San Francisco · Generator Installation & Repair
Generator Repair
Diagnosis and repair on any make, plus scheduled servicing, oil changes and load testing to stop the failure happening in the first place.
Generator Repair · San Francisco
Fixing What Failed, And Stopping The Next One
Almost every generator that fails during an outage fails for a reason that a service visit would have found. Flat or sulphated batteries, stale fuel, plugged filters, a coolant leak that emptied itself over eighteen months, a controller in a fault state nobody noticed, a fuel valve somebody closed during unrelated work. We do both halves of this: emergency generator repair when a unit will not start or will not carry load, and scheduled maintenance so that call does not happen. We work on Generac, Kohler, Cummins, Champion, Honda, Briggs and Stratton, Onan and most of the older equipment still running behind Bay Area buildings, on residential standby sets, portable units, commercial sets and industrial diesel plant. The vans carry batteries, filters, plugs, belts, controller boards and common fuel-system parts, because the majority of no-start calls are resolved on the first visit if the parts are already there. If a unit has genuinely reached the end of its life, we will say so rather than selling you a rebuild that costs more than a new set — and if it needs replacing, that is a whole house generator or commercial generator conversation, not a repair one.
Why Go With Us For Service And Repair
Generator servicing is easy to do badly and almost impossible for a customer to check. A visit can be a genuine inspection with a load test and a written report, or it can be a man in a van running the unit at no load for four minutes and marking everything green. Both produce the same invoice. Our service reports state what was measured and what was found, including the things you did not ask about, and where we recommend work we explain what happens if you leave it. We test under load rather than at idle, because a no-load run tells you the engine turns over and nothing else. We keep the maintenance history so nobody has to remember when the coolant was last changed. And we answer the phone at 2am, which is when generators actually fail, on units we installed and on units we did not.
- 24/7 emergency generator service, including on equipment installed by somebody else.
- Vans stocked with batteries, filters, belts, plugs, controller boards and common fuel-system parts.
- Testing under real load, not a four-minute no-load run that proves nothing.
- Written reports that record measurements and findings, not a page of ticked boxes.
- Generac, Kohler, Cummins, Champion, Honda, Briggs and Stratton and Onan, residential through industrial.
- Straight advice about repair versus replacement, including when the honest answer costs us the repair.
Reasons To Call For Generator Service
The symptoms that should put a service call on your list, and what they usually mean:
It will not start, or starts and stops
Overwhelmingly a battery, a fuel-delivery problem or a controller in a fault state. Batteries are the single largest cause of standby generator failure and they die quietly on a three-to-five-year cycle, so a unit that has never had one replaced is on borrowed time regardless of how new it feels.
It starts but will not take the load
The engine runs, the transfer switch does not transfer, or it transfers and immediately drops out. Usually the transfer switch itself, a voltage regulator, an alternator fault or a set that is genuinely undersized for a load that has grown since installation. This is the failure that a load test would have caught.
A red light or alarm has been on for weeks
Low coolant, low oil pressure, overcrank, low battery, exercise fault. People get used to seeing it and stop registering it, and then the unit is out of service on the night that matters. A fault light is the machine telling you it will not be there.
It has never had an oil change
Generator oil ages by time as well as by hours, and a standby unit doing twelve-minute exercise runs accumulates condensation and combustion by-products without ever getting properly hot. Annual oil and filter changes are not optional maintenance theatre; they are why the engine reaches its expected life.
It is noisier, smokier or rougher than it was
Blue smoke, black smoke, new vibration, hunting or surging, a note that has changed. On diesels this frequently means wet stacking from years of light-load running, which a load bank can clear if it is caught in time and which becomes expensive if it is not.
You just bought the building
Inheriting a generator with no history is common and the machine is often fine. What it needs is one full inspection and a load test so somebody knows what condition it is actually in, rather than an assumption that it works because it is there.
Tell us the make, the rough age and what it is doing, and we will tell you on the phone whether it sounds like a callout or something to book into a service visit. Call: (415) 818-1837
How A Service Or Repair Call Works
Diagnose first, quote second, and never a surprise on the invoice.
1. Phone triage
Make, model, rough age, what it is doing and what the controller says. A good share of no-start calls are resolved or at least correctly parted before anybody drives out, which saves you a visit and gets the right part on the van.
2. On-site diagnosis
Battery and charging system, fuel supply and quality, filters, oil and coolant, controller fault history, transfer switch operation, and a start attempt with instrumentation on it. We find the actual cause rather than replacing parts in hope.
3. Quote before the work
You get the diagnosis, the fix, the price and the alternative, including whether the machine is worth the repair. On emergency calls we will get you running first where that is safely possible, then quote the permanent fix properly.
4. Repair, test under load, report
The work, then a start-transfer-load test to prove it, then a written report of what was found and what was done. If the unit belongs on a maintenance schedule after that, we set it up so nobody has to remember it next year.
Annual Servicing, Oil Changes, Load Tests And Emergencies
What generator maintenance actually consists of, and what each part is for:
Annual generator maintenance
Once a year for a residential standby unit: oil and filter, air filter, spark plugs on gas sets, belts and hoses, battery test and terminals, coolant condition on liquid-cooled machines, valve clearance on schedule, enclosure and mounting hardware, controller fault history, and a run under load. Commercial and industrial sets move to twice a year, with an annual major service on top.
