genuine load to dry the windings and clear the exhaust. Because McBride's is a Cummins Onan authorized service center, we read the unit's stored fault codes, follow the factory intervals and torque specs, and fit the parts Onan specifies for your exact model rather than a generic substitute. We service the gas Marquis and QG sets and the diesel Quiet Diesel sets, which is the full range you find in Inland Empire coaches.
The cheapest thing you can do for the set costs nothing. Cummins Onan's own guidance is to exercise the generator about two hours a month under a real electrical load, not a quick idle in the driveway. For the diesel pushers especially, that monthly load run is what keeps wet stacking from ever starting.
Which Onan generators do you service?
We service the gas and diesel Onan sets that are actually installed in RVs, which is most of what is on the road. On the gas side that means the Cummins Onan QG series in the sizes commonly fitted to Class A and Class C coaches, along with the older Marquis, Emerald and MicroQuiet sets that are still running in coaches from the 1990s and 2000s. On the diesel side it means the Quiet Diesel sets fitted to diesel pushers. We also work on LP-fueled sets, where the failures tend to be regulator and fuel pressure rather than the fuel system problems that dominate gasoline sets.
The reason the model family matters is that it changes the likely fault. A carbureted gas set that sat for two seasons is a fuel system job before it is anything else. A diesel set that cranks and will not carry load is a fuel filter, air, or injection question. Diagnosing one like the other wastes your money. Tell us the model and the hour meter reading when you call and we will already know most of what we need to know.
Do you service Onan generators for Orange County RV owners?
Yes. Coaches come to us regularly from North Orange County, down the 57 and off the 91 from Brea, Placentia, Fullerton, Anaheim, Anaheim Hills and Yorba Linda, and we see Riverside and Corona owners come the other way on the 91 and the 15. Generator work is worth the drive for a specific reason: it is bench and bay work. A carburetor that needs to come off, be cleaned and be rebuilt, a slip ring and brush inspection, a load test that actually loads the set, or a diesel injection diagnosis are not driveway jobs. They need the coach in a bay, the right test equipment, and a technician who can put the set under real load and watch what it does.
That is also why owners at that distance tend to arrive with a generator that has already been looked at once. A set that "was fine and then died again after twenty minutes" almost always has a fuel delivery restriction that only shows up under sustained load. We test for the failure you actually have rather than replacing parts until the symptom moves.
Should you repair or replace an RV generator?
Most generator problems are a repair. A failed carb, a hardened fuel line, a tired set of plugs, a weak coil, a fouled spark arrestor, a marginal battery, or a control board is a repair, and you keep the set. Replacement is the call when a unit has gone hard internal — bent rod, scored cylinder, failed alternator end — and the cost of correcting the damage approaches the cost of a new genset, or when an old gas set is paired with a coach that now runs two high-draw roof airs and a residential fridge that the original output cannot carry. We open it up, show you what we found, lay out the numbers, and let you make the call.
Why does Inland Empire heat and storage time hurt RV generators?
Two local conditions shorten the life of a motorhome generator here. First, the heat. A set that sits all summer in Chino, Ontario, or Rancho Cucamonga bakes alongside the rest of the coach, and the heat cures gasket rubber, dries out fuel hoses, and breaks down the gasoline in the carb bowl long before any of it sees a load. Second, the long sit between trips. Inland Empire owners often store the rig for weeks at a time in a lot off the 60 or out toward Mira Loma, and a genset that never runs collects the same problems an unused lawn mower would, only on a much more expensive scale. Fuel goes stale, the house battery loses surface charge, varnish builds in jets, and the first warm-weekend run finds every one of those faults at once. The cure for both is the monthly load run we keep telling owners about, and it works.
What happens when you bring your RV in for generator work?
We open the set, read any stored fault codes on Onan units that support them, and run the unit through a real diagnostic: fuel, ignition or injection, governor, charging, exhaust, and a true load on the bench. You get a written estimate that names the parts and the labor before any work starts. Our estimates include a budget for parts, and the final price adjusts to the actual parts the unit turns out to need once it is open, with nothing done until you approve it. We make the repair with the Onan or OEM parts the set calls for, then run it under load to confirm it holds before the coach leaves. Before any work begins, we walk you out and show you what we found.
