Generator Repair & Troubleshooting

Diagnosis and repair guidance for diesel generating sets — starting faults, protective shutdowns, output problems, cooling, fuel and control systems. Written for technicians working on real plant, with the safety constraints stated rather than assumed.

What this covers

• ▪Starting and cranking faults — Generator Cranks But Will Not Start, Starter Motor Clicks But Will Not Crank, Generator Starting Battery Not Charging
• ▪Protective shutdowns — oil pressure, coolant temperature, overspeed — Generator Low Oil Pressure Shutdown, Generator Overheating and High Coolant Temperature Shutdown
• ▪Output faults — no voltage, unstable voltage, frequency problems — Generator Runs But Produces No Voltage, Generator Voltage Unstable or Hunting, AVR Fault Diagnosis
• ▪Fuel system diagnosis — Generator Starts Then Stops, Diesel Fuel Contamination, Generator Excessive Smoke
• ▪Cooling system diagnosis — Generator Overheating and High Coolant Temperature Shutdown
• ▪Controller and communication faults — Reading a Generator Controller Alarm Correctly, Generator Starts in Manual But Not in Auto, Reading J1939 Engine Fault Codes
• ▪Transfer switching and load acceptance — ATS Not Changing Over, Generator Will Not Transfer Back to Mains

Diagnosis guides

• Generator Cranks But Will Not Start — Diagnosis and Repair

  Cummins, Perkins, Caterpillar, Volvo Penta, Deutz, Doosan, FG Wilson, SDMO and other electronic or mechanically governed diesel sets

  10 diagnostic steps · intermediate · technician

• Generator Starts Then Stops — Diagnosis and Repair

  Cummins, Perkins, Caterpillar, Volvo Penta, Deutz, Doosan, FG Wilson, SDMO and other electronically or mechanically governed diesel sets

  10 diagnostic steps · intermediate · technician

• Generator Low Oil Pressure Shutdown — Diagnosis and Repair

  All diesel generating sets with oil pressure protection — Cummins, Perkins, Caterpillar, Volvo Penta, Deutz, Doosan, FG Wilson, SDMO and others

  9 diagnostic steps · intermediate · technician

• Generator Runs But Produces No Voltage — Diagnosis and Repair

  Brushless and brushed synchronous alternators fitted to Cummins, Perkins, Caterpillar, FG Wilson, SDMO and other sets. Stamford, Leroy-Somer, Marathon, Mecc Alte and equivalent generator ends.

  10 diagnostic steps · advanced · qualified electrician

• Generator Voltage Unstable or Hunting — Diagnosis and Repair

  Brushless and brushed synchronous alternators with electronic AVRs, on mechanically or electronically governed diesel sets

  10 diagnostic steps · advanced · qualified electrician

• Generator Overheating and High Coolant Temperature Shutdown

  Open and canopied diesel generating sets, single- and three-phase, standby and prime

  8 diagnostic steps · intermediate · technician

• AVR Fault Diagnosis — Before You Replace the Regulator

  Brushless self-excited and PMG-excited alternators on diesel generating sets, single- and three-phase

  8 diagnostic steps · advanced · qualified electrician

• Starter Motor Clicks But Will Not Crank — Diagnosis and Repair

  Diesel generating sets with electric starting, single- and three-phase, standby and prime

  8 diagnostic steps · intermediate · technician

• Generator Starting Battery Not Charging — Diagnosis and Repair

  Diesel generating sets with electric starting, standby and prime, with engine-driven charging alternator and separate mains battery charger

  8 diagnostic steps · intermediate · technician

Related guides

Filed under another category, but they cover part of the scope above.

• Diesel Fuel Contamination — Water, Dirt and Microbial Growth

  in Fuel & Combustion Diagnosis · 8 diagnostic steps

• Generator Excessive Smoke — Reading Black, Blue and White

  in Fuel & Combustion Diagnosis · 9 diagnostic steps

• Reading a Generator Controller Alarm Correctly — Why a Fault Code Is Not a Diagnosis

  in Controller Diagnostics · 8 diagnostic steps

• Generator Starts in Manual But Not in Auto

  in Controller Diagnostics · 8 diagnostic steps

• Reading J1939 Engine Fault Codes — What SPN and FMI Actually Tell You

  in Fault Codes & Diagnostic Messages · 8 diagnostic steps

• ATS Not Changing Over — Automatic Transfer Switch Diagnosis

  in ATS & Changeover Panel Diagnosis · 8 diagnostic steps

• Generator Will Not Transfer Back to Mains

  in ATS & Changeover Panel Diagnosis · 7 diagnostic steps

Related categories

• Controller Diagnostics
• Fuel & Combustion Diagnosis
• Engine Mechanical Diagnosis
• ATS & Changeover Panel Diagnosis