Northern Lights M20C troubleshooting: 96 symptom-cause-remedy entries from the manufacturer's own service documentation.
Northern Lights M20C — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Battery will not charge | Loose or corroded connections | Clean and tighten battery connections |
| Battery will not charge | Sulfated or worn out batteries | Check specific gravity of each battery; Check electrolyte level of each battery |
| Battery will not charge | Loose or defective alternator belt | Adjust belt tension; Replace belt |
| Starter inoperative | Check DC circuit breaker | If the breaker is tripped, reset it |
| Starter inoperative | Loose or corroded connections | Clean and tighten loose battery and harness plug connection |
| Starter inoperative | Low battery output | Check specific gravity of each battery; Check electrolyte level of each battery |
| Starter inoperative | Defective electrical system ground wire | Repair or replace |
| Starter cranks slowly | Low battery output: Batteries too small; Battery cables too small | Check specific gravity of each battery; Replace battery if necessary |
| Starter cranks slowly | Low battery output: Check electrolyte level of each battery | If low, fill cells with distilled water |
| Starter cranks slowly | Crankcase oil too heavy | Fill with oil of appropriate viscosity |
| Starter cranks slowly | Loose or corroded connections | Clean and tighten loose connections |
| Entire electrical system does not function | Check DC circuit breaker | If breaker is tripped, reset it |
| Entire electrical system does not function | Faulty connection | Clean and tighten battery and harness plug connections |
| Entire electrical system does not function | Sulfated or worn out batteries | Check specific gravity and electrolyte level of each battery |
| Engine hard to start or will not start | Improper starting procedure | See starting section of this manual. Take special note of Bypass Switch operation |
| Engine hard to start or will not start | No fuel | Check level of fuel in fuel tank |
| Engine hard to start or will not start | Low battery output | Check electrolyte level and condition |
| Engine hard to start or will not start | Excessive resistance in starting circuit | Clean and tighten all battery connections |
| Engine hard to start or will not start | Crankcase oil too heavy | Use oil of proper viscosity |
| Engine hard to start or will not start | Improper type of fuel | Consult fuel supplier and use proper type of fuel for operating condition |
| Engine hard to start or will not start | Water, dirt or air in fuel system | Drain, flush, fill and bleed system |
| Engine hard to start or will not start | Clogged primary fuel filter element | Clean or replace filter element |
| Engine hard to start or will not start | Clogged secondary fuel filter element | Replace filter element |
| Engine hard to start or will not start | Dirty or faulty injection nozzles | Have your dealer check injection nozzles |
| Engine runs irregularly or stalls frequently | Below normal engine temperature | Remove and check thermostat |
| Engine runs irregularly or stalls frequently | Clogged primary fuel filter element | Clean or replace filter element |
| Engine runs irregularly or stalls frequently | Clogged secondary fuel filter element | Replace secondary filter element |
| Engine runs irregularly or stalls frequently | Water or dirt in the fuel system | Drain, flush, fill and bleed system |
| Engine runs irregularly or stalls frequently | Dirty or faulty injection nozzles | Have your dealer check injection nozzles |
| Engine runs irregularly or stalls frequently | Air in fuel system | Inspect clamps and hoses on suction side of fuel pump for air leak |
| Engine runs irregularly or stalls frequently | Improper type of fuel | Consult fuel supplier and use proper type of fuel for operating condition |
| Lack of engine power | Engine overloaded | Reduce load |
| Lack of engine power | Intake air restriction | Service air cleaner |
| Lack of engine power | Clogged primary fuel filter element | Clean or replace filter element |
| Lack of engine power | Clogged secondary fuel filter element | Replace filter element |
| Lack of engine power | Improper type of fuel | Consult fuel supplier and use proper type of fuel for operating conditions |
| Lack of engine power | Overheated engine | See "Engine Overheats" in next category |
| Lack of engine power | Below normal engine temperature | Remove and check thermostat |
| Lack of engine power | Improper valve clearance | Reset valves. Best done by dealer |
| Lack of engine power | Dirty or faulty injection nozzles | Replace injectors. Best done by dealer |
| Starter Cranks Slowly | Low battery output | Battery is too small; Battery cables are too small. |
| Starter Cranks Slowly | Check specific gravity of each battery | Replace battery if necessary. |
| Starter Cranks Slowly | Check electrolyte level of each battery | If low, fill cells with distilled water. |
| Engine Hard to Start or Will Not Start | Lift pump malfunction | Repair lift pump. |
| Engine Runs Irregularly or Stalls Frequently | Control lever adjusted incorrectly | Adjust control lever. |
| Engine Runs Irregularly or Stalls Frequently | Uneven compression pressure between cylinders | Check cylinder compression pressure. |
