Honda GX340 Engine

Shared across brands: Cummins/Onan, Honda

How to read your Honda engine serial & model number →

• When the engine will hot start
  Fix: 1. Is the engine switch on? 2. Does the oil alert lamp flash when the starter is pulled? 3. Is there enough fuel? 4. Are all loads disconnected from the AC receptacles? 5. Is there a spark at the spark plug? a. Remove the spark plug cap, Clean any dust from around the spark plug base, then remove the spark plug. b. Install the spark plug in the plug cap. c. Turn the engine switch on. d. Grounding the side electrode to any engine ground, pull the recoil starter to see if sparks jump across the gap. e. If any fuel has been spilled, make sure the area is dry before testing the spark plug. Fuel vapor or spilled fuel may ignite. Perform this test in a well-ventilated area. f. If there are no sparks, replace the plug. g. If the new spark plug does not spark, take the generator to an authorized Honda dealer.
• There is no electricity at the AC receptacles
  Cause: Is the breaker on?
  Fix: Turn the AC circuit breaker on. Check the electrical appliance or equipment for any defects. Take the generator to an authorized HONDA dealer if there are defects. Take the electrical appliance or equipment to an electrical shop for repair.
• The engine will not start
  Cause: Is there fuel in the NO tank. Is there enough oil in the engine? (The oil alert lamp goes on when YES cranking the engine) Is there a spark from the spark plug?
  Fix: Refill the fuel tank. Add the recommended oil. (The oil alert lamp goes on when cranking the engine) Replace the spark plug. Clean any dirt around the spark plug. Set the side electrode on the cylinder head. Crank the engine, sparks should jump across the gap. Take the generator to an authorized HONDA dealer if the engine still does not start.
• UNIT RUNS THEN SURGES
  Cause: 1. Loose or worn spark plug lead. 2. Faulty spark plug. 3. Dirty fuel filter or generator set at too steep of an angle. 4. Govenor out of adjustment.
  Fix: 1. Check spark plug lead connection. 2. Remove and clean or replace. 3. Check fuel filter and angle of generator set. 4. Contact a Honda
• UNIT RUNS THEN STOPS
  Cause: 1. Out of fuel. 2. Low oil level. 3. Excess oil.
  Fix: 1. Add fuel. 2. Add oil. 3. Reduce engine oil level.
• Turning the Start/On/Stop or On/Stop switch (depending on model) to the Off position causes the output from the ignition Control Unit to be grounded. This interupts ignition voltage and stops the engine.
  Fix: If switch does not stop engine, check to make sure switch wiring is making proper contact.
• The engine stops and will not restart.
  Fix: Check the engine oil level (see page 40) before troubleshooting in other areas.
• Running the engine with persistent spark knock or pinging can cause engine damage.
  Fix: Running the engine with persistent spark knock or pinging is misuse, and the Distributor’s Limited Warranty does not cover parts damaged by misuse.
• Occasionally you may hear a light ‘‘spark knock’’ or ‘‘pinging’’ (metallic rapping noise) while operating under heavy loads.
  Fix: This is no cause for concern. If spark knock or pinging occurs at a steady engine speed, under normal load, change brands of gasoline. If spark knock or pinging persists, see an authorized Honda generator dealer.
• Noisy Generator
  Cause: 1. Worn rotor shaft bearing 2. Rotor and stator rubbing together due to: a. varnish lumps b. rotor misaligned with crankshaft
  Fix: 1. Replace end bearing 2a. Check for varnish lumps between rotor and stator and remove as required. 2b. Follow specified assembly procedures to correct rotor to crankshaft alignment.
• No AC Output Voltage
  Cause: 1. Open AC circuit breaker. 2. Open circuit between stator main coil and AC receptacle. Defective receptacle. 3. Defective Rotor. 4. Defective stator main coil.
  Fix: 1. Locate cause of overload and correct as required. Reset breaker. 2. Check for continuity and correct if circuit is open. Check for defective receptacle/extension cords. 3. Test Rotor coil. 4. Test stator main coil.
• Generator Overheats
  Cause: 1. Generator overloaded due to defective circuit breaker. 2. Airflow restricted due to dirt or debris covering vent openings in cover or adapter. 3. Stator windings covered with oil or dirt. 4. Defective windings in rotor or stator.
  Fix: 1. Replace circuit breaker. Do not exceed specified load when operating set. 2. Clean away all dirt or debris as required. 3. Clean stator windings 4. Test each component for open, grounded, or defective.
• FAILS TO CRANK
  Cause: 1. Low battery. 2. Bad battery connection. 3. Bad start switch. 4. Bad starter motor.
  Fix: 1. Check battery electrolyte level. 2. Clean and tighten all battery and cable connections. 3. See Honda Engine Owner’s Manual.
• EXHAUSTING BLACK SMOKE
  Cause: 1. Choke is shut. 2. Dirty air filter. 3. Rich fuel mixture.
  Fix: 1. Open choke. 2. Clean or replace air filter. 3. Reduce engine oil level.
• ENGINE WON’T START
  Cause: 1. Out of fuel. 2. Fuel supply shutoff valve closed. 3. Carbon deposits on spark plug. 4. Low oil level. 5. No spark.
  Fix: 1. Add fuel. 2. Fully open fuel supply valve. 3. Remove spark plug and clean. 4. Add oil if necessary. 5. See Honda Engine Owner’s Manual.

Compiled from service & troubleshooting documentation across every generator set that uses the Honda GX340.

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

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.