Cummins/Onan 10CW-150R troubleshooting: 49 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan 10CW-150R — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Symptom | Cause | Remedy |
|---|---|---|
| GENERATOR OVERHEATING | Short in load circuit. Generator overloaded. Improper brush rig position. | Correct short circuit. Reduce the load, Refer to the GENERATOR section of MAINTENANCE - See Brush Rig. |
| ENGINE OVERHEATING | Improper lubrication. Poor ventilation, Dirty or oily cooling surfaces. Retarded ignition timing, Generator overloaded. | Provide ample ventilation at all times. Keep the engine clean, Retime ignition. Reduce load. |
| VOLTAGE DROPS UNDER HEAVY LOAD | Engine lacks power, Poor compression. | Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary. |
| VOLTAGE DROPS UNDER HEAVY LOAD (CONT) | Faulty carburetion, Dirty carburetor air cleaner, Choke partially closed. Carbon in cylinders or in carburetor venturi. Restricted exhaust line, Improper governor adjustment. | Check the fuel system. Clean, adjust or repair as needed. Clean and Service. Choke plate must be wide open at operating temperature. |
| ENGINE MISFIRES AT LIGHT LOAD | Carburetor idle jet clogged or improperly adjusted. Spark plug gaps too narrow. Intake air leak, Faulty ignition. | Clean or adjust. Adjust to correct gap - .025"{.018" for gas operation). Tighten manifold and carburetor mounting screws. Replace gasket if necessary. Clean, adjust, or replace breaker points, spark plugs, condenser, etc. |
| ENGINE MISFIRES AT HEAVY LOAD | Defective spark plug. Faulty ignition. Clogged carburetor. Clogged fuel screen. Defective spark plug cable. | Replace. Clean, adjust, or replace breaker points, spark plugs, condenser, etc. or retime ignition. Clean carburetor. |
| ENGINE MISFIRES AT ALL LOADS | Fouled spark plug, Defective or wrong spark plug, Leaking valves. | Clean and adjust. Replace. See VALVE SERVICE. |
| EXCESSIVE OIL CONSUMPTION, LIGHT BLUE EXHAUST | Poor compression. Usually due to worn pistons, rings, or cylinders. | Refinish cylinders. Install oversized pistons and rings. |
| BLACK, SMOKY EXHAUST, EXCESSIVE FUEL CONSUMPTION, FOULING OF SPARK PLUGS WITH BLACK SOOT, POSSIBLE LACK OF POWER UNDER HEAVY LOAD | Fuel mixture too rich. Choke not fully open. Dirty air cleaner. | See that choke opens properly. Adjust jets properly. Adjust the float level. |
| LIGHT POUNDING KNOCK | Loose connecting rod. Low oil supply, Oil badly diluted. Low oil pressure. | Replace rod bearings. Add oil. Change if necessary. Drain. Refill with proper oil. See Low Oil Pressure for remedies. |
| ENGINE STOPS UNEXPECTEDLY | Empty fuel tank, Defective ignition system. Fuel pump failure. | Refill. Check the ignition system. Repair or replace as needed. See that the STOP button lead is not grounded. |
| DULL METALLIC THUD, IF NOT BAD, MAY DISAPPEAR AFTER FEW MINUTES OPERATION, IF BAD, INCREASES WITH LOAD | Loose crankshaft bearing. | Replace, unless one of the next two remedies permanently corrects the trouble. |
| SHARP METALLIC THUD, ESPECIALLY WHEN COLD ENGINE FIRST STARTED | Low oil supply. Oil badly diluted. | Add oil. Change if necessary. Drain. Refill with proper oil. |
| PINGING SOUND WHEN ENGINE IS SUDDENLY OR HEAVILY LOADED | Remove the carbon. Reset breaker points or retime ignition. | Install correct spark plugs. Carbon in cylinders. Spark advanced too far. |
| SHARP CLICK WHEN CRANKING ENGINE | Magneto impulse coupling. | Normal condition - should stop as soon as engine starts. |
| Engine cranks too stiffly | Too heavy oil in crankcase, Engine stuck. | Drain. Refill with light oil, See PREPARATION, Disassemble and repair. |
| Engine cranks too slowly when cranked electrically | Discharged or defective battery, Loose connections, Corroded battery terminals, Brushes worn excessively or making poor contact, Short circuit in generator load circuit, Dirty or corroded points in start solenoid switch | Recharge or replace. Tighten loose connections, Clean corroded terminals, He, place cable if necessary, Replace brushes or clean commutator, Repair or replace parts necessary, Disconnect load, Replace switch. |