| Lack of Engine Power | Injection pump not getting fuel | Have injection pump checked. |
| Lack of Engine Power | Poor cylinder compression pressure | Check bore for wear, or check alignment of nozzle holder. Re-adjust valve clearance. |
| Engine Overheats | Low coolant level | Fill tank or radiator to proper level, with proper mixture of coolant; Check hoses for loose connections and leaks. |
| Engine Overheats | Air cleaner element clogged | Clean or replace. |
| Engine Overheats | Keel cooling tubes have been painted | Remove paint from tubes. |
| Engine Overheats | Cooling system interior dirty | Flush cooling system. |
| Engine Overheats | Defective thermostat | Remove and check thermostat. |
| Engine Overheats | Defective temperature gauge | Check water temperature with thermometer and replace gauge if necessary. |
| Engine Overheats | Water pump impeller worn/broken | Check impeller and replace if necessary. |
| Engine Overheats | V belts slipping | Fix belts to proper tension. |
| Engine Knocks | Insufficient oil | Call your dealer. |
| Engine Knocks | Injection pump out of time | Call your dealer. |
| Engine Knocks | Below normal engine temperature | Check your thermostats; Check water temperature to see if temperature gauge is working properly. |
| Engine Knocks | Engine overheating | See "Engine Overheating" section. |
| High Fuel Consumption | Improper type of fuel | Use correct fuel for temperature. |
| High Fuel Consumption | Clogged or dirty air cleaner | Service air cleaner. |
| High Fuel Consumption | Improper valve clearance | See your dealer. |
| High Fuel Consumption | Injection nozzles dirty | See your dealer. |
| High Fuel Consumption | Injection pump out of time | See your dealer. |
| High Fuel Consumption | Engine not at proper temperature | Check your thermostats; Check water temperature with thermometer and replace gauge if necessary. |
| High Fuel Consumption | Fuel leakage | Improper installation or tightening. |
| High Fuel Consumption | Excessive load on engine | Check loads. |
| Below Normal Engine Temperature | Thermostat not working properly | Check thermostat. |
| Below Normal Engine Temperature | Temperature gauge not working properly | Check water temperature with thermometer. |
| Engine Malfunctions at High Output Range | Fuel supply insufficient | Air in fuel system or clogged fuel filter element. |
| Engine Malfunctions at High Output Range | Fuel injection amount between plungers uneven | Check fuel injectors. |
| Engine Malfunctions at High Output Range | Valve clearance adjusted incorrectly | Re-adjust valve clearances. |
| Engine Malfunctions at High Output Range | Valve spring broken | Replace valve spring. |
| Engine Malfunctions at High Output Range | Governor spring broken | Replace governor spring. |
| Low Oil Pressure | Low oil level | Fill crankcase to proper level. |
| Low Oil Pressure | Improper type of oil | Drain and fill crankcase with correct oil. |
| Low Oil Pressure | Partially plugged oil filter | Replace filter. Check bearings, oil pump, and relief valve for wear. |
| High Oil Consumption | Break-in period | Oil consumption decreases after break in. |
| High Oil Consumption | Crankcase oil too light | Use proper viscosity oil. |
| High Oil Consumption | Oil leaks | Check for leaks in lines around gaskets and drain plug. |
| Engine Emits Black or Gray Exhaust Smoke | Clogged or dirty air cleaner | Service air cleaner. |
| Engine Emits Black or Gray Exhaust Smoke | Defective muffler (back pressure too high) | Have dealer check back pressure. |
| Engine Emits Black or Gray Exhaust Smoke | Improper fuel | Use correct fuel for temperature. |
| Engine Emits Black or Gray Exhaust Smoke | Injection nozzles dirty | See your dealer. |
| Engine Emits Black or Gray Exhaust Smoke | Engine timing off | See your dealer. |
| Engine Emits White Smoke | Improper fuel | Use correct fuel for temperature. |
| Engine Emits White Smoke | Cold engine | Warm up engine to normal operating temperature. |
| Engine Emits White Smoke | Defective thermostat | Remove and check thermostat. |
| Starter Cranks Slowly | Battery is too small | |
| Starter Cranks Slowly | Battery cables are too small | |
| Starter Cranks Slowly | Low electrolyte level | Check electrolyte level of each battery; if low, fill cells with distilled water |
| Entire Electrical System Does Not Function | DC circuit breaker tripped | Check DC circuit breaker; if breaker is tripped, reset it |
| Engine Overheats | Keel cooling tubes have been painted (marine) | Remove paint from tubes |
| Engine Overheats | Cooling system needs flushing | Flush cooling system |
| Engine Emits White Smoke | Engine timing off | See your dealer |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Improper starting procedure; No fuel; Low battery output; Excessive resistance in starting circuit. See the table for the matching fixes.
Documented causes: Low coolant level; Air cleaner element clogged; Keel cooling tubes have been painted; Cooling system interior dirty. See the table for the matching fixes.
Documented causes: Engine overloaded; Intake air restriction; Clogged primary fuel filter element; Clogged secondary fuel filter element. See the table for the matching fixes.