The McBride's difference
Family-owned since 1967, McBride's is a Cummins Onan authorized service center and a full RV shop. We service the generator alongside the chassis, the air conditioners the genset has to carry, the refrigerator on the same power bus, and the Aqua-Hot or water heater that runs alongside it, which matters because a failing set often shows itself first as one of those loads acting up. And we show you the problem before we fix it.
Frequently Asked Questions
How often should I run my motorhome generator?
About two hours a month under a real load, with the air conditioning or another genuine draw running rather than a quick no-load idle. For the diesel Quiet Diesel sets in larger coaches, that monthly load run is also what prevents wet stacking.
My generator shuts off but the tank is not empty. Is it broken?
Usually not. The genset fuel pickup is set higher than the chassis pickup so the unit stops at roughly a quarter tank to keep it from running the coach out of fuel. We confirm the fuel system is working as designed before anyone pays for a repair.
Do you service Onan Quiet Diesel generators?
Yes. As a Cummins Onan authorized service center we handle the diesel Quiet Diesel sets in the big pushers along with the gas Marquis and QG units in gas Class A and larger Class C coaches.
My generator runs but the air conditioner will not start. Is it the generator or the AC?
We separate the two with a load test. If the set cannot hold its rated output, the fault is in the generator or its fuel and governor. If it holds load cleanly, we look at the air conditioner instead.
How much does RV generator repair cost?
Routine service is the predictable, affordable end of the range; a carburetor rebuild or a full fuel-system cleanup on a set that sat a season is more, and a generator run into a hard internal failure is the bill everyone wants to avoid by servicing on schedule. Every estimate names a parts budget that adjusts to the actual parts your unit needs, and nothing is done until you approve the number.
Can I get chassis service while the generator is in the shop?
Yes, and most owners pair them. We service the Onan set and the Workhorse, Spartan, Ford, or Freightliner chassis in the same appointment, and you can see the chassis side on our RV chassis repair and maintenance page.
Why won't my Onan generator start after sitting all winter?
Nine times out of ten it is fuel. Modern gasoline breaks down and leaves varnish in the carburetor, and a set that sits for months without being exercised gums up the jets. The generator cranks, sometimes fires briefly, and will not stay running. It is a common repair and a preventable one.
How often should I run my RV generator?
Exercise it about once a month for a couple of hours with a real load on it, an air conditioner rather than a phone charger. That single habit prevents most of the fuel system failures we see, keeps the brushes and slip rings clean, and circulates oil. It costs you nothing and it is the best thing you can do for a generator you rely on.
My generator runs but shuts down after a few minutes. What is that?
Usually fuel delivery, sometimes overheating, and occasionally a low oil shutdown doing its job. The pattern of running and then quitting under load points at restriction somewhere between the tank and the carburetor or injectors. It is diagnosable, and it is worth diagnosing rather than guessing, because the parts on these sets are not cheap.
Do you service generators on travel trailers and fifth wheels, or only motorhomes?
Both, including portable and mounted sets on toy haulers, where the generator usually works harder than it does on a motorhome because it is running the coach rather than supplementing shore power.
Do you offer mobile RV generator service or house calls?
No. McBride's is an in-shop facility at 13788 Oaks Ave in Chino. Generator diagnosis and repair happens in our bays, where the set can be tested under load with the right equipment. We do not send technicians to your location or to a storage lot.
All of this work happens at our shop in Chino. We do not run mobile service and we do not make house calls. Here is why we are in-shop only.
Hear From Our Satisfied Customers
They are always professional, courteous and they have resolved any and every issue I had.
Our service areas
- Chino Hills
- Diamond Bar
- Montclair
- Yorba Linda
- Eastvale
- Ontario
- Norco
- Corona
- Rancho Cucamonga
- Pomona
- Walnut
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