| Engine will not start when cranked | Faulty ignition, Lack of fuel or faulty carburetion, Cylinders flooded, Poor fuel, Foil compression, Wrong ignition timing | Clean, adjust, or replace breaker points, spark plugs, condenser etc., or retime ignition, Refill the tank. Check the fuel system. Clean, adjusi, or replace parts necessary, Ground spark plug cables, Crank engine with spark plugs moved. |
| Engine runs but voltage does not build up | Poor brush contact. | See that brushes seat well on commutator and collector rings, are free in holders, are not worn shorter than 1/2 inch, and have good spring tension. |
| Voltage is unsteady but engine is not misfiring | Speed too low, Poor commutation or brush contact, Loose connections, Fluctuating load | Adjust governor to correct speed, Refinish commutator or undercut if necessary. See that brushes seat well on commutator and collector rings, are free in holders, are not worn shorter than 1/2 inch, and have good spring tension, Tighten connections, Correct any abnormal load condition causing trouble. |
| Engine runs but voltage does not build up (cont.) | Open circuit, short circuit, or ground in generator | Refer to the GENERATOR section of MAINTENANCE |
| ENGINE RUNS GUT VOLTAGE GOES NOT BUILD UP | Poor brush contact. Open circuit, short circuit, or ground in generator. | See that brushes seat well on commutator and collector rings, are free in holders, are not worn shorter than 1/2-inch, and have good spring tension. Refer to the GENERATOR section of Maintenance. |
| VOLTAGE UNSTEADY BUT ENGINE NOT NISFIFUNG | Speed too low. Poor commutation or brush contact. Loose connections. Fluctuating load. | Adjust govemor to correct speed. Refinish commutator or undercut mica if necessary, See that brushes seat well on commutator and collector rings, are free in holders, are not worn shorter than 1/2-inch, and have good spring tension. Tighten connections. Correct any abnormal load condition causing trouble. |
| LOW OIL PRESSURE | Oil too light. OH badly diluted. Oil teo low. ODl reef valve aot seating. Badly worn bearings. Sludge on oil screen. Badly worn oi} pump. Defective oi] pressure gauge. | Drain, refill with proper oil. Drain, reGill with proper oil. Add oil. Remove and clean, or re- eplace. Replace. Remove and clean. Replace. Replace. |
| HIGH OF PRESSURE | Oil too heavy. Clogged oil passage. Dil relief valve stuck. Mefective oil pressure gauge. | Drain, refill with proper oii. Clean all lines and pas sages. Remove and cleaa. Replace. |
| EXCESSIVE DIL CONSUMPTION. LIGHT BLUE EXHAUST | Poor compression. Usually due to wom pistons, rings, or cylinders. | Refinish cylinders. Install oversize pistons and rings. |
| Choke not fully open | See that choke opens properly. Adjust jets properly. Adjust the float level. | |
| Dirty air cleaner | Clean and Service. | |
| Dull metallic thud, if not sag, may disappear after few minutes operation. 1 F Bad, increases with load | Loose crankshaft bearing. Replace, usually one of the next two remedies per manfacturerly corrects the trouble. | |
| Tapping sound | Valve clearance too great. Broken valve spring. Install new spring. | |
| Hollow clicking sound with cool engine under load | Loose piston. If noise is only slight and disappears when engine warms up, no immediate attention needed. Otherwise replace parts necessary. | |
| Voltage low at far end of line but normal near plant | Too small line wire used for load and distance. Install larger or extra wires or reduce load. | |
| Motors run too slowly and overheat at far end of line but ok hear the plant | Too small wire used for load fastall larger or extra wires of reduce load. | |
| Noisy brushes | High mica between bars of commutator. Undercut mica. Adjust to proper clearance. See VALVE TAPPETS. | |
| Excessive arcing of brushes | Rough commutator or rings. Dirty commutator or rings. Brushes not seating properly. Open circuit in armature. Brush cig out of position. Turn down. Clean. Sand to a good seat of reduce load until worn in, install a new armature. Line up properly. | |
| Spark plugs foul rapidly | Engine running “cold”. Wrong plugs. Carburetor too “rich”. Restrict air flow. Install preheater hose. Replace with correct plugs. Adjust. | |
