Electrical and Power
Generator Repair and Service
In short: Most generator failures are fuel system failures caused by sitting unused, which is why the single most effective thing an owner can do is run it under load for half an hour every month.
- Typical range
- $400 to $12,000+
- Labor hours
- 2 to 50 hours
- Updated
Generators fail from disuse far more often than from use. That single fact explains most of what comes through the shop, and it also means most of it was preventable by a habit that costs nothing.
What sitting does
Gasoline units. Modern fuel degrades in weeks. What is left behind is varnish, and it settles in the carburettor bowl and blocks the jets, which are small enough that a trace is enough. A generator that ran perfectly in September will not start in March, and the reason is in the carburettor.
Diesel units. Different failure. Water accumulates from condensation, microbial growth follows, and the result blocks filters and corrodes injection components. Diesel also gels in genuine cold, though that matters less here than in most of the country.
Both. Seals dry and shrink. Moisture condenses inside the housing and sits on windings. Rodents nest in warm enclosures and chew wiring and insulation. Batteries used for starting sulphate and lose capacity.
The prevention is thirty minutes a month under real load. Not a brief idle with nothing connected, which warms the unit without getting it to operating temperature and lets moisture condense rather than burning it off. Load it to half rated output or more, let it get properly hot, and let it stay there.
What we work on
Onan and Cummins across the range, gasoline, diesel and LP, in motorhomes, fifth wheels, commercial trucks, mobile business vehicles, municipal fleet equipment and emergency vehicles.
Services cover scheduled service, fuel system cleaning and carburettor rebuild, injection service on diesel units, control board and voltage regulator diagnosis and replacement, starting system and battery work, exhaust repair, cooling system service, mounting and vibration isolation repair, full overhaul, and new installation.
Diagnosis before parts
Generator symptoms overlap heavily, which is why swapping components is expensive here.
A unit that will not start could be fuel, ignition, compression, the starting circuit or a control board locking it out. A unit that starts and shuts down under load could be fuel delivery, cooling, a regulator or a winding fault. A unit producing incorrect voltage could be a regulator, a winding or a speed problem.
So we test rather than guess: compression, fuel pressure and delivery, ignition, output voltage and frequency under stepped load, control board fault codes where the unit has them, and thermal behaviour through a loaded run. Diagnostics are $285 for the first hour, credited back against an authorized repair.
What it costs
| Job | Typical range | Hours |
|---|---|---|
| Diagnosis | $285 first hour | 1 to 3 |
| Scheduled service | $400 to $900 | 2 to 4 |
| Carburettor rebuild or fuel system clean | $700 to $1,800 | 3 to 8 |
| Control board or regulator replacement | $900 to $2,500 | 4 to 10 |
| Starting and charging system repair | $600 to $1,800 | 3 to 8 |
| Exhaust repair | $500 to $1,500 | 2 to 7 |
| Full overhaul | $3,500 to $8,500 | 16 to 40 |
| New installation | $6,000 to $12,000 | 25 to 50 |
Mechanical labor is $260 per hour. See the pricing page.
Repair or replace
The honest calculation involves hours, compression and what has failed.
A unit with moderate hours and one specific failure is usually worth repairing. A unit at high hours with low compression across cylinders, a burnt winding, a cracked housing or a scored crankshaft usually is not, because the next failure is close behind and you will have paid twice.
We give you the numbers rather than a recommendation dressed as a diagnosis. Hours, compression figures, what has failed, what is likely next, and the cost of each path.
Exhaust and carbon monoxide
Worth stating separately because it is the one generator fault that is genuinely dangerous.
Generator exhaust systems corrode, crack and separate at joints, and a leak under the coach can put carbon monoxide into the living space through a floor penetration or an open window. It is not detectable by smell.
Every generator job here includes an exhaust inspection, and we will not return a vehicle with a compromised generator exhaust. If you have a carbon monoxide detector that has ever alarmed, or if occupants have had headaches while the generator ran, treat it as urgent rather than as a nuisance.
Solar alongside
Owners increasingly pair a generator with solar and lithium. That combination works well: solar covers baseline load silently, the generator covers air conditioning and recovery. The generator ends up running a fraction as often, which suits the machine, because a generator that runs occasionally under real load is in a far better place than one that never runs at all.
Estimates are $150 and credited back against an authorized repair.