Generator brands · Complete sets
Repairing, Servicing and Maintaining FG Wilson Generator Sets
Our technicians repair, service and maintain FG Wilson generators where they stand, anywhere in Gauteng, from small canopied standby sets to large sets for factories, hospitals and office parks. Most FG Wilson diesel sets run on a Perkins engine with a PowerWizard or earlier controller, so a repair usually involves the engine, controller, alternator and base tank together. Because most are standby sets, the typical fault shows up when a set that has stood idle is suddenly asked to carry the building.
Established 2006
20 years of experience
24/7 operations
We Arrive Within 1–2 Hours
(usually within 1 hour)
Free callouts and quotations
One-year warranty
Qualified and certified technicians
We Service & Repair All Generator Brands
All generator makes and models
1 kVA–20,000 kVA capability
Reading an FG Wilson nameplate
| Where to look | What it tells us |
|---|---|
| Model code | What it tells usA code starting with P marks a Perkins-powered set, and the number after it relates to the kVA rating |
| Standby and prime ratings | What it tells usHow hard the set may be worked. Standby is the higher figure, for limited hours during outages |
| Set serial number | What it tells usThe build: controller, alternator, canopy and options, which can differ between sets with the same model code |
| Perkins engine number | What it tells usThe engine series and build, which decide the filters, belts, gaskets and service schedule |
| Alternator plate | What it tells usThe alternator frame and the voltage regulator fitted, needed for any voltage fault |
Perkins engines and Leroy-Somer alternators
The engine grows with the set. The smallest FG Wilson sets, up to about 30 kVA, use three- and four-cylinder Perkins 400-series engines, and the 1100 series covers most sets from there to around 200 kVA. Larger commercial and industrial sets step up to bigger six-cylinder engines such as the 2000 series, and the large 4000-series engines power the biggest sets, from roughly 800 kVA upwards. Each series has its own filters, cooling layout and fuel system; see our Perkins engine page.
On the electrical side, many FG Wilson sets carry Leroy-Somer alternators with a regulator matched to the frame size; others use different makes. A voltage fault is traced through the regulator, exciter, rotating diodes and windings, as described under AVR repairs. PowerWizard controllers on newer sets keep an event log and show alarms as text. Older sets may have an earlier electronic panel or a simple panel of lamps, meters and relays, where faults are found by testing rather than reading a screen.
What we work on in an FG Wilson set
A canopied FG Wilson set packs the engine, alternator, controller, radiator and base fuel tank into one enclosure, and a fault in one often shows up in another. The photo shows that general layout on a canopied diesel set of another make, with the alternator in one bay and the engine in the other.
- Perkins engine: fuel, lubrication, cooling and governing
- PowerWizard or earlier panel, mains sensing and auto start
- Alternator: regulator, diodes, bearings and insulation
- Canopy seals, louvres, base tank and starting battery
Why standby sets fail when they are needed
An FG Wilson standby set spends most of its life waiting. It rarely reaches a service interval by hours, so it is serviced by time: oil and coolant age, hoses harden and diesel in the base tank collects water from condensation. The most common weak point is the starting battery, left flat or tired by a charger fault nobody noticed.
Load shedding turned many of these sets into regular workers, starting several times a week on a building load. That brings the hour-based intervals round faster and exposes weak batteries, perished hoses and blocked fuel filters. A maintenance plan with test runs between services catches them before an outage does. For water in the base tank, see diesel fuel contamination.
Situations we meet on FG Wilson standby sets
| Symptom | Likely causes | Repair route |
|---|---|---|
| Did not start when the mains failed | Likely causesFlat battery or charger fault, controller not in auto, mains-sensing fault | Repair routeGenerator not starting |
| Running, but the building has no power | Likely causesChangeover not transferring, output breaker tripped, AVR or excitation fault | Repair routeRunning but no power |
| Stays on the generator after the mains returns | Likely causesMains-sensing fuse or relay, changeover contactor or timer fault | Repair routeChangeover and ATS problems |
| Battery flat after standing | Likely causesCharger fault or blown charger fuse, an ageing battery, a parasitic drain | Repair routeBattery not charging |
| Speed hunting or unstable frequency | Likely causesGovernor or actuator, restricted fuel supply, air in the fuel | Repair routeFrequency and speed problems |
| Water found in the fuel | Likely causesCondensation or rainwater in the base tank, poor-quality fuel | Repair routeFuel system repairs |
| Chewed wiring or nests in the canopy | Likely causesRodents and birds in sets that stand unused for long periods | Repair routeGenerator repairs |
Older FG Wilson sets: repair, retrofit or replace
Obsolete control panels: Control panel repairs
Early panels with lamps, meters and relays can often be repaired. If not, a modern controller is wired in and set up for the engine and alternator.
Tired alternators: Generator rewinding
Bearings are replaced and windings tested for insulation. Failed windings can be rewound instead of scrapping the alternator.
Rusted canopies and base tanks: Leaks
Corroded floors, failed door seals and weeping base tanks are repaired where the steel allows, before water reaches the electrics or the fuel.
Independent service
We Service & Repair All Generator Brands
Onsite Generator Repairs is an independent generator specialist. We repair, service and maintain FG Wilson equipment as part of our work on every make of generator.
Manufacturer warranty claims go through the manufacturer’s own network. If your generator is still under warranty, check the warranty terms before arranging work by anyone else.
Brand names and trademarks belong to their respective owners. Onsite Generator Repairs is an independent service and repair company.
Service areas
Where we work in Gauteng
FAQ
Frequently asked questions
Is an FG Wilson generator a Caterpillar?
FG Wilson is owned by Caterpillar but is a separate brand of sets. Most FG Wilson sets use Perkins engines, which Caterpillar also owns. See our Caterpillar page for Cat-built sets.
My FG Wilson set is old. Is it worth repairing?
Often, yes. The engine and alternator in older sets can usually be repaired, and an obsolete controller can be replaced with a modern one. See repair or replace.
Why is there water in my FG Wilson base tank?
Condensation forms as the tank warms and cools, and rain can enter through a poorly sealed filler or vent. Water settles at the bottom, where the fuel pickup can draw it in. Draining it is part of servicing.
Which oil and filters does my FG Wilson set take?
Those for the Perkins engine fitted, identified from its engine number rather than the set model, since sets with the same model code can carry different engine builds. We fit genuine Perkins parts or quality equivalents made to the same specification, and the quote says which.
Related pages
Related services
Related generator problems
Generator types
Related brands
Who we work for
Need a generator technician?
- 24/7 operations
- We Arrive Within 1–2 Hours (usually within 1 hour)
- Free callouts and quotations