Atlas Copco Qc1001 Engine Engine

• Unstable voltage
  Cause: - Speed variation in engine.
  Fix: Check regularity of rotation.
• The starter motor turns the engine too slowly
  Cause: - Battery capacity too low. - Bad electrical connection. - Fault in starter motor. - Wrong grade of lubricating oil.
• The engine does not start or is difficult to start
  Cause: - Starter motor turns engine too slowly. - Fuel tank empty. - Fault in fuel control solenoid. - Restriction in a fuel pipe. - Fault in fuel lift pump. - Dirty fuel filter element. - Air in fuel system. - Fault in atomisers. - Cold start system used incorrectly. - Fault in cold start system. - Restriction in fuel tank vent. - Wrong type or grade of fuel used. - Restriction in exhaust pipe.
• Rotating bridge failure
  Cause: - Check diodes, disconnect cables.
• Regulator out of setting
  Fix: Regulate stability of regulator by acting on “STABILITY” potentiometer.
• Not enough power
  Cause: - Restriction in a fuel pipe. - Fault in fuel lift pump. - Dirty fuel filter element. - Restriction in air filter/cleaner or induction system. - Air in fuel system.
• No residual voltage
  Fix: For an instant apply on the + and – terminals of the electronic regulator a 12 V battery voltage with a 30 Ω resistor in series respecting the polarities.
• Lower than rated voltage at load
  Cause: - Voltage potentiometer out of setting.
  Fix: Reset voltage potentiometer.
• Low voltage at no load
  Cause: - Voltage potentiometer out of setting.
  Fix: Reset voltage.
• Loose sensing wires on AVR
  Fix: Check sensing wires on AVR.
• Insufficient residual voltage
  Fix: Increase the speed by 15 %.
• Higher than rated voltage at load
  Cause: - Voltage potentiometer out of setting.
  Fix: Reset voltage potentiometer.
• High voltage at no load
  Cause: - Voltage potentiometer out of setting.
  Fix: Reset voltage potentiometer.
• Failed regulator
  Fix: Substitute regulator.
• Current too high, power factor lower than 0.8; speed lower than 10 % of rated speed
  Cause: - Failed regulator.
  Fix: Substitute regulator.

Compiled from service & troubleshooting documentation across every generator set that uses the Atlas Copco Qc1001.

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.