--- title: "RV Generator Repair and Service" url: "https://ocrv.vip/services/mechanical-systems/generator-repair" business: "OCRV Center" phone: "(949) 799-3387" address: "23281 La Palma Ave, Yorba Linda, CA 92887" serviceArea: "Lake Forest, Orange County, California" description: "Diagnosis and repair of gasoline, diesel and propane generators, including fuel delivery, control boards, load faults and scheduled service." --- # RV Generator Repair and Service in Lake Forest, CA Generator repair services the onboard power plant that supplies 120-volt current when a coach is away from shore power. It covers gasoline, diesel and propane fired units, including fuel delivery, ignition and control boards, brushes and slip rings, exhaust and mounting, plus scheduled service by run hours. Category: Mechanical and Electrical Systems Ballpark range: $400 to $8,500 and up, 2 to 35 hours Ranges are planning figures. The written estimate is produced after the vehicle is inspected at the shop. ## What owners notice first - Cranks but will not start after sitting through a storage season - Starts and runs for two minutes, then shuts down on its own - Runs but drops out when the second air conditioner is switched on - Surges or hunts audibly at idle instead of holding steady - Produces output at the generator but nothing reaches the coach panel - Black exhaust smoke, an oil film in the compartment, or a rattling mount ## Fault codes first, then the three things it needs Modern Onan and Cummins units flash fault codes at the start panel and store them in the controller. Reading those codes takes a minute and eliminates entire branches of the search. A code for low oil pressure, overspeed, over temperature or a lost ignition signal points directly at a subsystem and saves the hour it would take to arrive there by testing. Once codes are read, a generator is diagnosed on the same three requirements as any small engine: fuel of the right quality at the right pressure, spark or injection at the right time, and air with a clean path in and out. We check them in that order because fuel is the failure in the overwhelming majority of units that sat through a storage season. The fourth requirement is unique to a generator and gets tested separately: it has to make electricity. A unit that runs perfectly and produces nothing is an excitation, brush, slip ring or voltage regulator problem, and no amount of fuel system work will touch it. - Stored and flashing fault code retrieval from the controller - Fuel pressure and quality verified at the carburetor or injection pump - Ignition or injection timing and spark verification - Air intake, filter and exhaust restriction check - Output, excitation and voltage regulator testing as a separate stage ## Fuel delivery and the pickup tube problem Gasoline generators in motorhomes draw from a dedicated pickup tube in the chassis fuel tank that stops several inches above the bottom. That is deliberate, so the generator cannot strand you by using the last of the fuel, and it is also why a generator that will not run at a quarter tank is not necessarily faulty. The real fuel failures are varnished carburetors from ethanol blended fuel left standing, a failed fuel pump, a plugged filter, or a pickup line that has cracked and is pulling air. A pressure and volume test at the inlet distinguishes these quickly. Varnish is the single most common finding on a unit that sat in a Lake Forest storage lot over a season. Diesel units have their own pattern. Air in the supply line after a filter change, a lift pump that has lost prime, a return line restriction, or fuel that has grown biological contamination in a tank that sat half full. Diesel gensets are bled and pressure tested rather than assumed, and injectors are evaluated on their return volume rather than by replacing them as a set. - Fuel pressure and volume tested at the unit, not at the tank - Carburetor cleaning, rebuild or replacement on varnished gasoline units - Pickup tube and supply line integrity and air leak testing - Diesel bleed, prime and return volume evaluation - Propane regulator and lockoff testing on liquid propane units ## Load testing, output and the transfer handoff A generator that starts is not a generator that works. Output is measured at the unit with a load applied, and then measured again at the coach panel, because the two readings answer different questions. If the generator holds voltage and frequency at the unit but the panel sags, the transfer switch or the feeder is the problem. Load testing means running the unit to a meaningful percentage of its rating and holding it there. A four kilowatt unit that carries one air conditioner and drops out on the second is either down on power, restricted on fuel or air, or its governor is out of adjustment. Watching frequency while load is added tells you which, because a governor problem shows as a frequency drop before it shows as a voltage drop. Light loading is a maintenance issue in its own right. Generators that are only ever run with a single small load carbon up, wet stack on the diesel side, and develop the exact starting complaints that bring them in. Part of every service here includes a recommendation on exercise interval and load level for how the coach is actually used. ## Transfer switch behavior on the generator side The most common complaint that turns out not to be a generator is the coach that has no power while the generator runs perfectly. The transfer switch has a timing delay before it hands the load over, and when the delay relay fails or the contacts have pitted, the handoff never happens. Testing this means measuring at the generator side terminals of the switch, then at the output terminals, with the unit running and loaded. A switch that is present on the input and absent on the output has failed, and it is a far less expensive repair than the generator work that gets quoted when nobody checks. Older coaches sometimes carry a manual transfer arrangement or a separate breaker interlock instead of an automatic switch. Those get inspected too, along with the shore cord storage arrangement, since a cord left partially plugged is another reason a generator appears to make no power. ## Mounting, exhaust and the compartment itself A generator sits on isolators inside a compartment that has to bring cooling air in and push exhaust