Start with the evidence, not the parts list
Good troubleshooting begins before a spanner is lifted. The technician downloads the controller fault log, asks what the set was doing when it stopped, checks what changed recently and looks at the readings from the last service. Many faults that look mechanical turn out to be wiring, sensors or settings, and the reverse is just as common.
Common faults and where to look
| Symptom | Frequent causes | First checks |
|---|---|---|
| Cranks but will not start | Air in fuel, blocked filters, fuel solenoid, low cranking speed | Fuel supply and bleeding, filter condition, battery under crank |
| Will not crank | Flat or failed battery, poor connections, starter fault, control interlock | Battery voltage, terminals, start signal at the starter |
| Shuts down on high temperature | Blocked radiator, low coolant, failed fan belt, recirculating hot air | Coolant level, radiator core, belt, airflow path |
| Shuts down on low oil pressure | Low oil, wrong grade, failed sender, worn pump | Level and grade, mechanical gauge against the sender |
| Black smoke under load | Overload, restricted air intake, injector or turbo problems | Load reading, air filter restriction, boost pressure |
| Voltage or frequency unstable | Governor or AVR settings, fuel supply, load swings | Governor response, AVR, fuel pressure, load profile |
Fuel is often the culprit
Diesel that has sat in a tank for months collects water and microbial growth, which blocks filters and damages injection equipment. On remote plants, poor storage and handling make it worse. A technician who suspects fuel will drain and inspect water separators, check filter condition and recommend testing. USP&E guidance on power plant fuel specification sets out what good fuel looks like.
Fix, prove and record
Once the cause is found and corrected, the set is run under load to prove the repair, and the fault, cause and fix are written into the asset record. Repeat faults are flagged so the next visit checks whether the remedy held. Where the answer is a major repair or an overhaul, the technician says so plainly and explains the options.
Troubleshooting FAQs
Why does my generator start on test but fail in a real outage?
A no-load test hides faults that appear under load, and the transfer switch is often not exercised. A full load test with transfer usually reveals the cause.
Should I reset a shutdown alarm and try again?
Only once, and only if it is safe. Repeated resets can turn a small fault into engine damage. Note the alarm and call a technician.
Can faults be diagnosed remotely?
Controllers with remote monitoring can show alarms and readings before the visit, which helps the technician bring the right parts, but most faults still need hands-on testing.
Get a technician on a faulty set
Tell us the alarm, the make and model, and what happened before it stopped, and we will plan the call-out.