Hercules G3400 Engine

• Starter not engaging
  Fix: Drive pinion may be spinning. Automotive crank plants only
• S1 to terminal t3 on regulator open.
  Fix: *Correct connections.
• No outflow (no exciter voltage-into AC volts)
  Cause: Regulator relay RR could be causing overcharged or undercharged battery--check this after resistor check
  Fix: Check contacts of relay CC may not be closing to complete battery charging circuit. Check brushes, AC leads, and AC armature for open circuits
• No build-up.
  Cause: L Open circuit between battery and field. l Battery discharged.
  Fix: *Make correct connections. *l Charge battery.
• Load relay L dirty or open contacts
  Fix: Check for dirty or open contacts--replace relay if needed
• Insufficient load
  Fix: A load of 60 watts or more is needed to start automatic plant. A remote switch can be added to test run these plants--check diagrams
• Generator output erratic.
  Cause: L Regulator sensing terminals not connected properly.
  Fix: *Check terminals 5 and 6 (120 V. connection) or terminals 5 and 7 (240 V. connection). *l Correct connections.
• Generator faulty on plants with automotive cranking
  Fix: Check for faulty DC generator--excessive resistance in R2 resistor. If overcharging occurs, R2 resistance may be too little
• Dirty commutator.
  Fix: *Clean commutator.
• Cranking reset trips during cranking
  Fix: Reset the reset button--if plant still does not crank, check for open circuit
• Cranking contactor C contacts do not close when switch is moved to on position
  Fix: Replace relay C
• Choke heater circuit failure
  Cause: The choke valve could ‘stick’ the air cleaner
  Fix: Check the Ohm value of the resistor with a Volt-Ohmmeter. If faulty and allows higher voltage, it could cause the choke for starting
• Check field circuit for open shunt
  Cause: Open field resistor connection
• Center tap missing on three wire automatic plants
  Fix: Check for loose leads or missing center tap
• Battery not being charged properly
  Cause: Check condition of battery--may be sulfated or have cracked cell. Replace as needed
  Fix: Check charge switch if left in HAND CRANK position, battery will not be charged

Compiled from service & troubleshooting documentation across every generator set that uses the Hercules G3400.

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

• Chicago Pneumatic 250RG-2 — Compressor
• Quincy Compressor QS250 — Compressor

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.