out, and the compartment is part of the machine. Collapsed isolator mounts let the unit vibrate against the slide tray, which cracks exhaust joints and loosens electrical connections over time. Exhaust integrity is a safety item and gets treated as one. Any leak upstream of the tailpipe puts combustion gas near the coach, and on a coach with a bedroom over the compartment that matters a great deal. We pressure check the system, replace cracked flex sections, and confirm the tailpipe extends past the body line as designed. Cooling air is the other half. A compartment with a blocked inlet louver or an exhaust path fouled with road debris will make the unit shut down on high temperature after twenty minutes, which owners consistently report as an electrical fault. Clearing and correcting the air path is often the entire repair. - Isolator mount and slide tray inspection and replacement - Exhaust joint, flex section and tailpipe integrity check - Cooling air inlet and outlet path clearance - Compartment sound insulation condition - Carbon monoxide detector verification inside the coach ## Scheduled service by run hours, not by calendar Generators are maintained on run hours from the meter, and most coaches that arrive with a starting complaint have never had a service performed against that number. Oil and filter, air filter, spark plugs on gasoline units, fuel filter, and valve lash adjustment on the interval the manufacturer specifies are what keep a unit reliable into its second decade. Valve lash in particular is skipped almost universally and it is the reason a well maintained looking generator gets progressively harder to start. Adjusting it is inexpensive relative to the running problems it prevents, and it is measured with a feeler gauge rather than estimated. For coaches stored between trips, the useful habit is a monthly exercise run under real load for a solid block of time rather than a brief no load run. Bring the run hour reading with you when you come in and we can tell you where you sit against the schedule for your specific unit. ## How the work runs 1. Code retrieval and history. Stored controller codes, run hours and service history are recorded first. The hour meter reading alone frequently explains the complaint before a tool comes out. 2. Static checks. Oil level and condition, filters, plugs, belt where fitted, mounts and exhaust are inspected cold. Fuel is drawn and assessed for varnish, water or biological growth. 3. Start and run evaluation. The unit is started with instruments attached. Cranking behavior, time to fire, frequency stability and voltage are recorded before and after warm up. 4. Load test. Load is applied in steps toward the unit rating while frequency, voltage and exhaust are watched. This is where a fuel restriction, a governor adjustment or a genuine loss of output separates itself. 5. Output path verification. Power is followed from the generator terminals through the transfer switch to the coach panel so a distribution fault is never mistaken for a generator fault. 6. Repair, service and re-test. Repairs are completed alongside any scheduled service that is due, then the unit is load tested again and the readings recorded on the invoice with the hour meter figure. ## Questions ### My generator sat all winter and now it will not start. What is it? Almost always fuel. Ethanol blended gasoline left in a carburetor for months leaves a varnish deposit that closes the small passages, and the unit cranks with good spark and good compression but never fires. The repair is a carburetor clean or rebuild, a fresh filter, and confirming the fuel in the tank is worth running. Diesel units that sat behave differently and usually need bleeding and a filter, sometimes with a fuel polish if the tank grew contamination. Either way the diagnosis takes far less time than the guessing does. ### Why does my generator run but the coach has no power? Check the transfer switch before you assume the generator is at fault. The switch has to sense generator output, wait out a delay, and physically move the load over. Failed delay relays and pitted contacts are common, and the symptom is exactly this: a healthy sounding generator and a dead coach. We measure at the input and output terminals of the switch with the unit running, and that one test settles it. It is a far smaller repair than most owners expect when they arrive. ### How often should I run the generator if the coach is in storage? Once a month for a solid block, and under real load rather than idling with nothing switched on. Running an air conditioner or an electric water heater element gives the unit enough load to reach proper operating temperature and burn off deposits. Diesel units especially suffer from chronic light loading, which produces unburnt fuel in the exhaust and a unit that gets progressively harder to start. A regular loaded exercise run prevents most of the failures we see on units brought in after a storage season. ### Can you service a generator that is mounted on a slide tray? Yes. Slide out trays are the normal arrangement on Class A coaches and we pull the unit out on the tray for access. What matters is that the tray rails, the isolator mounts and the flexible connections at the fuel, exhaust and electrical points are all in condition to allow it. On coaches where a previous repair left rigid connections in place of flexible ones, we correct that as part of the work, because a rigid connection on a sliding tray fails eventually and takes something more expensive with it. ### Is it worth repairing an older generator or should I replace it? It depends on what has failed and on the hour meter. Fuel system work, control boards, brushes, slip rings, mounts and exhaust are all sensible repairs on a unit with reasonable hours. A unit with very high hours that has lost compression or has a damaged stator is a different conversation, and at that point the replacement cost, the compartment fit and the transfer switch compatibility all get put on the table. We scope both paths so the comparison is on paper before you decide. --- All work is performed at the Yorba Linda facility. This business does not offer mobile, roadside or on-site service. It does not perform engine, transmission, drivetrain or DOT inspection work. Contact: (949) 799-3387 | info@ocrvcenter.com | https://ocrv.vip/contact