Generator oil change intervals
For most air-cooled residential standby units, annually or every 100 to 200 running hours, whichever comes first — and for almost every house it is the calendar, not the hours. Diesel sets on commercial duty follow hours more closely. The reason time matters is that short exercise runs never fully warm the oil, so moisture and combustion by-products accumulate even though the hour meter has barely moved.
Batteries, the most common failure of all
Standby generator batteries last three to five years, and they fail in a way that gives no warning during a twelve-minute exercise cycle but shows up instantly under a real cold start. Every service visit should include a proper load test on the battery, not a voltage reading, and replacing one preemptively at four years is cheap insurance.
Fuel: stale gasoline, aged diesel and gas supply
Gasoline in a portable goes off in three to six months. Diesel in a tank degrades over years, picks up water and grows microbial contamination, which plugs filters at exactly the wrong moment — hence fuel testing and polishing on commercial sites. Natural gas sets do not have a fuel problem, but they do have a supply pressure problem if somebody has added appliances since the generator went in.
Load testing and load banking
A no-load exercise run proves the engine starts. A load test proves the machine holds output, the alternator regulates and the transfer switch works, and on diesels a resistive load bank at rated capacity also burns off the carbon that light running deposits. Any set on a critical load should get one annually, and a set nobody has ever tested should get one now.
Diesel generator repair
Injectors, lift and injection pumps, glow systems, turbochargers, cooling systems, wet stacking, coolant and lubricant analysis, and the fuel system generally. Diesel plant is repairable well past the point where a small gas unit would be scrap, so an old industrial set is frequently worth fixing when a fifteen-year-old air-cooled residential unit is not.
Emergency generator repair, 24/7
Generators fail at 2am in a storm, which is a design feature of the universe. We run genuine round-the-clock callout, and for restaurants, clinics and facilities on a service plan we prioritize by consequence rather than by call order. Where a repair cannot be completed the same night, we bring in a rental generator so the site keeps operating.
Transfer switch faults
A good share of what people report as generator failure is actually the automatic transfer switch: contacts, controls, sensing or exercise timers. It is a separate device with its own failure modes, it is frequently the older component in the system, and it deserves testing on its own rather than being assumed good because the engine ran.
What Generator Repair And Servicing Costs
Service is priced per visit and repairs are quoted after diagnosis, never before. What moves the number:
- Residential or commercial. An air-cooled home standby service is a straightforward annual visit; a commercial or industrial set is a longer job with more to inspect and more to document.
- Whether it is an annual service or an emergency callout. Scheduled work during business hours is the cheap case; 2am on a holiday weekend is not, and we say so up front.
- What the diagnosis finds. A battery and a set of filters is a small invoice. An alternator, a controller board or an injection pump is not.
- Load-bank testing, which is priced separately because it needs equipment brought to site and a defined test period.
- Fuel work on diesel sites — testing, polishing, filter and tank work — which is its own line rather than part of a routine service.
- Parts availability. Current Generac, Kohler, Cummins and Champion parts are usually on the van or next day; obsolete parts for a twenty-five-year-old set can take longer and cost more.
Service plans are billed annually and include the visit, the consumables and priority response, which is what most customers want once they have had one bad night. Where a repair is not worth doing, we will price the alternative honestly — usually a new standby install or, for a business, a commercial unit — and you can see everything we cover on generator service across San Francisco.
Frequently Asked Questions
How often should a generator be serviced?
A residential standby unit wants a full service once a year and a short exercise run weekly, which the controller does by itself. Commercial sets want a minor service twice a year and a major service annually. Anything on a life-safety or high-value load should also get a load-bank test each year. Sets that run real hours follow an hours-based interval instead of the calendar.
How often does a generator need an oil change?
Annually, or every 100 to 200 running hours, whichever comes first — and for nearly every home standby unit it is the year that comes first. Short exercise cycles never get the oil properly hot, so moisture and combustion by-products build up even with almost no hours on the meter. Diesel sets running real load follow their hour intervals closely.
How long will a generator run continuously?
A natural gas standby unit runs indefinitely while the gas main is live, which is why it is the default in this city. A diesel set runs as long as its tank holds out, typically twenty-four to forty-eight hours on a sub-base tank before it needs refuelling. A propane unit depends entirely on tank size. A gasoline portable is eight to twelve hours a tank and needs refuelling by hand, in the dark, in the rain.
Why will my generator not start?
In order of likelihood: the battery, the fuel, or a controller sitting in a fault state. Batteries last three to five years and fail without warning under a real cold start. Fuel means stale gasoline, degraded diesel, plugged filters or a gas valve closed during unrelated work. Beyond that it is starters, solenoids, control boards and wiring. We diagnose before quoting rather than replacing parts hopefully.
Do you repair generators you did not install?
Yes, and it is a large share of what we do. We work on Generac, Kohler, Cummins, Champion, Honda, Briggs and Stratton and Onan equipment, residential through industrial, whoever installed it. On a machine we have not seen before the first visit includes a full inspection and a load test so nobody is guessing about its condition.
Is it worth repairing an old generator?
Depends on the class of machine. Industrial diesel plant is designed to be rebuilt and is frequently worth repairing at twenty-five years. A fifteen-year-old air-cooled residential set needing an alternator or a control board usually is not, because the repair approaches the cost of a new unit with a new warranty. We will tell you which one you have, including when that answer loses us the work.
Need a generator in San Francisco?
Tell us the address and what has to stay running, and we will come back the same day with a free estimate and one fixed price.
Or call us now: (415) 818-1837