Onboard Systems
Generator Repair and Overhaul: Cost, Hours and Process in Hacienda Heights
Generator repair and overhaul diagnoses and repairs a house generator that will not start, will not hold load or has thrown a fault code. Scope runs from a gummed carburetor and a failed control board through a top end overhaul. The chassis engine is a different machine and is not part of this work.
What brings this in
- Cranks strongly and never fires, which usually points at fuel rather than ignition
- Starts, runs thirty seconds to two minutes, then shuts down on its own
- Will not crank at all and the start solenoid is silent
- Runs but produces no output voltage at its own terminals
- Surging or hunting that worsens as load increases
- A blinking fault code at the coach panel or the unit itself
- Black smoke and a strong fuel smell at startup on a gas unit
- Heavy vibration or a new mechanical knock that was not there last season
This job, by the numbers
$400 to $8,500 plus
2 to 35 plus hours
In depth diagnostic, 1 hour at $285. One hour minimum. Credited to an authorized repair.
Parts and assemblies we work with
Onan, Cummins, Kohler, Generac, Champion
Start with fuel, because it is usually fuel
A generator that cranks strongly and never fires is a fuel problem far more often than an ignition problem. Gasoline left in a carburetor for a year varnishes the passages, and the pilot circuit is small enough that a trace of varnish closes it. That single failure accounts for a large share of the units that arrive here declared dead.
On diesel units the equivalent is air in the fuel system, a clogged filter or a lift pump that has lost prime after a long sit. Same story, different mechanism: the unit is mechanically sound and the fuel is not arriving.
The reason this matters for your invoice is that a carburetor rebuild or a fuel system service is at the bottom of the band on this page, while an overhaul is at the top. Diagnosing in the correct order is the difference, and a shop that starts by quoting a rebuild has skipped the cheap answers.
- Varnished carburetor passages after a long sit with gasoline in the bowl
- Clogged fuel filter or a lift pump that lost prime on a diesel unit
- Failed fuel pump or a pinched or cracked supply line
- Ignition coil, plug or module failure on a gas unit
- Low oil pressure shutdown, which mimics a fuel starvation shutdown
- Control board fault or a corroded harness connector at the unit
Runs and then shuts down, which is a protection circuit doing its job
A unit that starts and drops out after thirty seconds to two minutes is normally being shut down deliberately by its own protection, not failing randomly. Low oil pressure, high temperature and overcrank are the usual triggers, and the fault code at the panel or the blink pattern at the unit identifies which.
Low oil pressure is the most common and the most consequential, because continuing to crank a unit that keeps shutting down for oil pressure is how a cheap repair becomes an overhaul. If your generator does this, stop starting it.
The second pattern is a thermal shutdown from blocked cooling airflow. A generator bay with a rodent nest, a compressed sound insulation panel or a partially blocked intake overheats within minutes. That is a cleaning and airflow repair, not a mechanical one, and it is a satisfying outcome to deliver.
When an overhaul makes sense, and what it costs
The band on this page is wide and open ended for a reason. A carburetor service is a few hours. A control board and a harness repair is more. A top end overhaul with valves, rings and a bearing is 20 to 35 plus hours at the posted mechanical and electrical rate of $260 per hour, with control board and winding lead times of 10 to 25 business days.
The decision usually comes down to hours on the meter against the cost of a new unit. A generator with 4,000 hours and a burned valve is at end of service and an overhaul is money spent on the parts that did not fail yet. A unit with 900 hours and a clear single fault is worth repairing without hesitation. We give you the hour count and both numbers and let you decide.
Diagnosis is the in depth diagnostic tier at one hour and $285, credited against an authorized repair. That hour buys a fault code read, a fuel and ignition check, a compression reading where indicated and a load test. It is the hour that decides whether this is a $600 job or a $6,000 job.
Scope
What this line item does not include
- Chassis engine rebuild, transmission rebuild and drivetrain work are outside what this facility performs.
- We do not repair generators at a customer location. Fault isolation requires a load bank.
- Portable standalone generators are not coach mounted equipment and are outside this scope.
Being explicit about the boundary is faster than discovering it at pickup. If the work you need sits outside this line item we will say so at intake and point you at the right one.
Questions
Generator Repair and Overhaul questions
Why will my Onan generator crank but not start?
Usually fuel. Gasoline left in the carburetor for a year varnishes the small passages, and the pilot circuit closes with only a trace of deposit. On a diesel unit the equivalent is a clogged filter, air in the system or a lift pump that lost prime. Both are at the low end of the band on this page, which is why we check fuel before anything expensive.
My generator starts then shuts off after a minute. What is that?
That is almost always a protection circuit shutting it down deliberately: low oil pressure, high temperature or overcrank. The fault code at the panel identifies which. If it is low oil pressure, stop starting it, because repeated cranking under that condition is how a modest repair turns into an overhaul.
Is it worth overhauling an old RV generator?
It depends on the hour meter. A unit at 4,000 hours with a burned valve is at end of service, and an overhaul spends money on the parts that have not failed yet. A unit at 900 hours with one clear fault is worth repairing. We read the meter, price both the repair and a replacement unit, and hand you both numbers.
Does the chassis engine come into this at all?
No. The house generator in the coach bay is a separate machine and it is what this page covers. Chassis engine rebuild, transmission rebuild and drivetrain work are outside what this facility performs. Drawing that line explicitly matters because the two get blurred constantly and it wastes an owner's week.
Related work
Often done at the same time
$400 to $1,500
Generator Maintenance
Interval service on a house generator: oil, filters, plugs, valve lash check and a load test to confirm output.
$2,500 to $14,000
Generator Installation
New or replacement house generator fitted with mount, fuel supply, exhaust route and transfer switch integration.
$285 to $1,500
Transfer Switch and Shore Power Repair
Inlet, cord, automatic transfer switch and surge protection repair on the 120 volt supply path.
$285 to $2,500
LP Gas System Service
Propane tank, regulator, manifold and line service with a full system pressure and leak test, performed certified.
Get a firm number on generator repair and overhaul
The band on this page is honest, and the in depth diagnostic at 1 hour at $285 turns it into a firm number. One hour minimum. Credited to an authorized repair. We are 18.4 miles from Hacienda Heights.