Mercury 20 2-stroke Troubleshooting
| Engine Model: Mercury 20 Hp |
| Engine Type: 2-stroke 2-cylinder gasoline outboard engine |
| Total Displacement: 24.4 cu.in (400 cc) |
| Rated Engine Power: 20 Hp (14.9 kW) at 5500 rpm |
| Fuel System: Float type carburetor |
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| Engine starts up hard or doesn't start |
Fuel tank is empty - Fill it up.
Improper fuel grade - Change fuel.
Air trapped in fuel system - Bleed air.
Defective spark plug wire connection - Inspect the spark plug wire connection, replace or repair.
Spark plug is faulty - Change spark plug as required.
Plugged fuel filter - Fuel filter needs to be replaced.
Carburetor components worn out - Repair or replace parts.
Dirt in the fuel lines - Service fuel lines.
Fuel tank air vent closed or restricted - Open or service air vent.
Lack of fuel pump pressure - Repair or change fuel pump.
Reed valve is defective or worn - Install new reed valve.
| Engine starts but immediately stops |
Faulty spark plug - Install new spark plug.
Faulty or dirty carburetor - Replace or service carburetor.
Ignition coil is faulty - Install a new ignition coil.
Fuel tank air vent closed or restricted - Open or service air vent.
Fuel pump pressure is low - Change or rebuild fuel pump.
| Engine runs intermittently |
Ignition system failure - Check ignition and replace faulty components.
Dirty or faulty fuel pump - Service or replace fuel pump.
Wrong carburetor adjustment - Adjusting carburetor correctly.
Fuel lines are dirty - Fuel lines need to be cleaned.
Fuel tank air vent clogged or closed - Open or service air vent.
Fuel filter is dirty - Install new filter.
Gaskets are worn - Replace gaskets.
Excessive engine load - Load reducing required.
Too lean carburetor mixture - Set the carburetor properly.
Incorrect ignition timing - Set the ignition timing properly.
Damaged thermostat - Thermostat need to be replaced.
Faulty water pump - Water pump need to be replaced.
Incorrect propeller selection - Install correct propeller.
Damaged or bent propeller - Replace propeller.
Outboard engine is positioned too low or too high - Position the engine correctly.
Stale fuel - Change fuel.
Engine overloaded - Load reducing is recommended.
Low idle speed setting is not correct - Adjust the low idle speed.
Fuel pump is clogged or faulty - Test fuel pump and change if necessary.
Crankshaft or main bearings are worn out - Need to install new components.
Worn piston rings or cylinder bore - Change defective components.
Carburetor is improperly adjusted or dirty - Carburetor needs to be adjusted correctly or cleaned.
Dirty or damaged fuel pump - Service or replace fuel pump.
Ignition system failure - Check ignition and replace faulty components.
Gaskets are damaged - Install new gaskets.
Powerhead parts are worn out - Change defective parts.
Incorrect propeller selection - Install correct propeller.
Damaged or improper size of propeller - Replace propeller.
Engine mounted at wrong transom height - Check the outboard motor mounting height.
Incorrect trim angle - Adjust trim angle correctly.
Carburetor main jet is improperly adjusted - Adjust main jet as required.
Spark plug is defective or loose - Change or re-tighten spark plug.
Worn piston, rings, or sleeve - Change defective parts.
| Engine vibrates excessively |
Damaged or bent propeller - Replace propeller.
Propeller shaft damaged - Have propeller shaft replaced.
Weeds in the propeller - Remove and clean propeller.
Motor mounting bolt is loose - Tighten the bolt as required.
Steering pivot is faulty or loose Tighten correctly or replace.
| Starter motor is not working |
Battery power is low - Battery is drained, charge it.
Battery discharges quickly - Battery needs to be serviced or replaced.
Faulty battery terminals or disconnected cables - Connect cables correctly or replace terminals.
Starter motor is defective - Replace or repair starter.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