| Oil dilution | One spark plug fouled. Leaky carburetor valve. Clean plugs. Clean. Tighten — replace if gasket is damaged. | |
| HIGH OIL PRESSURE | Oil too heavy. Clogged oil passage. Dil relief valve stuck. Mefective oil pressure gauge. | Drain, refill with proper oil. Clean all lines and pas sages. Remove and cleaa. Replace. |
| VOLTAGE UNSTEADY BUT ENGINE NOT MISFIRING | Speed too low. Poor commutation or brush contact, Loose connections. Fluctuating load. | Adjust governor to correct speed. Refinish commutator or undercut mica if necessary. See that brushes seat well on commutator and collector rings, are free in holders, are not worn shorter than 1/2 inch, and have good spring tension. Tighten connections. Correct any abnormal load condition causing trouble. |
| ENGINE BACKFIRES | Lean fuel mixture. Clogged fuel filter. Air leak at intake manifold or carburetor flange. Poor fuel. | Clean carburetor. Adjust jets. Clean. Tighten mounting screws. Replace gaskets if necessary. Refill with good, fresh fuel. See PREPARATION. Reset breaker points or retime ignition. Spark advanced too far. Intake valve leaking. Reseat or replace. |
| TOO MUCH OIL | Oil too light or diluted. Too large bearing clearance. | Drain. Refill with proper oil. Replace bearings necessary. |
| Speed too low. | Poor commutation or brush contact, Loose connections., Fluctuating load | Adjust governer to correct speed, Refinish commutator or undercut mica if necessary. See that brushes seat well on commutator and calender rings, are free in holders, are not worn shorter than 1/2 inch, and have good spring tension. Tighten connections, Correct any abnormal load condition causing trouble. |
| VOLTAGE DROPS UNDER HEAVY LOAD (CONT.) | Engine lacks power, Poor compression | See remedies under 'Engine Misfires at Heavy Load'. Tighten cylinder heads and spark plugs. If still not corrected, grind the valves. Replace piston rings if necessary. |
| ENGINE MISFIRES AT ALL LOADS (CONT.) | Broken valve spring, Defective or improperly adjusted breaker points | Replace, Adjust or replace breaker points. |
| ENGINE BACKFIRE | Lean fuel mixture, Clogged fuel filter, Air leak at intake manifold or carburetor flange, Poor fuel, spark advanced too far, Intake valve leaking | Clean carburetor. Adjust jets, Clean, Tighten mounting screws. Replace gaskets if necessary, Refill with good, fresh fuel, See PREPARATION, Reset breaker points or retime ignition, Clean, adjust, or replace breakere points, spark plugs, condenser, etc., or retime the ignition. |
| EXCESSIVE CIL CONSUMPTION, LIGHT BLUE EXHAUST | Poor compression, Usually due to worn pistons, rings, or cylinders, Oil too light or diluted, Too large bearing clearance, Engine misfires, Faulty ignition, Too much oil | Refinish cylinders. install oversize pistons and rings, Drain. Refill with proper oil, Replace bearings necessary, Refer to 'Engine Misfires At All Loads', Clean, adjust, or replace breaker points, spark plugs, condenser, etc., or retime the ignition, Drain excess oil. |
| HOLLOW CLICKING SOUND WITH COLD ENGINE | Broken valve spring, Install new spring | Install new spring |
| Engine cranks stiffly | Too heavy oil in crankcase, Engine stuck. | Drain. Refill with light oil, See PREPARATION. Disassemble and repair. |
| Engine cranks slowly when cranked electrically | Discharged or defective battery, Loose connections, Corroded battery terminals, Brushes worn excessively or making poor contact, Short circuit in generator load circuit, Dirty or corroded points in start solenoid switch | Recharge or replace. Tighten loose connections, Clean corroded terminals. He. place cable if necessary. Replace brushes or clean commutator, Repair or replace parts necessary. Disconnect load, Replace switch, |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Short in load circuit. Generator overloaded. Improper brush rig position.. See the table for the matching fixes.
Documented causes: Improper lubrication. Poor ventilation, Dirty or oily cooling surfaces. Retarded ignition timing, Generator overloaded.. See the table for the matching fixes.
Documented causes: Engine lacks power, Poor compression.. See the table for the matching fixes.